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gstreamer/gst/mpegtsdemux/mpegtspacketizer.c
Edward Hervey f062b78051 mpegtspacketizer: Improve ts_to_offset code 
* Search in current pending values first. For CBR streams we can very
  easily end up having just one initial observations and then nothing
  else (since the bitrate doesn't change).
* Use one group whether we are in that group *OR* if there is only
  one group.
* If the group to use isn't closed (points are being accumulated in the
  PCROffsetCurrent), use the latest data available for calculation
* If in the unlikelyness that all of this *still* didn't produce more
  than one data point, just return the initial offset
2014-04-18 16:23:43 +02:00

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/*
* mpegtspacketizer.c -
* Copyright (C) 2007, 2008 Alessandro Decina, Zaheer Merali
*
* Authors:
* Zaheer Merali <zaheerabbas at merali dot org>
* Alessandro Decina <alessandro@nnva.org>
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Library General Public
* License as published by the Free Software Foundation; either
* version 2 of the License, or (at your option) any later version.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Library General Public License for more details.
*
* You should have received a copy of the GNU Library General Public
* License along with this library; if not, write to the
* Free Software Foundation, Inc., 51 Franklin St, Fifth Floor,
* Boston, MA 02110-1301, USA.
*/
#include <string.h>
#include <stdlib.h>
/* Skew calculation pameters */
#define MAX_TIME (2 * GST_SECOND)
/* maximal PCR time */
#define PCR_MAX_VALUE (((((guint64)1)<<33) * 300) + 298)
#define PCR_GST_MAX_VALUE (PCR_MAX_VALUE * GST_MSECOND / (PCR_MSECOND))
#define PTS_DTS_MAX_VALUE (((guint64)1) << 33)
#include "mpegtspacketizer.h"
#include "gstmpegdesc.h"
GST_DEBUG_CATEGORY_STATIC (mpegts_packetizer_debug);
#define GST_CAT_DEFAULT mpegts_packetizer_debug
static void _init_local (void);
G_DEFINE_TYPE_EXTENDED (MpegTSPacketizer2, mpegts_packetizer, G_TYPE_OBJECT, 0,
_init_local ());
#define ABSDIFF(a,b) ((a) < (b) ? (b) - (a) : (a) - (b))
static void mpegts_packetizer_dispose (GObject * object);
static void mpegts_packetizer_finalize (GObject * object);
static GstClockTime calculate_skew (MpegTSPCR * pcr, guint64 pcrtime,
GstClockTime time);
static void _close_current_group (MpegTSPCR * pcrtable);
static void record_pcr (MpegTSPacketizer2 * packetizer, MpegTSPCR * pcrtable,
guint64 pcr, guint64 offset);
#define CONTINUITY_UNSET 255
#define VERSION_NUMBER_UNSET 255
#define TABLE_ID_UNSET 0xFF
#define PACKET_SYNC_BYTE 0x47
static inline MpegTSPCR *
get_pcr_table (MpegTSPacketizer2 * packetizer, guint16 pid)
{
MpegTSPCR *res;
res = packetizer->observations[packetizer->pcrtablelut[pid]];
if (G_UNLIKELY (res == NULL)) {
/* If we don't have a PCR table for the requested PID, create one .. */
res = g_new0 (MpegTSPCR, 1);
/* Add it to the last table position */
packetizer->observations[packetizer->lastobsid] = res;
/* Update the pcrtablelut */
packetizer->pcrtablelut[pid] = packetizer->lastobsid;
/* And increment the last know slot */
packetizer->lastobsid++;
/* Finally set the default values */
res->pid = pid;
res->base_time = GST_CLOCK_TIME_NONE;
res->base_pcrtime = GST_CLOCK_TIME_NONE;
res->last_pcrtime = GST_CLOCK_TIME_NONE;
res->window_pos = 0;
res->window_filling = TRUE;
res->window_min = 0;
res->skew = 0;
res->prev_send_diff = GST_CLOCK_TIME_NONE;
res->prev_out_time = GST_CLOCK_TIME_NONE;
res->pcroffset = 0;
res->current = g_slice_new0 (PCROffsetCurrent);
}
return res;
}
static void
pcr_offset_group_free (PCROffsetGroup * group)
{
g_free (group->values);
g_slice_free (PCROffsetGroup, group);
}
static void
flush_observations (MpegTSPacketizer2 * packetizer)
{
gint i;
for (i = 0; i < packetizer->lastobsid; i++) {
g_list_free_full (packetizer->observations[i]->groups,
(GDestroyNotify) pcr_offset_group_free);
if (packetizer->observations[i]->current)
g_slice_free (PCROffsetCurrent, packetizer->observations[i]->current);
g_free (packetizer->observations[i]);
packetizer->observations[i] = NULL;
}
memset (packetizer->pcrtablelut, 0xff, 0x2000);
packetizer->lastobsid = 0;
}
static inline MpegTSPacketizerStreamSubtable *
find_subtable (GSList * subtables, guint8 table_id, guint16 subtable_extension)
{
GSList *tmp;
/* FIXME: Make this an array ! */
for (tmp = subtables; tmp; tmp = tmp->next) {
MpegTSPacketizerStreamSubtable *sub =
(MpegTSPacketizerStreamSubtable *) tmp->data;
if (sub->table_id == table_id
&& sub->subtable_extension == subtable_extension)
return sub;
}
return FALSE;
}
static gboolean
seen_section_before (MpegTSPacketizerStream * stream, guint8 table_id,
guint16 subtable_extension, guint8 version_number, guint8 section_number,
guint8 last_section_number)
{
MpegTSPacketizerStreamSubtable *subtable;
/* Check if we've seen this table_id/subtable_extension first */
subtable = find_subtable (stream->subtables, table_id, subtable_extension);
if (!subtable) {
GST_DEBUG ("Haven't seen subtable");
return FALSE;
}
/* If we have, check it has the same version_number */
if (subtable->version_number != version_number) {
GST_DEBUG ("Different version number");
return FALSE;
}
/* Did the number of sections change ? */
if (subtable->last_section_number != last_section_number) {
GST_DEBUG ("Different last_section_number");
return FALSE;
}
/* Finally return whether we saw that section or not */
return MPEGTS_BIT_IS_SET (subtable->seen_section, section_number);
}
static MpegTSPacketizerStreamSubtable *
mpegts_packetizer_stream_subtable_new (guint8 table_id,
guint16 subtable_extension, guint8 last_section_number)
{
MpegTSPacketizerStreamSubtable *subtable;
subtable = g_new0 (MpegTSPacketizerStreamSubtable, 1);
subtable->version_number = VERSION_NUMBER_UNSET;
subtable->table_id = table_id;
subtable->subtable_extension = subtable_extension;
subtable->last_section_number = last_section_number;
return subtable;
}
static MpegTSPacketizerStream *
mpegts_packetizer_stream_new (guint16 pid)
{
MpegTSPacketizerStream *stream;
stream = (MpegTSPacketizerStream *) g_new0 (MpegTSPacketizerStream, 1);
stream->continuity_counter = CONTINUITY_UNSET;
stream->subtables = NULL;
stream->table_id = TABLE_ID_UNSET;
stream->pid = pid;
return stream;
}
static void
mpegts_packetizer_clear_section (MpegTSPacketizerStream * stream)
{
stream->continuity_counter = CONTINUITY_UNSET;
stream->section_length = 0;
stream->section_offset = 0;
stream->table_id = TABLE_ID_UNSET;
if (stream->section_data)
g_free (stream->section_data);
stream->section_data = NULL;
}
static void
mpegts_packetizer_stream_subtable_free (MpegTSPacketizerStreamSubtable *
subtable)
{
g_free (subtable);
}
static void
mpegts_packetizer_stream_free (MpegTSPacketizerStream * stream)
{
mpegts_packetizer_clear_section (stream);
if (stream->section_data)
g_free (stream->section_data);
g_slist_foreach (stream->subtables,
(GFunc) mpegts_packetizer_stream_subtable_free, NULL);
g_slist_free (stream->subtables);
g_free (stream);
}
static void
mpegts_packetizer_class_init (MpegTSPacketizer2Class * klass)
{
GObjectClass *gobject_class;
gobject_class = G_OBJECT_CLASS (klass);
gobject_class->dispose = mpegts_packetizer_dispose;
gobject_class->finalize = mpegts_packetizer_finalize;
}
static void
mpegts_packetizer_init (MpegTSPacketizer2 * packetizer)
{
packetizer->adapter = gst_adapter_new ();
packetizer->offset = 0;
packetizer->empty = TRUE;
packetizer->streams = g_new0 (MpegTSPacketizerStream *, 8192);
packetizer->packet_size = 0;
packetizer->calculate_skew = FALSE;
packetizer->calculate_offset = FALSE;
packetizer->map_data = NULL;
packetizer->map_size = 0;
packetizer->map_offset = 0;
packetizer->need_sync = FALSE;
memset (packetizer->pcrtablelut, 0xff, 0x2000);
memset (packetizer->observations, 0x0, sizeof (packetizer->observations));
packetizer->lastobsid = 0;
packetizer->nb_seen_offsets = 0;
packetizer->refoffset = -1;
packetizer->last_in_time = GST_CLOCK_TIME_NONE;
}
static void
mpegts_packetizer_dispose (GObject * object)
{
MpegTSPacketizer2 *packetizer = GST_MPEGTS_PACKETIZER (object);
if (!packetizer->disposed) {
if (packetizer->packet_size)
packetizer->packet_size = 0;
if (packetizer->streams) {
int i;
for (i = 0; i < 8192; i++) {
if (packetizer->streams[i])
mpegts_packetizer_stream_free (packetizer->streams[i]);
}
g_free (packetizer->streams);
}
gst_adapter_clear (packetizer->adapter);
g_object_unref (packetizer->adapter);
packetizer->disposed = TRUE;
packetizer->offset = 0;
packetizer->empty = TRUE;
flush_observations (packetizer);
}
if (G_OBJECT_CLASS (mpegts_packetizer_parent_class)->dispose)
G_OBJECT_CLASS (mpegts_packetizer_parent_class)->dispose (object);
}
static void
mpegts_packetizer_finalize (GObject * object)
{
if (G_OBJECT_CLASS (mpegts_packetizer_parent_class)->finalize)
G_OBJECT_CLASS (mpegts_packetizer_parent_class)->finalize (object);
}
static inline guint64
mpegts_packetizer_compute_pcr (const guint8 * data)
{
guint32 pcr1;
guint16 pcr2;
guint64 pcr, pcr_ext;
pcr1 = GST_READ_UINT32_BE (data);
pcr2 = GST_READ_UINT16_BE (data + 4);
pcr = ((guint64) pcr1) << 1;
pcr |= (pcr2 & 0x8000) >> 15;
pcr_ext = (pcr2 & 0x01ff);
return pcr * 300 + pcr_ext % 300;
}
static gboolean
mpegts_packetizer_parse_adaptation_field_control (MpegTSPacketizer2 *
packetizer, MpegTSPacketizerPacket * packet)
{
guint8 length, afcflags;
guint8 *data;
length = *packet->data++;
/* an adaptation field with length 0 is valid and
* can be used to insert a single stuffing byte */
if (!length) {
packet->afc_flags = 0;
return TRUE;
}
if ((packet->scram_afc_cc & 0x30) == 0x20) {
/* no payload, adaptation field of 183 bytes */
if (length > 183) {
GST_WARNING ("PID %d afc == 0x%02x and length %d > 183",
packet->pid, packet->scram_afc_cc & 0x30, length);
return FALSE;
