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gstreamer/gst/mpegtsdemux/mpegtspacketizer.c
Edward Hervey 3b60f88437 mpegtspacketizer: Look harder for next sync position 
If ever we lose sync, we were just checking for the next 0x47 marker ...
which might actually happen within a mpeg-ts packet.

Instead check for 3 repeating 0x47 at the expected packet size interval,
which the same logic we use when we initially look for the packet size.
2013-08-02 10:41:25 +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 / (27000))
#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
#define MPEGTS_PACKETIZER_GET_PRIVATE(obj) \
(G_TYPE_INSTANCE_GET_PRIVATE ((obj), GST_TYPE_MPEGTS_PACKETIZER, MpegTSPacketizerPrivate))
static void _init_local (void);
G_DEFINE_TYPE_EXTENDED (MpegTSPacketizer2, mpegts_packetizer, G_TYPE_OBJECT, 0,
_init_local ());
/* Maximum number of MpegTSPcr
* 256 should be sufficient for most multiplexes */
#define MAX_PCR_OBS_CHANNELS 256
typedef struct _MpegTSPCR
{
guint16 pid;
/* Following variables are only active/used when
* calculate_skew is TRUE */
GstClockTime base_time;
GstClockTime base_pcrtime;
GstClockTime prev_out_time;
GstClockTime prev_in_time;
GstClockTime last_pcrtime;
gint64 window[MAX_WINDOW];
guint window_pos;
guint window_size;
gboolean window_filling;
gint64 window_min;
gint64 skew;
gint64 prev_send_diff;
/* Offset to apply to PCR to handle wraparounds */
guint64 pcroffset;
/* Used for bitrate calculation */
/* FIXME : Replace this later on with a balanced tree or sequence */
guint64 first_offset;
guint64 first_pcr;
GstClockTime first_pcr_ts;
guint64 last_offset;
guint64 last_pcr;
GstClockTime last_pcr_ts;
} MpegTSPCR;
struct _MpegTSPacketizerPrivate
{
/* Shortcuts for adapter usage */
guint available;
guint8 *mapped;
guint offset;
guint mapped_size;
/* Reference offset */
guint64 refoffset;
guint nb_seen_offsets;
/* Last inputted timestamp */
GstClockTime last_in_time;
/* offset to observations table */
guint8 pcrtablelut[0x2000];
MpegTSPCR *observations[MAX_PCR_OBS_CHANNELS];
guint8 lastobsid;
};
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 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)
{
MpegTSPacketizerPrivate *priv = packetizer->priv;
MpegTSPCR *res;
res = priv->observations[priv->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 */
priv->observations[priv->lastobsid] = res;
/* Update the pcrtablelut */
priv->pcrtablelut[pid] = priv->lastobsid;
/* And increment the last know slot */
priv->lastobsid++;
/* Finally set the default values */
res->pid = pid;
res->first_offset = -1;
res->first_pcr = -1;
res->first_pcr_ts = GST_CLOCK_TIME_NONE;
res->last_offset = -1;
res->last_pcr = -1;
res->last_pcr_ts = GST_CLOCK_TIME_NONE;
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;
}
return res;
}
static void
flush_observations (MpegTSPacketizer2 * packetizer)
{
MpegTSPacketizerPrivate *priv = packetizer->priv;
gint i;
for (i = 0; i < priv->lastobsid; i++) {
g_free (priv->observations[i]);
priv->observations[i] = NULL;
}
memset (priv->pcrtablelut, 0xff, 0x2000);
priv->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 subtale");
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;
g_type_class_add_private (klass, sizeof (MpegTSPacketizerPrivate));
