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hlsdemux: Do some reading and dumping of PCRs

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Read PCRs out of the MPEG-TS stream in a basic way
and (for now) just log them
This commit is contained in:
Jan Schmidt 2016-02-24 16:57:16 +11:00
parent d9daa5d0b3
commit 8cf50dbc44
4 changed files with 281 additions and 7 deletions
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1
ext/hls/Makefile.am
View file

@ -4,6 +4,7 @@ plugin_LTLIBRARIES = libgsthls.la
libgsthls_la_SOURCES = \
m3u8.c \
gsthlsdemux.c \
gsthlsdemux-util.c \
gsthlsplugin.c \
gsthlssink.c \
gstm3u8playlist.c

212
ext/hls/gsthlsdemux-util.c Normal file
View file

@ -0,0 +1,212 @@
#include <gst/gst.h>
#include <string.h>
#include "gsthlsdemux.h"
GST_DEBUG_CATEGORY_EXTERN (gst_hls_demux_debug);
#define GST_CAT_DEFAULT gst_hls_demux_debug
/* Check for sync byte, error_indicator == 0 and packet has payload.
* Adaptation control field (data[3] & 0x30) may be zero for TS packets with
* null PIDs. Still, these streams are valid TS streams (for null packets,
* AFC is supposed to be 0x1, but the spec also says decoders should just
* discard any packets with AFC = 0x00) */
#define IS_MPEGTS_HEADER(data) (data[0] == 0x47 && \
(data[1] & 0x80) == 0x00 && \
((data[3] & 0x30) != 0x00 || \
((data[3] & 0x30) == 0x00 && (data[1] & 0x1f) == 0x1f && (data[2] & 0xff) == 0xff)))
static gboolean
have_ts_sync (const guint8 * data, guint size, guint packet_size, guint num)
{
while (num-- > 0) {
if (size < packet_size)
return FALSE;
if (!IS_MPEGTS_HEADER (data))
return FALSE;
data += packet_size;
size -= packet_size;
}
return TRUE;
}
static gint
find_offset (GstHLSTSReader * r, const guint8 * data, guint size)
{
guint sync_points = CLAMP (size / 188, 25, 100);
guint off;
const gint packet_size = 188;
/* FIXME: check 192 as well, and maybe also 204, 208 */
for (off = 0; off < MIN (size, packet_size); ++off) {
if (have_ts_sync (data + off, size - off, packet_size, sync_points)) {
r->packet_size = packet_size;
return off;
}
}
return -1;
}
static gboolean
handle_pcr (GstHLSTSReader * r, const guint8 * data, guint size)
{
const guint8 *p = data;
guint32 hdr = GST_READ_UINT32_BE (p);
guint af_len, flags;
guint64 pcr_base, pcr_ext, pcr, ts;
data = p + 4;
if ((hdr & 0x00000020) == 0) /* has_adaptation_field */
return FALSE;
af_len = p[4]; /* adaptation_field_len */
++data;
if (af_len < (1 + 6) || af_len > r->packet_size - (4 + 1))
return FALSE;
flags = data[0];
/* Does the packet have a PCR? */
if ((flags & 0x10) == 0)
return FALSE;
++data;
--af_len;
pcr_base = (GST_READ_UINT64_BE (data) >> 16) >> (6 + 9);
pcr_ext = (GST_READ_UINT64_BE (data) >> 16) & 0x1ff;
pcr = pcr_base * 300 + pcr_ext;
#define PCRTIME_TO_GSTTIME(t) (((t) * (guint64)1000) / 27)
ts = PCRTIME_TO_GSTTIME (pcr);
GST_LOG ("have PCR! %" G_GUINT64_FORMAT "\t%" GST_TIME_FORMAT,
pcr, GST_TIME_ARGS (ts));
if (r->first_pcr == GST_CLOCK_TIME_NONE)
r->first_pcr = ts;
r->last_pcr = ts;
return TRUE;
}
static gboolean
handle_pmt (GstHLSTSReader * r, const guint8 * data, guint size)
{
const guint8 *p = data;