}
if (length != 183) {
GST_WARNING ("PID %d afc == 0x%02x and length %d != 183",
packet->pid, packet->scram_afc_cc & 0x30, length);
GST_MEMDUMP ("Unknown payload", packet->data + length,
packet->data_end - packet->data - length);
}
} else if (length > 182) {
GST_WARNING ("PID %d afc == 0x%02x and length %d > 182",
packet->pid, packet->scram_afc_cc & 0x30, length);
return FALSE;
}
if (packet->data + length > packet->data_end) {
GST_DEBUG ("PID %d afc length %d overflows the buffer current %d max %d",
packet->pid, length, (gint) (packet->data - packet->data_start),
(gint) (packet->data_end - packet->data_start));
return FALSE;
}
data = packet->data;
packet->data += length;
afcflags = packet->afc_flags = *data++;
GST_DEBUG ("flags: %s%s%s%s%s%s%s%s%s",
afcflags & 0x80 ? "discontinuity " : "",
afcflags & 0x40 ? "random_access " : "",
afcflags & 0x20 ? "elementary_stream_priority " : "",
afcflags & 0x10 ? "PCR " : "",
afcflags & 0x08 ? "OPCR " : "",
afcflags & 0x04 ? "splicing_point " : "",
afcflags & 0x02 ? "transport_private_data " : "",
afcflags & 0x01 ? "extension " : "", afcflags == 0x00 ? "<none>" : "");
/* PCR */
if (afcflags & MPEGTS_AFC_PCR_FLAG) {
MpegTSPCR *pcrtable = NULL;
packet->pcr = mpegts_packetizer_compute_pcr (data);
data += 6;
GST_DEBUG ("pcr 0x%04x %" G_GUINT64_FORMAT " (%" GST_TIME_FORMAT
") offset:%" G_GUINT64_FORMAT, packet->pid, packet->pcr,
GST_TIME_ARGS (PCRTIME_TO_GSTTIME (packet->pcr)), packet->offset);
if (packetizer->calculate_skew
&& GST_CLOCK_TIME_IS_VALID (packetizer->last_in_time)) {
pcrtable = get_pcr_table (packetizer, packet->pid);
calculate_skew (pcrtable, packet->pcr, packetizer->last_in_time);
}
if (packetizer->calculate_offset) {
if (!pcrtable)
pcrtable = get_pcr_table (packetizer, packet->pid);
record_pcr (packetizer, pcrtable, packet->pcr, packet->offset);
}
}
#ifndef GST_DISABLE_GST_DEBUG
/* OPCR */
if (afcflags & MPEGTS_AFC_OPCR_FLAG) {
/* Note: We don't use/need opcr for the time being */
guint64 opcr = mpegts_packetizer_compute_pcr (data);
data += 6;
GST_DEBUG ("opcr %" G_GUINT64_FORMAT " (%" GST_TIME_FORMAT ")",
opcr, GST_TIME_ARGS (PCRTIME_TO_GSTTIME (opcr)));
}
if (afcflags & MPEGTS_AFC_SPLICING_POINT_FLAG) {
GST_DEBUG ("splice_countdown: %u", *data++);
}
if (afcflags & MPEGTS_AFC_TRANSPORT_PRIVATE_DATA_FLAG) {
guint8 len = *data++;
GST_MEMDUMP ("private data", data, len);
data += len;
}
if (afcflags & MPEGTS_AFC_EXTENSION_FLAG) {
guint8 extlen = *data++;
guint8 flags = *data++;
GST_DEBUG ("extension size:%d flags : %s%s%s", extlen,
flags & 0x80 ? "ltw " : "",
flags & 0x40 ? "piecewise_rate " : "",
flags & 0x20 ? "seamless_splice " : "");
if (flags & 0x80) {
GST_DEBUG ("legal time window: valid_flag:%d offset:%d", *data >> 7,
GST_READ_UINT16_BE (data) & 0x7fff);
data += 2;
}
}
#endif
return TRUE;
}
static MpegTSPacketizerPacketReturn
mpegts_packetizer_parse_packet (MpegTSPacketizer2 * packetizer,
MpegTSPacketizerPacket * packet)
{
guint8 *data;
guint8 tmp;
data = packet->data_start;
data += 1;
tmp = *data;
/* transport_error_indicator 1 */
if (G_UNLIKELY (tmp & 0x80))
return PACKET_BAD;
/* payload_unit_start_indicator 1 */
packet->payload_unit_start_indicator = tmp & 0x40;
/* transport_priority 1 */
/* PID 13 */
packet->pid = GST_READ_UINT16_BE (data) & 0x1FFF;
data += 2;
packet->scram_afc_cc = tmp = *data++;
/* transport_scrambling_control 2 */
if (G_UNLIKELY (tmp & 0xc0))
return PACKET_BAD;
packet->data = data;
if (FLAGS_HAS_AFC (tmp))
if (!mpegts_packetizer_parse_adaptation_field_control (packetizer, packet))
return FALSE;
if (FLAGS_HAS_PAYLOAD (tmp))
packet->payload = packet->data;
else
packet->payload = NULL;
return PACKET_OK;
}
static GstMpegTsSection *
mpegts_packetizer_parse_section_header (MpegTSPacketizer2 * packetizer,
MpegTSPacketizerStream * stream)
{
MpegTSPacketizerStreamSubtable *subtable;
GstMpegTsSection *res;
subtable =
find_subtable (stream->subtables, stream->table_id,
stream->subtable_extension);
if (subtable) {
GST_DEBUG ("Found previous subtable_extension:0x%04x",
stream->subtable_extension);
if (G_UNLIKELY (stream->version_number != subtable->version_number)) {
/* If the version number changed, reset the subtable */
subtable->version_number = stream->version_number;
subtable->last_section_number = stream->last_section_number;
memset (subtable->seen_section, 0, 32);
}
} else {
GST_DEBUG ("Appending new subtable_extension: 0x%04x",
stream->subtable_extension);
subtable = mpegts_packetizer_stream_subtable_new (stream->table_id,
stream->subtable_extension, stream->last_section_number);
subtable->version_number = stream->version_number;
stream->subtables = g_slist_prepend (stream->subtables, subtable);
}
GST_MEMDUMP ("Full section data", stream->section_data,
stream->section_length);
/* TODO ? : Replace this by an efficient version (where we provide all
* pre-parsed header data) */
res =
gst_mpegts_section_new (stream->pid, stream->section_data,
stream->section_length);
stream->section_data = NULL;
mpegts_packetizer_clear_section (stream);
if (res) {
/* NOTE : Due to the new mpegts-si system, There is a insanely low probability
* that we might have gotten a section that was corrupted (i.e. wrong crc)
* and that we consider it as seen.
*
* The reason why we consider this as acceptable is because all the previous
* checks were already done:
* * transport layer checks (DVB)
* * 0x47 validation
* * continuity counter validation
* * subtable validation
* * section_number validation
* * section_length validation
*
* The probability of this happening vs the overhead of doing CRC checks
* on all sections (including those we would not use) is just not worth it.
* */
MPEGTS_BIT_SET (subtable->seen_section, stream->section_number);
res->offset = stream->offset;
}
return res;
}
void
mpegts_packetizer_clear (MpegTSPacketizer2 * packetizer)
{
guint i;
if (packetizer->packet_size)
packetizer->packet_size = 0;
if (packetizer->streams) {
int i;
for (i = 0; i < 8192; i++) {
if (packetizer->streams[i]) {
mpegts_packetizer_stream_free (packetizer->streams[i]);
}
}
memset (packetizer->streams, 0, 8192 * sizeof (MpegTSPacketizerStream *));
}
gst_adapter_clear (packetizer->adapter);
packetizer->offset = 0;
packetizer->empty = TRUE;
packetizer->need_sync = FALSE;
packetizer->map_data = NULL;
packetizer->map_size = 0;
packetizer->map_offset = 0;
packetizer->last_in_time = GST_CLOCK_TIME_NONE;
/* Close current PCR group */
for (i = 0; i < MAX_PCR_OBS_CHANNELS; i++) {
if (packetizer->observations[i])
_close_current_group (packetizer->observations[i]);
else
break;
}
}
void
mpegts_packetizer_flush (MpegTSPacketizer2 * packetizer, gboolean hard)
{
guint i;
GST_DEBUG ("Flushing");
if (packetizer->streams) {
for (i = 0; i < 8192; i++) {
if (packetizer->streams[i]) {
mpegts_packetizer_clear_section (packetizer->streams[i]);
}
}
}
gst_adapter_clear (packetizer->adapter);
packetizer->offset = 0;
packetizer->empty = TRUE;
packetizer->need_sync = FALSE;
packetizer->map_data = NULL;
packetizer->map_size = 0;
packetizer->map_offset = 0;
packetizer->last_in_time = GST_CLOCK_TIME_NONE;
/* Close current PCR group */
for (i = 0; i < MAX_PCR_OBS_CHANNELS; i++) {
if (packetizer->observations[i])
_close_current_group (packetizer->observations[i]);
else
break;
}
if (hard) {
/* For pull mode seeks in tsdemux the observation must be preserved */
flush_observations (packetizer);
}
}
void
mpegts_packetizer_remove_stream (MpegTSPacketizer2 * packetizer, gint16 pid)
{
MpegTSPacketizerStream *stream = packetizer->streams[pid];
if (stream) {
GST_INFO ("Removing stream for PID %d", pid);
mpegts_packetizer_stream_free (stream);
packetizer->streams[pid] = NULL;
}
}
MpegTSPacketizer2 *
mpegts_packetizer_new (void)
{
MpegTSPacketizer2 *packetizer;
packetizer =
GST_MPEGTS_PACKETIZER (g_object_new (GST_TYPE_MPEGTS_PACKETIZER, NULL));
return packetizer;
}
void
mpegts_packetizer_push (MpegTSPacketizer2 * packetizer, GstBuffer * buffer)
{
if (G_UNLIKELY (packetizer->empty)) {
packetizer->empty = FALSE;
packetizer->offset = GST_BUFFER_OFFSET (buffer);
}
GST_DEBUG ("Pushing %" G_GSIZE_FORMAT " byte from offset %"
G_GUINT64_FORMAT, gst_buffer_get_size (buffer),
GST_BUFFER_OFFSET (buffer));
gst_adapter_push (packetizer->adapter, buffer);
/* If buffer timestamp is valid, store it */
if (GST_CLOCK_TIME_IS_VALID (GST_BUFFER_TIMESTAMP (buffer)))
packetizer->last_in_time = GST_BUFFER_TIMESTAMP (buffer);
}
static void
mpegts_packetizer_flush_bytes (MpegTSPacketizer2 * packetizer, gsize size)
{
if (size > 0) {
GST_LOG ("flushing %" G_GSIZE_FORMAT " bytes from adapter", size);
gst_adapter_flush (packetizer->adapter, size);
}
packetizer->map_data = NULL;
packetizer->map_size = 0;
packetizer->map_offset = 0;
}
static gboolean
mpegts_packetizer_map (MpegTSPacketizer2 * packetizer, gsize size)
{
gsize available;
if (packetizer->map_size - packetizer->map_offset >= size)
return TRUE;
mpegts_packetizer_flush_bytes (packetizer, packetizer->map_offset);
available = gst_adapter_available (packetizer->adapter);
if (available < size)
return FALSE;
packetizer->map_data =
(guint8 *) gst_adapter_map (packetizer->adapter, available);
if (!packetizer->map_data)
return FALSE;
packetizer->map_size = available;
packetizer->map_offset = 0;
GST_LOG ("mapped %" G_GSIZE_FORMAT " bytes from adapter", available);
return TRUE;
}
static gboolean
mpegts_try_discover_packet_size (MpegTSPacketizer2 * packetizer)
{
guint8 *data;
gsize size, i, j;
static const guint psizes[] = {
MPEGTS_NORMAL_PACKETSIZE,
MPEGTS_M2TS_PACKETSIZE,
MPEGTS_DVB_ASI_PACKETSIZE,
MPEGTS_ATSC_PACKETSIZE
};
if (!mpegts_packetizer_map (packetizer, 4 * MPEGTS_MAX_PACKETSIZE))
return FALSE;
size = packetizer->map_size - packetizer->map_offset;
data = packetizer->map_data + packetizer->map_offset;
for (i = 0; i + 3 * MPEGTS_MAX_PACKETSIZE < size; i++) {
/* find a sync byte */