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)
{
MpegTSPacketizerPrivate *priv;
priv = packetizer->priv = MPEGTS_PACKETIZER_GET_PRIVATE (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;
priv->available = 0;
priv->mapped = NULL;
priv->mapped_size = 0;
priv->offset = 0;
memset (priv->pcrtablelut, 0xff, 0x2000);
memset (priv->observations, 0x0, sizeof (priv->observations));
priv->lastobsid = 0;
priv->nb_seen_offsets = 0;
priv->refoffset = -1;
priv->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 (FLAGS_HAS_AFC (packet->scram_afc_cc)) {
/* no payload, adaptation field of 183 bytes */
if (length != 183) {
GST_DEBUG ("PID %d afc == 0x%02x and length %d != 183",
packet->pid, packet->scram_afc_cc & 0x30, length);
}
} else if (length > 182) {
GST_DEBUG ("PID %d afc == 0x%02x and length %d > 182",
packet->pid, packet->scram_afc_cc & 0x30, length);
}
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->priv->last_in_time)) {
pcrtable = get_pcr_table (packetizer, packet->pid);
calculate_skew (pcrtable, packet->pcr, packetizer->priv->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)
{
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->priv->available = 0;
packetizer->priv->mapped = NULL;
packetizer->priv->mapped_size = 0;
packetizer->priv->offset = 0;
packetizer->priv->last_in_time = GST_CLOCK_TIME_NONE;
}
void
mpegts_packetizer_flush (MpegTSPacketizer2 * packetizer, gboolean hard)
{
GST_DEBUG ("Flushing");
if (packetizer->streams) {
int i;
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->priv->available = 0;
packetizer->priv->mapped = NULL;
packetizer->priv->offset = 0;
packetizer->priv->mapped_size = 0;
packetizer->priv->last_in_time = GST_CLOCK_TIME_NONE;
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);
packetizer->priv->available += gst_buffer_get_size (buffer);
/* If buffer timestamp is valid, store it */
if (GST_CLOCK_TIME_IS_VALID (GST_BUFFER_TIMESTAMP (buffer)))
packetizer->priv->last_in_time = GST_BUFFER_TIMESTAMP (buffer);
}
static gboolean
mpegts_try_discover_packet_size (MpegTSPacketizer2 * packetizer)
{
guint8 *dest;
int i, pos = -1, j;
static const guint psizes[] = {
MPEGTS_NORMAL_PACKETSIZE,
MPEGTS_M2TS_PACKETSIZE,
MPEGTS_DVB_ASI_PACKETSIZE,
MPEGTS_ATSC_PACKETSIZE
};
dest = g_malloc (MPEGTS_MAX_PACKETSIZE * 4);
/* wait for 3 sync bytes */
while (packetizer->priv->available >= MPEGTS_MAX_PACKETSIZE * 4) {
/* check for sync bytes */
gst_adapter_copy (packetizer->adapter, dest, 0, MPEGTS_MAX_PACKETSIZE * 4);
/* find first sync byte */
pos = -1;
for (i = 0; i < MPEGTS_MAX_PACKETSIZE; i++) {
if (dest[i] == PACKET_SYNC_BYTE) {
for (j = 0; j < 4; j++) {
guint packetsize = psizes[j];
/* check each of the packet size possibilities in turn */
if (dest[i] == PACKET_SYNC_BYTE
&& dest[i + packetsize] == PACKET_SYNC_BYTE
&& dest[i + packetsize * 2] == PACKET_SYNC_BYTE
&& dest[i + packetsize * 3] == PACKET_SYNC_BYTE) {
packetizer->packet_size = packetsize;
if (packetsize == MPEGTS_M2TS_PACKETSIZE)
pos = i - 4;
else
pos = i;
break;
}
}
break;
}
}
if (packetizer->packet_size)
break;
/* Skip MPEGTS_MAX_PACKETSIZE */
gst_adapter_flush (packetizer->adapter, MPEGTS_MAX_PACKETSIZE);
packetizer->priv->available -= MPEGTS_MAX_PACKETSIZE;
packetizer->offset += MPEGTS_MAX_PACKETSIZE;