if (data[i] != PACKET_SYNC_BYTE)
continue;
/* check for 4 consecutive sync bytes with each possible packet size */
for (j = 0; j < G_N_ELEMENTS (psizes); j++) {
guint packet_size = psizes[j];
if (data[i + packet_size] == PACKET_SYNC_BYTE &&
data[i + 2 * packet_size] == PACKET_SYNC_BYTE &&
data[i + 3 * packet_size] == PACKET_SYNC_BYTE) {
packetizer->packet_size = packet_size;
goto out;
}
}
}
out:
packetizer->map_offset += i;
if (packetizer->packet_size == 0) {
GST_DEBUG ("Could not determine packet size in %" G_GSIZE_FORMAT
" bytes buffer, flush %" G_GSIZE_FORMAT " bytes", size, i);
mpegts_packetizer_flush_bytes (packetizer, packetizer->map_offset);
return FALSE;
}
GST_INFO ("have packetsize detected: %u bytes", packetizer->packet_size);
if (packetizer->packet_size == MPEGTS_M2TS_PACKETSIZE &&
packetizer->map_offset >= 4)
packetizer->map_offset -= 4;
return TRUE;
}
static gboolean
mpegts_packetizer_sync (MpegTSPacketizer2 * packetizer)
{
gboolean found = FALSE;
guint8 *data;
guint packet_size;
gsize size, sync_offset, i;
packet_size = packetizer->packet_size;
if (!mpegts_packetizer_map (packetizer, 3 * packet_size))
return FALSE;
size = packetizer->map_size - packetizer->map_offset;
data = packetizer->map_data + packetizer->map_offset;
if (packet_size == MPEGTS_M2TS_PACKETSIZE)
sync_offset = 4;
else
sync_offset = 0;
for (i = sync_offset; i + 2 * packet_size < size; i++) {
if (data[i] == PACKET_SYNC_BYTE &&
data[i + packet_size] == PACKET_SYNC_BYTE &&
data[i + 2 * packet_size] == PACKET_SYNC_BYTE) {
found = TRUE;
break;
}
}
packetizer->map_offset += i - sync_offset;
if (!found)
mpegts_packetizer_flush_bytes (packetizer, packetizer->map_offset);
return found;
}
MpegTSPacketizerPacketReturn
mpegts_packetizer_next_packet (MpegTSPacketizer2 * packetizer,
MpegTSPacketizerPacket * packet)
{
guint8 *packet_data;
guint packet_size;
gsize sync_offset;
packet_size = packetizer->packet_size;
if (G_UNLIKELY (!packet_size)) {
if (!mpegts_try_discover_packet_size (packetizer))
return PACKET_NEED_MORE;
packet_size = packetizer->packet_size;
}
/* M2TS packets don't start with the sync byte, all other variants do */
if (packet_size == MPEGTS_M2TS_PACKETSIZE)
sync_offset = 4;
else
sync_offset = 0;
while (1) {
if (packetizer->need_sync) {
if (!mpegts_packetizer_sync (packetizer))
return PACKET_NEED_MORE;
packetizer->need_sync = FALSE;
}
if (!mpegts_packetizer_map (packetizer, packet_size))
return PACKET_NEED_MORE;
packet_data = &packetizer->map_data[packetizer->map_offset + sync_offset];
/* Check sync byte */
if (G_UNLIKELY (*packet_data != PACKET_SYNC_BYTE)) {
GST_DEBUG ("lost sync");
packetizer->need_sync = TRUE;
} else {
/* ALL mpeg-ts variants contain 188 bytes of data. Those with bigger
* packet sizes contain either extra data (timesync, FEC, ..) either
* before or after the data */
packet->data_start = packet_data;
packet->data_end = packet->data_start + 188;
packet->offset = packetizer->offset;
GST_LOG ("offset %" G_GUINT64_FORMAT, packet->offset);
packetizer->offset += packet_size;
GST_MEMDUMP ("data_start", packet->data_start, 16);
return mpegts_packetizer_parse_packet (packetizer, packet);
}
}
}
MpegTSPacketizerPacketReturn
mpegts_packetizer_process_next_packet (MpegTSPacketizer2 * packetizer)
{
MpegTSPacketizerPacket packet;
MpegTSPacketizerPacketReturn ret;
ret = mpegts_packetizer_next_packet (packetizer, &packet);
if (ret != PACKET_NEED_MORE)
mpegts_packetizer_clear_packet (packetizer, &packet);
return ret;
}
void
mpegts_packetizer_clear_packet (MpegTSPacketizer2 * packetizer,
MpegTSPacketizerPacket * packet)
{
guint8 packet_size = packetizer->packet_size;
if (packetizer->map_data) {
packetizer->map_offset += packet_size;
if (packetizer->map_size - packetizer->map_offset < packet_size)
mpegts_packetizer_flush_bytes (packetizer, packetizer->map_offset);
}
}
gboolean
mpegts_packetizer_has_packets (MpegTSPacketizer2 * packetizer)
{
if (G_UNLIKELY (!packetizer->packet_size)) {
if (!mpegts_try_discover_packet_size (packetizer))
return FALSE;
}
return gst_adapter_available (packetizer->adapter) >= packetizer->packet_size;
}
/*
* Ideally it should just return a section if:
* * The section is complete
* * The section is valid (sanity checks for length for example)
* * The section applies now (current_next_indicator)
* * The section is an update or was never seen
*
* The section should be a new GstMpegTsSection:
* * properly initialized
* * With pid, table_id AND section_type set (move logic from mpegtsbase)
* * With data copied into it (yes, minor overhead)
*
* In all other cases it should just return NULL
*
* If more than one section is available, the 'remaining' field will
* be set to the beginning of a valid GList containing other sections.
* */
GstMpegTsSection *
mpegts_packetizer_push_section (MpegTSPacketizer2 * packetizer,
MpegTSPacketizerPacket * packet, GList ** remaining)
{
GstMpegTsSection *section;
GstMpegTsSection *res = NULL;
MpegTSPacketizerStream *stream;
gboolean long_packet;
guint8 pointer = 0, table_id;
guint16 subtable_extension = 0;
gsize to_read;
guint section_length;
/* data points to the current read location
* data_start points to the beginning of the data to accumulate */
guint8 *data, *data_start;
guint8 packet_cc;
GList *others = NULL;
guint8 version_number, section_number, last_section_number;
data = packet->data;
packet_cc = FLAGS_CONTINUITY_COUNTER (packet->scram_afc_cc);
/* Get our filter */
stream = packetizer->streams[packet->pid];
if (G_UNLIKELY (stream == NULL)) {
if (!packet->payload_unit_start_indicator) {
/* Early exit (we need to start with a section start) */
GST_DEBUG ("PID 0x%04x waiting for section start", packet->pid);
goto out;
}
stream = mpegts_packetizer_stream_new (packet->pid);
packetizer->streams[packet->pid] = stream;
}
GST_MEMDUMP ("Full packet data", packet->data,
packet->data_end - packet->data);
/* This function is split into several parts:
*
* Pre checks (packet-wide). Determines where we go next
* accumulate_data: store data and check if section is complete
* section_start: handle beginning of a section, if needed loop back to
* accumulate_data
*
* The trigger that makes the loop stop and return is if:
* 1) We do not have enough data for the current packet
* 2) There is remaining data after a packet which is only made
* of stuffing bytes (0xff).
*
* Pre-loop checks, related to the whole incoming packet:
*
* If there is a CC-discont:
* If it is a PUSI, skip the pointer and handle section_start
* If not a PUSI, reset and return nothing
* If there is not a CC-discont:
* If it is a PUSI
* If pointer, accumulate that data and check for complete section
* (loop)
* If it is not a PUSI
* Accumulate the expected data and check for complete section
* (loop)
*
**/
if (packet->payload_unit_start_indicator) {
pointer = *data++;
/* If the pointer is zero, we're guaranteed to be able to handle it */
if (pointer == 0) {
GST_LOG
("PID 0x%04x PUSI and pointer == 0, skipping straight to section_start parsing",
packet->pid);
goto section_start;
}
}
if (stream->continuity_counter == CONTINUITY_UNSET ||
(stream->continuity_counter + 1) % 16 != packet_cc) {
if (stream->continuity_counter != CONTINUITY_UNSET)
GST_WARNING ("PID 0x%04x section discontinuity (%d vs %d)", packet->pid,
stream->continuity_counter, packet_cc);
mpegts_packetizer_clear_section (stream);
/* If not a PUSI, not much we can do */
if (!packet->payload_unit_start_indicator) {
GST_LOG ("PID 0x%04x continuity discont/unset and not PUSI, bailing out",
packet->pid);
goto out;
}
/* If PUSI, skip pointer data and carry on to section start */
data += pointer;
pointer = 0;
GST_LOG ("discont, but PUSI, skipped %d bytes and doing section start",
pointer);
goto section_start;
}
GST_LOG ("Accumulating data from beginning of packet");
data_start = data;
accumulate_data:
/* If not the beginning of a new section, accumulate what we have */
stream->continuity_counter = packet_cc;
to_read = MIN (stream->section_length - stream->section_offset,
packet->data_end - data_start);
memcpy (stream->section_data + stream->section_offset, data_start, to_read);
stream->section_offset += to_read;
/* Point data to after the data we accumulated */
data = data_start + to_read;
GST_DEBUG ("Appending data (need %d, have %d)", stream->section_length,
stream->section_offset);
/* Check if we have enough */
if (stream->section_offset < stream->section_length) {
GST_DEBUG ("PID 0x%04x, section not complete (Got %d, need %d)",
stream->pid, stream->section_offset, stream->section_length);
goto out;
}
/* Small sanity check. We should have collected *exactly* the right amount */
if (G_UNLIKELY (stream->section_offset != stream->section_length))
GST_WARNING ("PID 0x%04x Accumulated too much data (%d vs %d) !",
stream->pid, stream->section_offset, stream->section_length);
GST_DEBUG ("PID 0x%04x Section complete", stream->pid);
if ((section = mpegts_packetizer_parse_section_header (packetizer, stream))) {
if (res)
others = g_list_append (others, section);
else
res = section;
}
/* FIXME : We need at least 8 bytes with current algorithm :(
* We might end up losing sections that start across two packets (srsl...) */
if (data > packet->data_end - 8 || *data == 0xff) {
/* flush stuffing bytes and leave */
mpegts_packetizer_clear_section (stream);
goto out;
}
/* We have more data to process ... */
GST_DEBUG ("PID 0x%04x, More section present in packet (remaining bytes:%"
G_GSIZE_FORMAT ")", stream->pid, packet->data_end - data);
section_start:
GST_MEMDUMP ("section_start", data, packet->data_end - data);
data_start = data;
/* Beginning of a new section */
/*
* section_syntax_indicator means that the header is of the following format:
* * table_id (8bit)
* * section_syntax_indicator (1bit) == 0
* * reserved/private fields (3bit)
* * section_length (12bit)
* * data (of size section_length)
* * NO CRC !
*/
long_packet = data[1] & 0x80;
/* Fast path for short packets */
if (!long_packet) {
/* We can create the section now (function will check for size) */
GST_DEBUG ("Short packet");
section_length = (GST_READ_UINT16_BE (data + 1) & 0xfff) + 3;
/* Only do fast-path if we have enough byte */
if (section_length < packet->data_end - data) {
if ((section =
gst_mpegts_section_new (packet->pid, g_memdup (data,
section_length), section_length))) {
GST_DEBUG ("PID 0x%04x Short section complete !", packet->pid);
section->offset = packet->offset;
if (res)
others = g_list_append (others, section);
else
res = section;
}
/* Advance reader and potentially read another section */
data += section_length;
if (data < packet->data_end && *data != 0xff)
goto section_start;
/* If not, exit */
goto out;
}
/* We don't have enough bytes to do short section shortcut */
}
/* Beginning of a new section, do as much pre-parsing as possible */
/* table_id : 8 bit */
table_id = *data++;
/* section_syntax_indicator : 1 bit
* other_fields (reserved) : 3 bit
* section_length : 12 bit */
section_length = (GST_READ_UINT16_BE (data) & 0x0FFF) + 3;
data += 2;
if (long_packet) {
/* subtable_extension (always present, we are in a long section) */
/* subtable extension : 16 bit */
subtable_extension = GST_READ_UINT16_BE (data);
data += 2;
/* reserved : 2 bit
* version_number : 5 bit
* current_next_indicator : 1 bit */
/* Bail out now if current_next_indicator == 0 */
if (G_UNLIKELY (!(*data & 0x01))) {
GST_DEBUG
("PID 0x%04x table_id 0x%02x section does not apply (current_next_indicator == 0)",
packet->pid, table_id);
goto out;
}
version_number = *data++ >> 1 & 0x1f;
/* section_number : 8 bit */
section_number = *data++;
/* last_section_number : 8 bit */
last_section_number = *data++;
} else {
subtable_extension = 0;
version_number = 0;
section_number = 0;
last_section_number = 0;
}
GST_DEBUG
("PID 0x%04x length:%d table_id:0x%02x subtable_extension:0x%04x version_number:%d section_number:%d(last:%d)",
packet->pid, section_length, table_id, subtable_extension, version_number,
section_number, last_section_number);
to_read = MIN (section_length, packet->data_end - data_start);
/* Check as early as possible whether we already saw this section
* i.e. that we saw a subtable with:
* * same subtable_extension (might be zero)
* * same version_number
* * same last_section_number
* * same section_number was seen
*/
if (seen_section_before (stream, table_id, subtable_extension,
version_number, section_number, last_section_number)) {
GST_DEBUG
("PID 0x%04x Already processed table_id:0x%02x subtable_extension:0x%04x, version_number:%d, section_number:%d",
packet->pid, table_id, subtable_extension, version_number,
section_number);
/* skip data and see if we have more sections after */
data = data_start + to_read;
if (data == packet->data_end || *data == 0xff)
goto out;
goto section_start;
}
if (G_UNLIKELY (section_number > last_section_number)) {
GST_WARNING
("PID 0x%04x corrupted packet (section_number:%d > last_section_number:%d)",
packet->pid, section_number, last_section_number);
goto out;
}
/* Copy over already parsed values */
stream->table_id = table_id;
stream->section_length = section_length;
stream->version_number = version_number;
stream->subtable_extension = subtable_extension;
stream->section_number = section_number;
stream->last_section_number = last_section_number;
stream->offset = packet->offset;
/* Create enough room to store chunks of sections */
stream->section_data = g_malloc (stream->section_length);
stream->section_offset = 0;
/* Finally, accumulate and check if we parsed enough */
goto accumulate_data;
out:
packet->data = data;
*remaining = others;
GST_DEBUG ("result: %p", res);
return res;
}
static void
_init_local (void)
{
GST_DEBUG_CATEGORY_INIT (mpegts_packetizer_debug, "mpegtspacketizer", 0,
"MPEG transport stream parser");
}
static void
mpegts_packetizer_resync (MpegTSPCR * pcr, GstClockTime time,
GstClockTime gstpcrtime, gboolean reset_skew)
{
pcr->base_time = time;
pcr->base_pcrtime = gstpcrtime;
pcr->prev_out_time = GST_CLOCK_TIME_NONE;
pcr->prev_send_diff = GST_CLOCK_TIME_NONE;
if (reset_skew) {
pcr->window_filling = TRUE;
pcr->window_pos = 0;
pcr->window_min = 0;
pcr->window_size = 0;
pcr->skew = 0;
}
}
/* Code mostly copied from -good/gst/rtpmanager/rtpjitterbuffer.c */
/* For the clock skew we use a windowed low point averaging algorithm as can be
* found in Fober, Orlarey and Letz, 2005, "Real Time Clock Skew Estimation
* over Network Delays":
* http://www.grame.fr/Ressources/pub/TR-050601.pdf
* http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.102.1546
*
* The idea is that the jitter is composed of:
*
* J = N + n
*
* N : a constant network delay.
* n : random added noise. The noise is concentrated around 0
*
* In the receiver we can track the elapsed time at the sender with:
*
* send_diff(i) = (Tsi - Ts0);
*
* Tsi : The time at the sender at packet i
* Ts0 : The time at the sender at the first packet
*
* This is the difference between the RTP timestamp in the first received packet
* and the current packet.
*
* At the receiver we have to deal with the jitter introduced by the network.
*
* recv_diff(i) = (Tri - Tr0)
*
* Tri : The time at the receiver at packet i
* Tr0 : The time at the receiver at the first packet
*
* Both of these values contain a jitter Ji, a jitter for packet i, so we can
* write:
*
* recv_diff(i) = (Cri + D + ni) - (Cr0 + D + n0))
*
* Cri : The time of the clock at the receiver for packet i
* D + ni : The jitter when receiving packet i
*
* We see that the network delay is irrelevant here as we can elliminate D:
*
* recv_diff(i) = (Cri + ni) - (Cr0 + n0))
*
* The drift is now expressed as:
*
* Drift(i) = recv_diff(i) - send_diff(i);
*
* We now keep the W latest values of Drift and find the minimum (this is the
* one with the lowest network jitter and thus the one which is least affected
* by it). We average this lowest value to smooth out the resulting network skew.
*
* Both the window and the weighting used for averaging influence the accuracy
* of the drift estimation. Finding the correct parameters turns out to be a
* compromise between accuracy and inertia.
*
* We use a 2 second window or up to 512 data points, which is statistically big
* enough to catch spikes (FIXME, detect spikes).
* We also use a rather large weighting factor (125) to smoothly adapt. During
* startup, when filling the window, we use a parabolic weighting factor, the
* more the window is filled, the faster we move to the detected possible skew.
*
* Returns: @time adjusted with the clock skew.