}
g_free (dest);
if (packetizer->packet_size) {
GST_DEBUG ("have packetsize detected: %d of %u bytes",
packetizer->packet_size, packetizer->packet_size);
/* flush to sync byte */
if (pos > 0) {
GST_DEBUG ("Flushing out %d bytes", pos);
gst_adapter_flush (packetizer->adapter, pos);
packetizer->offset += pos;
packetizer->priv->available -= MPEGTS_MAX_PACKETSIZE;
}
} else {
/* drop invalid data and move to the next possible packets */
GST_DEBUG ("Could not determine packet size");
}
return packetizer->packet_size;
}
gboolean
mpegts_packetizer_has_packets (MpegTSPacketizer2 * packetizer)
{
if (G_UNLIKELY (!packetizer->packet_size)) {
if (!mpegts_try_discover_packet_size (packetizer))
return FALSE;
}
return packetizer->priv->available >= packetizer->packet_size;
}
MpegTSPacketizerPacketReturn
mpegts_packetizer_next_packet (MpegTSPacketizer2 * packetizer,
MpegTSPacketizerPacket * packet)
{
MpegTSPacketizerPrivate *priv = packetizer->priv;
guint skip;
guint sync_offset;
guint packet_size;
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;
}
while (priv->available >= packet_size) {
if (priv->mapped == NULL) {
priv->mapped_size = priv->available;
priv->mapped =
(guint8 *) gst_adapter_map (packetizer->adapter, priv->mapped_size);
priv->offset = 0;
}
/* M2TS packets don't start with the sync byte, all other variants do */
sync_offset = priv->offset;
if (packet_size == MPEGTS_M2TS_PACKETSIZE)
sync_offset += 4;
/* Check sync byte */
if (G_LIKELY (priv->mapped[sync_offset] == 0x47)) {
/* 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 = priv->mapped + sync_offset;
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);
goto got_valid_packet;
}
GST_LOG ("Lost sync %d", packet_size);
/* Find the 0x47 in the buffer (and require at least 2 checks) */
for (; sync_offset < priv->mapped_size + 2 * packet_size; sync_offset++)
if (priv->mapped[sync_offset] == 0x47 &&
priv->mapped[sync_offset + packet_size] == 0x47 &&
priv->mapped[sync_offset + 2 * packet_size] == 0x47)
break;
/* Pop out the remaining data... */
skip = sync_offset - priv->offset;
if (packet_size == MPEGTS_M2TS_PACKETSIZE)
skip -= 4;
priv->available -= skip;
priv->offset += skip;
packetizer->offset += skip;
if (G_UNLIKELY (priv->available < packet_size)) {
GST_DEBUG ("Flushing %d bytes out", priv->offset);
gst_adapter_flush (packetizer->adapter, priv->offset);
priv->mapped = NULL;
}
}
return PACKET_NEED_MORE;
got_valid_packet:
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) {
packetizer->priv->offset += packetizer->packet_size;
packetizer->priv->available -= packetizer->packet_size;
if (G_UNLIKELY (packetizer->priv->available < packetizer->packet_size)) {
gst_adapter_flush (packetizer->adapter, packetizer->priv->offset);
packetizer->priv->mapped = NULL;
}
}
return ret;
}
void
mpegts_packetizer_clear_packet (MpegTSPacketizer2 * packetizer,
MpegTSPacketizerPacket * packet)
{
guint8 packet_size = packetizer->packet_size;
MpegTSPacketizerPrivate *priv = packetizer->priv;
priv->offset += packet_size;
priv->available -= packet_size;
if (G_UNLIKELY (priv->mapped && priv->available < packet_size)) {
gst_adapter_flush (packetizer->adapter, priv->offset);
priv->mapped = NULL;
}
}
/*
* 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