*/
static GstClockTime
calculate_skew (MpegTSPCR * pcr, guint64 pcrtime, GstClockTime time)
{
guint64 send_diff, recv_diff;
gint64 delta;
gint64 old;
gint pos, i;
GstClockTime gstpcrtime, out_time;
#ifndef GST_DISABLE_GST_DEBUG
guint64 slope;
#endif
gstpcrtime = PCRTIME_TO_GSTTIME (pcrtime) + pcr->pcroffset;
/* first time, lock on to time and gstpcrtime */
if (G_UNLIKELY (!GST_CLOCK_TIME_IS_VALID (pcr->base_time))) {
pcr->base_time = time;
pcr->prev_out_time = GST_CLOCK_TIME_NONE;
GST_DEBUG ("Taking new base time %" GST_TIME_FORMAT, GST_TIME_ARGS (time));
}
if (G_UNLIKELY (!GST_CLOCK_TIME_IS_VALID (pcr->base_pcrtime))) {
pcr->base_pcrtime = gstpcrtime;
pcr->prev_send_diff = -1;
GST_DEBUG ("Taking new base pcrtime %" GST_TIME_FORMAT,
GST_TIME_ARGS (gstpcrtime));
}
/* Handle PCR wraparound and resets */
if (GST_CLOCK_TIME_IS_VALID (pcr->last_pcrtime) &&
gstpcrtime < pcr->last_pcrtime) {
if (pcr->last_pcrtime - gstpcrtime > PCR_GST_MAX_VALUE / 2) {
/* PCR wraparound */
GST_DEBUG ("PCR wrap");
pcr->pcroffset += PCR_GST_MAX_VALUE;
gstpcrtime = PCRTIME_TO_GSTTIME (pcrtime) + pcr->pcroffset;
send_diff = gstpcrtime - pcr->base_pcrtime;
} else if (GST_CLOCK_TIME_IS_VALID (time)
&& pcr->last_pcrtime - gstpcrtime > 15 * GST_SECOND) {
/* Assume a reset */
GST_DEBUG ("PCR reset");
/* Calculate PCR we would have expected for the given input time,
* essentially applying the reverse correction process
*
* We want to find the PCR offset to apply
* pcroffset = (corrected) gstpcrtime - (received) gstpcrtime
*
* send_diff = (corrected) gstpcrtime - pcr->base_pcrtime
* recv_diff = time - pcr->base_time
* out_time = pcr->base_time + send_diff
*
* We are assuming that send_diff == recv_diff
* (corrected) gstpcrtime - pcr->base_pcrtime = time - pcr->base_time
* Giving us:
* (corrected) gstpcrtime = time - pcr->base_time + pcr->base_pcrtime
*
* And therefore:
* pcroffset = time - pcr->base_time + pcr->base_pcrtime - (received) gstpcrtime
**/
pcr->pcroffset += time - pcr->base_time + pcr->base_pcrtime - gstpcrtime;
gstpcrtime = PCRTIME_TO_GSTTIME (pcrtime) + pcr->pcroffset;
send_diff = gstpcrtime - pcr->base_pcrtime;
GST_DEBUG ("Introduced offset is now %" GST_TIME_FORMAT
" corrected pcr time %" GST_TIME_FORMAT,
GST_TIME_ARGS (pcr->pcroffset), GST_TIME_ARGS (gstpcrtime));
} else {
GST_WARNING ("backward timestamps at server but no timestamps");
send_diff = 0;
/* at least try to get a new timestamp.. */
pcr->base_time = GST_CLOCK_TIME_NONE;
}
} else
send_diff = gstpcrtime - pcr->base_pcrtime;
GST_DEBUG ("gstpcr %" GST_TIME_FORMAT ", buftime %" GST_TIME_FORMAT
", base %" GST_TIME_FORMAT ", send_diff %" GST_TIME_FORMAT,
GST_TIME_ARGS (gstpcrtime), GST_TIME_ARGS (time),
GST_TIME_ARGS (pcr->base_pcrtime), GST_TIME_ARGS (send_diff));
/* keep track of the last extended pcrtime */
pcr->last_pcrtime = gstpcrtime;
/* we don't have an arrival timestamp so we can't do skew detection. we
* should still apply a timestamp based on RTP timestamp and base_time */
if (!GST_CLOCK_TIME_IS_VALID (time)
|| !GST_CLOCK_TIME_IS_VALID (pcr->base_time))
goto no_skew;
/* elapsed time at receiver, includes the jitter */
recv_diff = time - pcr->base_time;
/* Ignore packets received at 100% the same time (i.e. from the same input buffer) */
if (G_UNLIKELY (time == pcr->prev_in_time
&& GST_CLOCK_TIME_IS_VALID (pcr->prev_in_time)))
goto no_skew;
/* measure the diff */
delta = ((gint64) recv_diff) - ((gint64) send_diff);
#ifndef GST_DISABLE_GST_DEBUG
/* measure the slope, this gives a rought estimate between the sender speed
* and the receiver speed. This should be approximately 8, higher values
* indicate a burst (especially when the connection starts) */
slope = recv_diff > 0 ? (send_diff * 8) / recv_diff : 8;
#endif
GST_DEBUG ("time %" GST_TIME_FORMAT ", base %" GST_TIME_FORMAT
", recv_diff %" GST_TIME_FORMAT ", slope %" G_GUINT64_FORMAT,
GST_TIME_ARGS (time), GST_TIME_ARGS (pcr->base_time),
GST_TIME_ARGS (recv_diff), slope);
/* if the difference between the sender timeline and the receiver timeline
* changed too quickly we have to resync because the server likely restarted
* its timestamps. */
if (ABS (delta - pcr->skew) > GST_SECOND) {
GST_WARNING ("delta - skew: %" GST_TIME_FORMAT " too big, reset skew",
GST_TIME_ARGS (delta - pcr->skew));
mpegts_packetizer_resync (pcr, time, gstpcrtime, TRUE);
send_diff = 0;
delta = 0;
}
pos = pcr->window_pos;
if (G_UNLIKELY (pcr->window_filling)) {
/* we are filling the window */
GST_DEBUG ("filling %d, delta %" G_GINT64_FORMAT, pos, delta);
pcr->window[pos++] = delta;
/* calc the min delta we observed */
if (G_UNLIKELY (pos == 1 || delta < pcr->window_min))
pcr->window_min = delta;
if (G_UNLIKELY (send_diff >= MAX_TIME || pos >= MAX_WINDOW)) {
pcr->window_size = pos;
/* window filled */
GST_DEBUG ("min %" G_GINT64_FORMAT, pcr->window_min);
/* the skew is now the min */
pcr->skew = pcr->window_min;
pcr->window_filling = FALSE;
} else {
gint perc_time, perc_window, perc;
/* figure out how much we filled the window, this depends on the amount of
* time we have or the max number of points we keep. */
perc_time = send_diff * 100 / MAX_TIME;
perc_window = pos * 100 / MAX_WINDOW;
perc = MAX (perc_time, perc_window);
/* make a parabolic function, the closer we get to the MAX, the more value
* we give to the scaling factor of the new value */
perc = perc * perc;
/* quickly go to the min value when we are filling up, slowly when we are
* just starting because we're not sure it's a good value yet. */
pcr->skew =
(perc * pcr->window_min + ((10000 - perc) * pcr->skew)) / 10000;
pcr->window_size = pos + 1;
}
} else {
/* pick old value and store new value. We keep the previous value in order
* to quickly check if the min of the window changed */
old = pcr->window[pos];
pcr->window[pos++] = delta;
if (G_UNLIKELY (delta <= pcr->window_min)) {
/* if the new value we inserted is smaller or equal to the current min,
* it becomes the new min */
pcr->window_min = delta;
} else if (G_UNLIKELY (old == pcr->window_min)) {
gint64 min = G_MAXINT64;
/* if we removed the old min, we have to find a new min */
for (i = 0; i < pcr->window_size; i++) {
/* we found another value equal to the old min, we can stop searching now */
if (pcr->window[i] == old) {
min = old;
break;
}
if (pcr->window[i] < min)
min = pcr->window[i];
}
pcr->window_min = min;
}
/* average the min values */
pcr->skew = (pcr->window_min + (124 * pcr->skew)) / 125;
GST_DEBUG ("delta %" G_GINT64_FORMAT ", new min: %" G_GINT64_FORMAT,
delta, pcr->window_min);
}
/* wrap around in the window */
if (G_UNLIKELY (pos >= pcr->window_size))
pos = 0;
pcr->window_pos = pos;
no_skew:
/* the output time is defined as the base timestamp plus the PCR time
* adjusted for the clock skew .*/
if (pcr->base_time != -1) {
out_time = pcr->base_time + send_diff;
/* skew can be negative and we don't want to make invalid timestamps */
if (pcr->skew < 0 && out_time < -pcr->skew) {
out_time = 0;
} else {
out_time += pcr->skew;
}
/* check if timestamps are not going backwards, we can only check this if we
* have a previous out time and a previous send_diff */
if (G_LIKELY (pcr->prev_out_time != -1 && pcr->prev_send_diff != -1)) {
/* now check for backwards timestamps */
if (G_UNLIKELY (
/* if the server timestamps went up and the out_time backwards */
(send_diff > pcr->prev_send_diff
&& out_time < pcr->prev_out_time) ||
/* if the server timestamps went backwards and the out_time forwards */
(send_diff < pcr->prev_send_diff
&& out_time > pcr->prev_out_time) ||
/* if the server timestamps did not change */
send_diff == pcr->prev_send_diff)) {
GST_DEBUG ("backwards timestamps, using previous time");
out_time = GSTTIME_TO_MPEGTIME (out_time);
}
}
} else {
/* We simply use the pcrtime without applying any skew compensation */
out_time = time;
}
pcr->prev_out_time = out_time;
pcr->prev_in_time = time;
pcr->prev_send_diff = send_diff;
GST_DEBUG ("skew %" G_GINT64_FORMAT ", out %" GST_TIME_FORMAT,
pcr->skew, GST_TIME_ARGS (out_time));
return out_time;
}
static void
_reevaluate_group_pcr_offset (MpegTSPCR * pcrtable, PCROffsetGroup * group)
{
PCROffsetGroup *prev = NULL;
#ifndef GST_DISABLE_GST_DEBUG
PCROffsetGroup *first = pcrtable->groups->data;
#endif
PCROffsetCurrent *current = pcrtable->current;
GList *tmp;
/* Go over all ESTIMATED groups until the target group */
for (tmp = pcrtable->groups; tmp; tmp = tmp->next) {
PCROffsetGroup *cur = (PCROffsetGroup *) tmp->data;
/* Skip groups that don't need re-evaluation */
if (!(cur->flags & PCR_GROUP_FLAG_ESTIMATED)) {
GST_DEBUG ("Skipping group %p pcr_offset (currently %" GST_TIME_FORMAT
")", cur, GST_TIME_ARGS (PCRTIME_TO_GSTTIME (cur->pcr_offset)));
prev = cur;
continue;
}
/* This should not happen ! The first group is *always* correct (zero) */
if (G_UNLIKELY (prev == NULL)) {
GST_ERROR ("First PCR Group was not estimated (bug). Setting to zero");
cur->pcr_offset = 0;
cur->flags &= ~PCR_GROUP_FLAG_ESTIMATED;
return;
}
/* Finally do the estimation of this group's PCR offset based on the
* previous group information */
GST_DEBUG ("Re-evaluating group %p pcr_offset (currently %" GST_TIME_FORMAT
")", group, GST_TIME_ARGS (PCRTIME_TO_GSTTIME (cur->pcr_offset)));
GST_DEBUG ("cur->first_pcr:%" GST_TIME_FORMAT " prev->first_pcr:%"
GST_TIME_FORMAT, GST_TIME_ARGS (PCRTIME_TO_GSTTIME (cur->first_pcr)),
GST_TIME_ARGS (PCRTIME_TO_GSTTIME (prev->first_pcr)));
if (G_UNLIKELY (cur->first_pcr < prev->first_pcr)) {
guint64 prevbr, lastbr;
guint64 prevpcr;
guint64 prevoffset, lastoffset;
/* Take the previous group pcr_offset and figure out how much to add
* to it for the current group */
/* Right now we do a dumb bitrate estimation
* estimate bitrate (prev - first) : bitrate from the start
* estimate bitrate (prev) : bitrate of previous group
* estimate bitrate (last - first) : bitrate from previous group
*
* We will use raw (non-corrected/non-absolute) PCR values in a first time
* to detect wraparound/resets/gaps...
*
* We will use the corrected/asolute PCR values to calculate
* bitrate and estimate the target group pcr_offset.
* */
/* If the current window estimator is over the previous group, used those
* values as the latest (since they are more recent) */
if (current->group == prev && current->pending[current->last].offset) {
prevoffset =
current->pending[current->last].offset + prev->first_offset;
prevpcr = current->pending[current->last].pcr + prev->first_pcr;
/* prevbr: bitrate(prev) */
prevbr =
gst_util_uint64_scale (PCR_SECOND,
current->pending[current->last].offset,
current->pending[current->last].pcr);
GST_DEBUG ("Previous group bitrate (%u / %" GST_TIME_FORMAT ") : %"
G_GUINT64_FORMAT, current->pending[current->last].offset,
GST_TIME_ARGS (PCRTIME_TO_GSTTIME (current->pending[current->
last].pcr)), prevbr);
} else if (prev->values[prev->last_value].offset) {
prevoffset = prev->values[prev->last_value].offset + prev->first_offset;
prevpcr = prev->values[prev->last_value].pcr + prev->first_pcr;
/* prevbr: bitrate(prev) (FIXME : Cache) */
prevbr =
gst_util_uint64_scale (PCR_SECOND,
prev->values[prev->last_value].offset,
prev->values[prev->last_value].pcr);
GST_DEBUG ("Previous group bitrate (%u / %" GST_TIME_FORMAT ") : %"
G_GUINT64_FORMAT, prev->values[prev->last_value].offset,
GST_TIME_ARGS (PCRTIME_TO_GSTTIME (prev->values[prev->
last_value].pcr)), prevbr);
} else {
GST_DEBUG ("Using overall bitrate");
prevoffset = prev->values[prev->last_value].offset + prev->first_offset;
prevpcr = prev->values[prev->last_value].pcr + prev->first_pcr;
prevbr = gst_util_uint64_scale (PCR_SECOND,
prev->first_offset, prev->pcr_offset);
}
lastoffset = cur->values[cur->last_value].offset + cur->first_offset;
GST_DEBUG ("Offset first:%" G_GUINT64_FORMAT " prev:%" G_GUINT64_FORMAT
" cur:%" G_GUINT64_FORMAT, first->first_offset, prevoffset,
lastoffset);
GST_DEBUG ("PCR first:%" GST_TIME_FORMAT " prev:%" GST_TIME_FORMAT
" cur:%" GST_TIME_FORMAT,
GST_TIME_ARGS (PCRTIME_TO_GSTTIME (first->first_pcr)),
GST_TIME_ARGS (PCRTIME_TO_GSTTIME (prevpcr)),
GST_TIME_ARGS (PCRTIME_TO_GSTTIME (cur->values[cur->last_value].pcr +
cur->first_pcr)));
if (prevpcr - cur->first_pcr > (PCR_MAX_VALUE * 9 / 10)) {
gfloat diffprev;
guint64 guess_offset;
/* Let's assume there is a PCR wraparound between the previous and current
* group.
* [ prev ]... PCR_MAX | 0 ...[ current ]
* The estimated pcr_offset would therefore be:
* current.first + (PCR_MAX_VALUE - prev.first)
*
* 1) Check if bitrate(prev) would be consistent with bitrate (cur - prev)
*/
guess_offset = PCR_MAX_VALUE - prev->first_pcr + cur->first_pcr;
lastbr = gst_util_uint64_scale (PCR_SECOND, lastoffset - prevoffset,
guess_offset + cur->values[cur->last_value].pcr - (prevpcr -
prev->first_pcr));
GST_DEBUG ("Wraparound prev-cur (guess_offset:%" GST_TIME_FORMAT
") bitrate:%" G_GUINT64_FORMAT,
GST_TIME_ARGS (PCRTIME_TO_GSTTIME (guess_offset)), lastbr);
diffprev = (float) 100.0 *(ABSDIFF (prevbr, lastbr)) / (float) prevbr;
GST_DEBUG ("Difference with previous bitrate:%f", diffprev);
if (diffprev < 10.0) {
GST_DEBUG ("Difference < 10.0, Setting pcr_offset to %"
G_GUINT64_FORMAT, guess_offset);
cur->pcr_offset = guess_offset;
if (diffprev < 1.0) {
GST_DEBUG ("Difference < 1.0, Removing ESTIMATED flags");
cur->flags &= ~PCR_GROUP_FLAG_ESTIMATED;
}
}
/* Indicate the the previous group is before a wrapover */
prev->flags |= PCR_GROUP_FLAG_WRAPOVER;
} else {
guint64 resetprev;
/* Let's assume there was a PCR reset between the previous and current
* group
* [ prev ] ... x | x - reset ... [ current ]
*
* The estimated pcr_offset would then be
* = current.first - (x - reset) + (x - prev.first) + 100ms (for safety)
* = current.first + reset - prev.first + 100ms (for safety)
*/
/* In order to calculate the reset, we estimate what the PCR would have
* been by using prevbr */
/* FIXME : Which bitrate should we use ??? */
GST_DEBUG ("Using prevbr:%" G_GUINT64_FORMAT " and taking offsetdiff:%"
G_GUINT64_FORMAT, prevbr, cur->first_offset - prev->first_offset);
resetprev =
gst_util_uint64_scale (PCR_SECOND,
cur->first_offset - prev->first_offset, prevbr);
GST_DEBUG ("Estimated full PCR for offset %" G_GUINT64_FORMAT
", using prevbr:%"
GST_TIME_FORMAT, cur->first_offset,
GST_TIME_ARGS (PCRTIME_TO_GSTTIME (resetprev)));
cur->pcr_offset = prev->pcr_offset + resetprev + 100 * PCR_MSECOND;
GST_DEBUG ("Adjusted group PCR_offset to %" GST_TIME_FORMAT,
GST_TIME_ARGS (PCRTIME_TO_GSTTIME (cur->pcr_offset)));
/* Indicate the the previous group is before a reset */
prev->flags |= PCR_GROUP_FLAG_RESET;
}
} else {
/* FIXME : Detect gaps if bitrate difference is really too big ? */
cur->pcr_offset = prev->pcr_offset + cur->first_pcr - prev->first_pcr;
GST_DEBUG ("Assuming there is no gap, setting pcr_offset to %"
GST_TIME_FORMAT,
GST_TIME_ARGS (PCRTIME_TO_GSTTIME (cur->pcr_offset)));
/* Remove the reset and wrapover flag (if it was previously there) */
prev->flags &= ~PCR_GROUP_FLAG_RESET;
prev->flags &= ~PCR_GROUP_FLAG_WRAPOVER;
}
/* Remember prev for the next group evaluation */
prev = cur;
}
}
static PCROffsetGroup *
_new_group (guint64 pcr, guint64 offset, guint64 pcr_offset, guint flags)
{
PCROffsetGroup *group = g_slice_new0 (PCROffsetGroup);
GST_DEBUG ("Input PCR %" GST_TIME_FORMAT " offset:%" G_GUINT64_FORMAT
" pcr_offset:%" G_GUINT64_FORMAT " flags:%d",
GST_TIME_ARGS (PCRTIME_TO_GSTTIME (pcr)), offset, pcr_offset, flags);
group->flags = flags;
group->values = g_new0 (PCROffset, DEFAULT_ALLOCATED_OFFSET);
/* The first pcr/offset diff is always 0/0 */
group->values[0].pcr = group->values[0].offset = 0;
group->nb_allocated = DEFAULT_ALLOCATED_OFFSET;
/* Store the full values */
group->first_pcr = pcr;
group->first_offset = offset;
group->pcr_offset = pcr_offset;
GST_DEBUG ("Created group starting with pcr:%" GST_TIME_FORMAT " offset:%"
G_GUINT64_FORMAT " pcr_offset:%" GST_TIME_FORMAT,
GST_TIME_ARGS (PCRTIME_TO_GSTTIME (group->first_pcr)),
group->first_offset,
GST_TIME_ARGS (PCRTIME_TO_GSTTIME (group->pcr_offset)));
return group;
}
static void
_insert_group_after (MpegTSPCR * pcrtable, PCROffsetGroup * group,
PCROffsetGroup * prev)
{
if (prev == NULL) {
/* First group */
pcrtable->groups = g_list_prepend (pcrtable->groups, group);
} else {
GList *tmp, *toinsert, *prevlist = NULL, *nextlist = NULL;
/* Insert before next and prev */
for (tmp = pcrtable->groups; tmp; tmp = tmp->next) {
if (tmp->data == prev) {
prevlist = tmp;
nextlist = tmp->next;
break;
}
}
if (!prevlist) {
/* The non NULL prev given isn't in the list */
GST_WARNING ("Request to insert before a group which isn't in the list");
pcrtable->groups = g_list_prepend (pcrtable->groups, group);
} else {
toinsert = g_list_append (NULL, group);
toinsert->next = nextlist;
toinsert->prev = prevlist;
prevlist->next = toinsert;
if (nextlist)
nextlist->prev = toinsert;
}
}
}
static void
_use_group (MpegTSPCR * pcrtable, PCROffsetGroup * group)
{
PCROffsetCurrent *current = pcrtable->current;
memset (current, 0, sizeof (PCROffsetCurrent));
current->group = group;
current->pending[0] = group->values[group->last_value];
current->last_value = current->pending[0];
current->write = 1;
current->prev = group->values[group->last_value];
current->first_pcr = group->first_pcr;
current->first_offset = group->first_offset;
}
/* Create a new group with the specified values after prev
* Set current to that new group */
static void
_set_current_group (MpegTSPCR * pcrtable,
PCROffsetGroup * prev, guint64 pcr, guint64 offset, gboolean contiguous)
{
PCROffsetGroup *group;
guint flags = 0;
guint64 pcr_offset = 0;
/* Handle wraparound/gap (only if contiguous with previous group) */
if (contiguous) {
guint64 lastpcr = prev->first_pcr + prev->values[prev->last_value].pcr;
/* Set CLOSED flag on previous group and remember pcr_offset */
prev->flags |= PCR_GROUP_FLAG_CLOSED;
pcr_offset = prev->pcr_offset;
/* Wraparound ? */
if (lastpcr > pcr) {
/* In offset-mode, a PCR wraparound is only actually consistent if
* we have a very high confidence (99% right now, might need to change
* later) */
if (lastpcr - pcr > (PCR_MAX_VALUE * 99 / 100)) {
GST_WARNING ("WRAPAROUND detected. diff %" GST_TIME_FORMAT,
GST_TIME_ARGS (PCRTIME_TO_GSTTIME (lastpcr - pcr)));
/* The previous group closed at PCR_MAX_VALUE */
pcr_offset += PCR_MAX_VALUE - prev->first_pcr + pcr;
} else {
GST_WARNING ("RESET detected. diff %" GST_TIME_FORMAT,
GST_TIME_ARGS (PCRTIME_TO_GSTTIME (lastpcr - pcr)));
/* The previous group closed at the raw last_pcr diff (+100ms for safety) */
pcr_offset += prev->values[prev->last_value].pcr + 100 * PCR_MSECOND;
}
} else if (lastpcr < pcr - 500 * PCR_MSECOND) {
GST_WARNING ("GAP detected. diff %" GST_TIME_FORMAT,
GST_TIME_ARGS (PCRTIME_TO_GSTTIME (pcr - lastpcr)));
/* The previous group closed at the raw last_pcr diff (+500ms for safety) */
pcr_offset += prev->values[prev->last_value].pcr + 500 * PCR_MSECOND;
} else
/* Normal continuation (contiguous in time) */
pcr_offset += pcr - prev->first_pcr;
} else if (prev != NULL)
/* If we are not contiguous and it's not the first group, the pcr_offset
* will be estimated */
flags = PCR_GROUP_FLAG_ESTIMATED;
group = _new_group (pcr, offset, pcr_offset, flags);
_use_group (pcrtable, group);
_insert_group_after (pcrtable, group, prev);
if (!contiguous)
_reevaluate_group_pcr_offset (pcrtable, group);
}
static inline void
_append_group_values (PCROffsetGroup * group, PCROffset pcroffset)
{
group->last_value++;
/* Resize values if needed */
if (G_UNLIKELY (group->nb_allocated == group->last_value)) {
group->nb_allocated += DEFAULT_ALLOCATED_OFFSET;
group->values =
g_realloc (group->values, group->nb_allocated * sizeof (PCROffset));
}
group->values[group->last_value] = pcroffset;
GST_DEBUG ("First PCR:%" GST_TIME_FORMAT " offset:%" G_GUINT64_FORMAT
" PCR_offset:%" GST_TIME_FORMAT,
GST_TIME_ARGS (PCRTIME_TO_GSTTIME (group->first_pcr)),
group->first_offset,
GST_TIME_ARGS (PCRTIME_TO_GSTTIME (group->pcr_offset)));
GST_DEBUG ("Last PCR: +%" GST_TIME_FORMAT " offset: +%u",
GST_TIME_ARGS (PCRTIME_TO_GSTTIME (pcroffset.pcr)), pcroffset.offset);
}
/* Move last values from current (if any) to the current group
* and reset current.