record_pcr (MpegTSPacketizer2 * packetizer, MpegTSPCR * pcrtable,
guint64 pcr, guint64 offset)
{
MpegTSPacketizerPrivate *priv = packetizer->priv;
/* Check against first PCR */
if (pcrtable->first_pcr == -1 || pcrtable->first_offset > offset) {
GST_DEBUG ("Recording first value. PCR:%" G_GUINT64_FORMAT " offset:%"
G_GUINT64_FORMAT " pcr_pid:0x%04x", pcr, offset, pcrtable->pid);
pcrtable->first_pcr = pcr;
pcrtable->first_pcr_ts = PCRTIME_TO_GSTTIME (pcr);
pcrtable->first_offset = offset;
priv->nb_seen_offsets++;
} else
/* If we didn't update the first PCR, let's check against last PCR */
if (pcrtable->last_pcr == -1 || pcrtable->last_offset < offset) {
GST_DEBUG ("Recording last value. PCR:%" G_GUINT64_FORMAT " offset:%"
G_GUINT64_FORMAT " pcr_pid:0x%04x", pcr, offset, pcrtable->pid);
if (G_UNLIKELY (pcrtable->first_pcr != -1 && pcr < pcrtable->first_pcr)) {
GST_DEBUG ("rollover detected");
pcr += PCR_MAX_VALUE;
}
pcrtable->last_pcr = pcr;
pcrtable->last_pcr_ts = PCRTIME_TO_GSTTIME (pcr);
pcrtable->last_offset = offset;
priv->nb_seen_offsets++;
}
}
guint
mpegts_packetizer_get_seen_pcr (MpegTSPacketizer2 * packetizer)
{
return packetizer->priv->nb_seen_offsets;
}
GstClockTime
mpegts_packetizer_offset_to_ts (MpegTSPacketizer2 * packetizer,
guint64 offset, guint16 pid)
{
MpegTSPacketizerPrivate *priv = packetizer->priv;
MpegTSPCR *pcrtable;
GstClockTime res;
if (G_UNLIKELY (!packetizer->calculate_offset))
return GST_CLOCK_TIME_NONE;
if (G_UNLIKELY (priv->refoffset == -1))
return GST_CLOCK_TIME_NONE;
if (G_UNLIKELY (offset < priv->refoffset))
return GST_CLOCK_TIME_NONE;
pcrtable = get_pcr_table (packetizer, pid);
if (G_UNLIKELY (pcrtable->last_offset <= pcrtable->first_offset))
return GST_CLOCK_TIME_NONE;
/* Convert byte difference into time difference */
res = PCRTIME_TO_GSTTIME (gst_util_uint64_scale (offset - priv->refoffset,
pcrtable->last_pcr - pcrtable->first_pcr,
pcrtable->last_offset - pcrtable->first_offset));
GST_DEBUG ("Returning timestamp %" GST_TIME_FORMAT " for offset %"
G_GUINT64_FORMAT, GST_TIME_ARGS (res), offset);
return res;
}
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 not, use pcr observations */
if (packetizer->calculate_offset && pcrtable->first_pcr != -1) {
/* Rollover */
if (G_UNLIKELY (pts < pcrtable->first_pcr_ts))
pts += MPEGTIME_TO_GSTTIME (PTS_DTS_MAX_VALUE);
res = pts - pcrtable->first_pcr_ts;
} 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;
}
guint64
mpegts_packetizer_ts_to_offset (MpegTSPacketizer2 * packetizer,
GstClockTime ts, guint16 pcr_pid)
{
MpegTSPacketizerPrivate *priv = packetizer->priv;
MpegTSPCR *pcrtable;
guint64 res;
if (!packetizer->calculate_offset)
return -1;
pcrtable = get_pcr_table (packetizer, pcr_pid);
if (pcrtable->first_pcr == -1)
return -1;
GST_DEBUG ("ts(pcr) %" G_GUINT64_FORMAT " first_pcr:%" G_GUINT64_FORMAT,
GSTTIME_TO_MPEGTIME (ts), pcrtable->first_pcr);
/* Convert ts to PCRTIME */
res = gst_util_uint64_scale (GSTTIME_TO_PCRTIME (ts),
pcrtable->last_offset - pcrtable->first_offset,
pcrtable->last_pcr - pcrtable->first_pcr);
res += pcrtable->first_offset + priv->refoffset;
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->priv->refoffset = refoffset;
}
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