* Note: This does not set the CLOSED flag (since we have no next
* contiguous group) */
static void
_close_current_group (MpegTSPCR * pcrtable)
{
PCROffsetCurrent *current = pcrtable->current;
PCROffsetGroup *group = current->group;
if (group == NULL)
return;
GST_DEBUG ("Closing group and resetting current");
/* Store last values */
_append_group_values (group, current->pending[current->last]);
memset (current, 0, sizeof (PCROffsetCurrent));
/* And re-evaluate all groups */
}
static void
record_pcr (MpegTSPacketizer2 * packetizer, MpegTSPCR * pcrtable,
guint64 pcr, guint64 offset)
{
PCROffsetCurrent *current = pcrtable->current;
guint32 corpcr, coroffset;
packetizer->nb_seen_offsets += 1;
/* FIXME : Invert logic later (probability is higher that we have a
* current estimator) */
/* Check for current */
if (G_UNLIKELY (current->group == NULL)) {
PCROffsetGroup *prev = NULL;
GList *tmp;
/* No current estimator. This happens for the initial value, or after
* discont and flushes. Figure out where we need to record this position.
*
* Possible choices:
* 1) No groups at all:
* Create a new group with pcr/offset
* Initialize current to that group
* 2) Entirely within an existing group
* bail out (FIXME: Make this detection faster)
* 3) Not in any group
* Create a new group with pcr/offset at the right position
* Initialize current to that group
*/
GST_DEBUG ("No current window estimator, Checking for group to use");
for (tmp = pcrtable->groups; tmp; tmp = tmp->next) {
PCROffsetGroup *group = (PCROffsetGroup *) tmp->data;
GST_DEBUG ("First PCR:%" GST_TIME_FORMAT " offset:%" G_GUINT64_FORMAT
" PCR_offset:%" GST_TIME_FORMAT,
GST_TIME_ARGS (PCRTIME_TO_GSTTIME (group->first_pcr)),
group->first_offset,
GST_TIME_ARGS (PCRTIME_TO_GSTTIME (group->pcr_offset)));
GST_DEBUG ("Last PCR: +%" GST_TIME_FORMAT " offset: +%u",
GST_TIME_ARGS (PCRTIME_TO_GSTTIME (group->values[group->
last_value].pcr)),
group->values[group->last_value].offset);
/* Check if before group */
if (offset < group->first_offset) {
GST_DEBUG ("offset is before that group");
break;
}
/* Check if within group */
if (offset <=
(group->values[group->last_value].offset + group->first_offset)) {
GST_DEBUG ("Already observed PCR offset %" G_GUINT64_FORMAT, offset);
return;
}
/* Check if just after group (i.e. continuation of it) */
if (!(group->flags & PCR_GROUP_FLAG_CLOSED) &&
pcr - group->first_pcr - group->values[group->last_value].pcr <=
100 * PCR_MSECOND) {
GST_DEBUG ("Continuation of existing group");
_use_group (pcrtable, group);
return;
}
/* Else after group */
prev = group;
}
_set_current_group (pcrtable, prev, pcr, offset, FALSE);
return;
}
corpcr = pcr - current->first_pcr;
coroffset = offset - current->first_offset;
/* FIXME : Detect if we've gone into the next group !
* FIXME : Close group when that happens */
GST_DEBUG ("first:%d, last:%d, write:%d", current->first, current->last,
current->write);
GST_DEBUG ("First PCR:%" GST_TIME_FORMAT " offset:%" G_GUINT64_FORMAT,
GST_TIME_ARGS (PCRTIME_TO_GSTTIME (current->first_pcr)),
current->first_offset);
GST_DEBUG ("Last PCR: +%" GST_TIME_FORMAT " offset: +%u",
GST_TIME_ARGS (PCRTIME_TO_GSTTIME (current->pending[current->last].pcr)),
current->pending[current->last].pcr);
GST_DEBUG ("To add (corrected) PCR:%" GST_TIME_FORMAT " offset:%u",
GST_TIME_ARGS (PCRTIME_TO_GSTTIME (corpcr)), coroffset);
/* Do we need to close the current group ? */
/* Check for wrapover/discont */
if (G_UNLIKELY (corpcr < current->pending[current->last].pcr)) {
/* FIXME : ignore very small deltas (< 500ms ?) which are most likely
* stray values */
GST_DEBUG
("PCR smaller than previously observed one, handling discont/wrapover");
/* Take values from current and put them in the current group (closing it) */
/* Create new group with new pcr/offset just after the current group
* and mark it as a wrapover */
/* Initialize current to that group with new values */
_append_group_values (current->group, current->pending[current->last]);
_set_current_group (pcrtable, current->group, pcr, offset, TRUE);
return;
}
/* If PCR diff is greater than 500ms, create new group */
if (G_UNLIKELY (corpcr - current->pending[current->last].pcr >
500 * PCR_MSECOND)) {
GST_DEBUG ("New PCR more than 500ms away, handling discont");
/* Take values from current and put them in the current group (closing it) */
/* Create new group with pcr/offset just after the current group
* and mark it as a discont */
/* Initialize current to that group with new values */
_append_group_values (current->group, current->pending[current->last]);
_set_current_group (pcrtable, current->group, pcr, offset, TRUE);
return;
}
if (G_UNLIKELY (corpcr == current->last_value.pcr)) {
GST_DEBUG ("Ignoring same PCR (stream is drunk)");
return;
}
/* update current window */
current->pending[current->write].pcr = corpcr;
current->pending[current->write].offset = coroffset;
current->last_value = current->pending[current->write];
current->last = (current->last + 1) % PCR_BITRATE_NEEDED;
current->write = (current->write + 1) % PCR_BITRATE_NEEDED;
GST_DEBUG ("first:%d, last:%d, write:%d", current->first, current->last,
current->write);
GST_DEBUG ("First PCR:%" GST_TIME_FORMAT " offset:%" G_GUINT64_FORMAT,
GST_TIME_ARGS (PCRTIME_TO_GSTTIME (current->first_pcr)),
current->first_offset);
GST_DEBUG ("Last PCR: +%" GST_TIME_FORMAT " offset: +%u",
GST_TIME_ARGS (PCRTIME_TO_GSTTIME (current->pending[current->last].pcr)),
current->pending[current->last].offset);
/* If we haven't stored enough values, bail out */
if (current->write != current->first) {
GST_DEBUG
("Not enough observations to calculate bitrate (first:%d, last:%d)",
current->first, current->last);
return;
}
/* If we are at least 1s away from reference value AND we have filled our
* window, we can start comparing bitrates */
if (current->pending[current->first].pcr - current->prev.pcr > PCR_SECOND) {
/* Calculate window bitrate */
current->cur_bitrate = gst_util_uint64_scale (PCR_SECOND,
current->pending[current->last].offset -
current->pending[current->first].offset,
current->pending[current->last].pcr -
current->pending[current->first].pcr);
GST_DEBUG ("Current bitrate is now %" G_GUINT64_FORMAT,
current->cur_bitrate);
/* Calculate previous bitrate */
current->prev_bitrate =
gst_util_uint64_scale (PCR_SECOND,
current->pending[current->first].offset - current->prev.offset,
current->pending[current->first].pcr - current->prev.pcr);
GST_DEBUG ("Previous group bitrate now %" G_GUINT64_FORMAT,
current->prev_bitrate);
/* FIXME : Better bitrate changes ? Currently 10% changes */
if (ABSDIFF (current->cur_bitrate,
current->prev_bitrate) * 10 > current->prev_bitrate) {
GST_DEBUG ("Current bitrate changed by more than 10%% (old:%"
G_GUINT64_FORMAT " new:%" G_GUINT64_FORMAT ")", current->prev_bitrate,
current->cur_bitrate);
/* If we detected a change in bitrate, this means that
* d(first - prev) is a different bitrate than d(last - first).
*
* Two conclusions can be made:
* 1) d(first - prev) is a complete bitrate "chain" (values between the
* reference value and first pending value have consistent bitrate).
* 2) next values (from second pending value onwards) will no longer have
* the same bitrate.
*
* The question remains as to how long the new bitrate change is going to
* last for (it might be short or longer term). For this we need to restart
* bitrate estimation.
*
* * We move over first to the last value of group (a new chain ends and
* starts from there)
* * We remember that last group value as our new window reference
* * We restart our window filing from the last observed value
*
* Once our new window is filled we will end up in two different scenarios:
* 1) Either the bitrate change was consistent, and therefore the bitrate
* will have remained constant over at least 2 window length
* 2) The bitrate change was very short (1 window duration) and we will
* close that chain and restart again.
* X) And of course if any discont/gaps/wrapover happen in the meantime they
* will also close the group.
*/
_append_group_values (current->group, current->pending[current->first]);
current->prev = current->pending[current->first];
current->first = current->last;
current->write = (current->first + 1) % PCR_BITRATE_NEEDED;
return;
}
}
/* Update read position */
current->first = (current->first + 1) % PCR_BITRATE_NEEDED;
}
/* convert specified offset into stream time */
GstClockTime
mpegts_packetizer_offset_to_ts (MpegTSPacketizer2 * packetizer,
guint64 offset, guint16 pid)
{
PCROffsetGroup *last;
MpegTSPCR *pcrtable;
GList *tmp;
GstClockTime res;
guint64 lastpcr, lastoffset;
GST_DEBUG ("offset %" G_GUINT64_FORMAT, offset);
if (G_UNLIKELY (!packetizer->calculate_offset))
return GST_CLOCK_TIME_NONE;
if (G_UNLIKELY (packetizer->refoffset == -1))
return GST_CLOCK_TIME_NONE;
if (G_UNLIKELY (offset < packetizer->refoffset))
return GST_CLOCK_TIME_NONE;
pcrtable = get_pcr_table (packetizer, pid);
if (g_list_length (pcrtable->groups) < 2) {
GST_WARNING ("Not enough observations to return a duration estimate");
return GST_CLOCK_TIME_NONE;
}
/* FIXME : Refine this later to use neighbouring groups */
tmp = g_list_last (pcrtable->groups);
last = tmp->data;
if (G_UNLIKELY (last->flags & PCR_GROUP_FLAG_ESTIMATED))
_reevaluate_group_pcr_offset (pcrtable, last);
/* lastpcr is the full value in PCR from the first first chunk of data */
lastpcr = last->values[last->last_value].pcr + last->pcr_offset;
/* lastoffset is the full offset from the first chunk of data */
lastoffset =
last->values[last->last_value].offset + last->first_offset -
packetizer->refoffset;
GST_DEBUG ("lastpcr:%" GST_TIME_FORMAT " lastoffset:%" G_GUINT64_FORMAT,
GST_TIME_ARGS (PCRTIME_TO_GSTTIME (lastpcr)), lastoffset);
/* Convert byte difference into time difference (and transformed from 27MHz to 1GHz) */
res =
PCRTIME_TO_GSTTIME (gst_util_uint64_scale (offset - packetizer->refoffset,
lastpcr, lastoffset));
GST_DEBUG ("Returning timestamp %" GST_TIME_FORMAT " for offset %"
G_GUINT64_FORMAT, GST_TIME_ARGS (res), offset);
return res;
}
/* Input : local PTS (in GHz units)
* Return : Stream time (in GHz units) */
GstClockTime
mpegts_packetizer_pts_to_ts (MpegTSPacketizer2 * packetizer,
GstClockTime pts, guint16 pcr_pid)
{
GstClockTime res = GST_CLOCK_TIME_NONE;
MpegTSPCR *pcrtable = get_pcr_table (packetizer, pcr_pid);
/* Use clock skew if present */
if (packetizer->calculate_skew
&& GST_CLOCK_TIME_IS_VALID (pcrtable->base_time)) {
GST_DEBUG ("pts %" G_GUINT64_FORMAT " base_pcrtime:%" G_GUINT64_FORMAT
" base_time:%" GST_TIME_FORMAT, pts, pcrtable->base_pcrtime,
GST_TIME_ARGS (pcrtable->base_time));
res =
pts + pcrtable->pcroffset - pcrtable->base_pcrtime +
pcrtable->base_time + pcrtable->skew;
} else if (packetizer->calculate_offset && pcrtable->groups) {
gint64 refpcr = G_MAXINT64, refpcroffset;
PCROffsetGroup *group = pcrtable->current->group;
/* Generic calculation:
* Stream Time = PTS - first group PCR + group PCR_offset
*
* In case of wrapover:
* Stream Time = PTS + MAX_PCR - first group PCR + group PCR_offset
* (which we actually do by using first group PCR -= MAX_PCR in order
* to end up with the same calculation as for non-wrapover) */
if (group) {
/* If we have a current group the value is pretty much guaranteed */
GST_DEBUG ("Using current First PCR:%" GST_TIME_FORMAT " offset:%"
G_GUINT64_FORMAT " PCR_offset:%" GST_TIME_FORMAT,
GST_TIME_ARGS (PCRTIME_TO_GSTTIME (group->first_pcr)),
group->first_offset,
GST_TIME_ARGS (PCRTIME_TO_GSTTIME (group->pcr_offset)));
refpcr = group->first_pcr;
refpcroffset = group->pcr_offset;
if (pts < PCRTIME_TO_GSTTIME (refpcr))
refpcr -= PCR_MAX_VALUE;
} else {
GList *tmp;
/* Otherwise, find a suitable group */
GST_DEBUG ("Find group for current offset %" G_GUINT64_FORMAT,
packetizer->offset);
for (tmp = pcrtable->groups; tmp; tmp = tmp->next) {
PCROffsetGroup *tgroup = tmp->data;
GST_DEBUG ("Trying First PCR:%" GST_TIME_FORMAT " offset:%"
G_GUINT64_FORMAT " PCR_offset:%" GST_TIME_FORMAT,
GST_TIME_ARGS (PCRTIME_TO_GSTTIME (tgroup->first_pcr)),
tgroup->first_offset,
GST_TIME_ARGS (PCRTIME_TO_GSTTIME (tgroup->pcr_offset)));
/* Gone too far ? */
if (tgroup->first_offset > packetizer->offset) {
/* If there isn't a pending reset, use that value */
if (group) {
GST_DEBUG ("PTS is %" GST_TIME_FORMAT " into group",
GST_TIME_ARGS (pts - PCRTIME_TO_GSTTIME (group->first_pcr)));
}
break;
}
group = tgroup;
/* In that group ? */
if (group->first_offset + group->values[group->last_value].offset >
packetizer->offset) {
GST_DEBUG ("PTS is %" GST_TIME_FORMAT " into group",
GST_TIME_ARGS (pts - PCRTIME_TO_GSTTIME (group->first_pcr)));
break;
}
}
if (group && !(group->flags & PCR_GROUP_FLAG_RESET)) {
GST_DEBUG ("Using group !");
refpcr = group->first_pcr;
refpcroffset = group->pcr_offset;
if (pts < refpcr)
refpcr -= PCR_MAX_VALUE;
}
}
if (refpcr != G_MAXINT64)
res = pts - PCRTIME_TO_GSTTIME (refpcr - refpcroffset);
else
GST_WARNING ("No groups, can't calculate timestamp");
} else
GST_WARNING ("Not enough information to calculate proper timestamp");
GST_DEBUG ("Returning timestamp %" GST_TIME_FORMAT " for pts %"
GST_TIME_FORMAT " pcr_pid:0x%04x", GST_TIME_ARGS (res),
GST_TIME_ARGS (pts), pcr_pid);
return res;
}
/* Stream time to offset */
guint64
mpegts_packetizer_ts_to_offset (MpegTSPacketizer2 * packetizer,
GstClockTime ts, guint16 pcr_pid)
{
MpegTSPCR *pcrtable;
guint64 res;
PCROffsetGroup *nextgroup = NULL, *prevgroup = NULL;
guint64 querypcr, firstpcr, lastpcr, firstoffset, lastoffset;
PCROffsetCurrent *current;
GList *tmp;
if (!packetizer->calculate_offset)
return -1;
pcrtable = get_pcr_table (packetizer, pcr_pid);
if (pcrtable->groups == NULL)
return -1;
querypcr = GSTTIME_TO_PCRTIME (ts);
GST_DEBUG ("Searching offset for ts %" GST_TIME_FORMAT, GST_TIME_ARGS (ts));
/* First check if we're within the current pending group */
current = pcrtable->current;
if (current && current->group && (querypcr >= current->group->pcr_offset) &&
querypcr - current->group->pcr_offset <=
current->pending[current->last].pcr) {
GST_DEBUG ("pcr is in current group");
nextgroup = current->group;
goto calculate_points;
}
/* Find the neighbouring groups */
for (tmp = pcrtable->groups; tmp; tmp = tmp->next) {
nextgroup = (PCROffsetGroup *) tmp->data;
GST_DEBUG ("Trying group PCR %" GST_TIME_FORMAT " (offset %"
G_GUINT64_FORMAT " pcr_offset %" GST_TIME_FORMAT,
GST_TIME_ARGS (PCRTIME_TO_GSTTIME (nextgroup->first_pcr)),
nextgroup->first_offset,
GST_TIME_ARGS (PCRTIME_TO_GSTTIME (nextgroup->pcr_offset)));
/* Check if we've gone too far */
if (nextgroup->pcr_offset > querypcr) {
GST_DEBUG ("pcr is before that group");
break;
}
if (tmp->next == NULL) {
GST_DEBUG ("pcr is beyond last group");
break;
}
prevgroup = nextgroup;
/* Maybe it's in this group */
if (nextgroup->values[nextgroup->last_value].pcr +
nextgroup->pcr_offset >= querypcr) {
GST_DEBUG ("pcr is in that group");
break;
}
}
calculate_points:
GST_DEBUG ("nextgroup:%p, prevgroup:%p", nextgroup, prevgroup);
if (nextgroup == prevgroup || prevgroup == NULL) {
/* We use the current group to calculate position:
* * if the PCR is within this group
* * if there is only one group to use for calculation
*/
GST_DEBUG ("In group or after last one");
lastoffset = firstoffset = nextgroup->first_offset;
lastpcr = firstpcr = nextgroup->pcr_offset;
if (current && nextgroup == current->group) {
lastoffset += current->pending[current->last].offset;
lastpcr += current->pending[current->last].pcr;
} else {
lastoffset += nextgroup->values[nextgroup->last_value].offset;
lastpcr += nextgroup->values[nextgroup->last_value].pcr;
}
} else if (prevgroup) {
GST_DEBUG ("Between group");
lastoffset = nextgroup->first_offset;
lastpcr = nextgroup->pcr_offset;
firstoffset =
prevgroup->values[prevgroup->last_value].offset +
prevgroup->first_offset;
firstpcr =
prevgroup->values[prevgroup->last_value].pcr + prevgroup->pcr_offset;
} else {
GST_WARNING ("Not enough information to calculate offset");
return -1;
}
GST_DEBUG ("Using prev PCR %" G_GUINT64_FORMAT " offset %" G_GUINT64_FORMAT,
firstpcr, firstoffset);
GST_DEBUG ("Using last PCR %" G_GUINT64_FORMAT " offset %" G_GUINT64_FORMAT,
lastpcr, lastoffset);
res = firstoffset;
if (lastpcr != firstpcr)
res += gst_util_uint64_scale (querypcr - firstpcr,
lastoffset - firstoffset, lastpcr - firstpcr);
GST_DEBUG ("Returning offset %" G_GUINT64_FORMAT " for ts %"
GST_TIME_FORMAT, res, GST_TIME_ARGS (ts));
return res;
}
void
mpegts_packetizer_set_reference_offset (MpegTSPacketizer2 * packetizer,
guint64 refoffset)
{
GST_DEBUG ("Setting reference offset to %" G_GUINT64_FORMAT, refoffset);
packetizer->refoffset = refoffset;
}
void
mpegts_packetizer_set_current_pcr_offset (MpegTSPacketizer2 * packetizer,
GstClockTime offset, guint16 pcr_pid)
{
guint64 pcr_offset;
gint64 delta;
MpegTSPCR *pcrtable;
PCROffsetGroup *group;
GList *tmp;
gboolean apply = FALSE;
/* fast path */
pcrtable = get_pcr_table (packetizer, pcr_pid);
if (pcrtable == NULL || pcrtable->current->group == NULL)
return;
pcr_offset = GSTTIME_TO_PCRTIME (offset);
group = pcrtable->current->group;
GST_DEBUG ("Current group PCR %" GST_TIME_FORMAT " (offset %"
G_GUINT64_FORMAT " pcr_offset %" GST_TIME_FORMAT,
GST_TIME_ARGS (PCRTIME_TO_GSTTIME (group->first_pcr)),
group->first_offset,
GST_TIME_ARGS (PCRTIME_TO_GSTTIME (group->pcr_offset)));
/* Remember the difference between previous initial pcr_offset and
* new initial pcr_offset */
delta = pcr_offset - group->pcr_offset;
GST_DEBUG ("Shifting groups by %" GST_TIME_FORMAT
" for new initial pcr_offset %" GST_TIME_FORMAT,
GST_TIME_ARGS (PCRTIME_TO_GSTTIME (delta)), GST_TIME_ARGS (offset));
for (tmp = pcrtable->groups; tmp; tmp = tmp->next) {
PCROffsetGroup *tgroup = (tmp->data);
if (tgroup == group)
apply = TRUE;
if (apply) {
tgroup->pcr_offset += delta;
GST_DEBUG ("Update group PCR %" GST_TIME_FORMAT " (offset %"
G_GUINT64_FORMAT " pcr_offset %" GST_TIME_FORMAT,
GST_TIME_ARGS (PCRTIME_TO_GSTTIME (tgroup->first_pcr)),
tgroup->first_offset,
GST_TIME_ARGS (PCRTIME_TO_GSTTIME (tgroup->pcr_offset)));
} else
GST_DEBUG ("Not modifying group PCR %" GST_TIME_FORMAT " (offset %"
G_GUINT64_FORMAT " pcr_offset %" GST_TIME_FORMAT,
GST_TIME_ARGS (PCRTIME_TO_GSTTIME (tgroup->first_pcr)),
tgroup->first_offset,
GST_TIME_ARGS (PCRTIME_TO_GSTTIME (tgroup->pcr_offset)));
}
}
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