guint32 hdr = GST_READ_UINT32_BE (p);
guint slen, pcr_pid;
data = p + 4;
if ((hdr & 0x00000020) != 0) /* has_adaptation_field */
data += 1 + p[4]; /* adaptation_field_len */
data += 1 + data[0]; /* pointer_field */
if (data[0] != 0x02) /* table_id */
return FALSE;
//gst_util_dump_mem (data, 8);
/* we assume the entire PMT fits into a single packet and this is it */
if (data[6] != 0 || data[6] != data[7])
return FALSE;
slen = GST_READ_UINT16_BE (data + 1) & 0x0FFF;
if (slen > (gsize) (p + r->packet_size - (data + 1 + 2)) || slen < 5 + 2 + 4)
return FALSE;
data += 3 + 5;
slen -= 5; /* bytes after section_length field itself */
slen -= 4; /* crc at end */
pcr_pid = GST_READ_UINT16_BE (data) & 0x1fff;
if (pcr_pid != 0x1fff) {
GST_DEBUG ("pcr_pid now: %04x", pcr_pid);
r->pcr_pid = pcr_pid;
return TRUE;
}
return FALSE;
}
static gboolean
handle_pat (GstHLSTSReader * r, const guint8 * data, guint size)
{
const guint8 *p = data;
guint32 hdr = GST_READ_UINT32_BE (p);
guint slen;
data = p + 4;
if ((hdr & 0x00000020) != 0) /* has_adaptation_field */
data += 1 + p[4]; /* adaptation_field_len */
data += 1 + data[0]; /* pointer_field */
if (data[0] != 0) /* table_id */
return FALSE;
/* we assume the entire PAT fits into a single packet and this is it */
if (data[6] != 0 || data[6] != data[7])
return FALSE;
slen = GST_READ_UINT16_BE (data + 1) & 0x0FFF;
if (slen > (gsize) (p + r->packet_size - (data + 1 + 2)) || slen < 5 + 4 + 4)
return FALSE;
data += 3 + 5;
slen -= 5; /* bytes after section_length field itself */
slen -= 4; /* crc at end */
while (slen >= 4) {
guint program_num = GST_READ_UINT16_BE (data);
guint val = GST_READ_UINT16_BE (data + 2) & 0x1fff;
if (program_num != 0) {
GST_DEBUG (" program %04x: pmt_pid : %04x\n", program_num, val);
r->pmt_pid = val;
return TRUE;
}
data += 4;
slen -= 4;
}
return FALSE;
}
void
gst_hlsdemux_tsreader_init (GstHLSTSReader * r)
{
r->packet_size = 188;
r->pmt_pid = r->pcr_pid = -1;
r->first_pcr = GST_CLOCK_TIME_NONE;
r->last_pcr = GST_CLOCK_TIME_NONE;
}
gboolean
gst_hlsdemux_tsreader_find_pcrs (GstHLSTSReader * r,
const guint8 * data, guint size, GstClockTime * first_pcr,
GstClockTime * last_pcr)
{
gint offset;
const guint8 *p;
*first_pcr = *last_pcr = GST_CLOCK_TIME_NONE;
offset = find_offset (r, data, size);
if (offset < 0)
return FALSE;
GST_LOG ("TS packet start offset: %d", offset);
data += offset;
size -= offset;
for (p = data; size >= r->packet_size;
p += r->packet_size, size -= r->packet_size) {
guint32 hdr = GST_READ_UINT32_BE (p);
/* sync byte (0x47), error indicator (TEI) not set, PID 0, has_payload */
if ((hdr & 0xFF9FFF10) == 0x47000010) {
GST_LOG ("Found packet for PID 0000 (PAT)");
handle_pat (r, p, size);
}
/* sync byte (0x47), error indicator (TEI) not set, has_payload, PID = PMT_pid */
else if ((hdr & 0xFF800010) == 0x47000010
&& ((hdr >> 8) & 0x1fff) == r->pmt_pid) {
GST_LOG ("Found packet for PID %04x (PMT)", r->pmt_pid);
handle_pmt (r, p, size);
}
/* sync byte (0x47), error indicator (TEI) not set, has_payload */
else if ((hdr & 0xFF800010) == 0x47000010
&& ((hdr >> 8) & 0x1fff) == r->pcr_pid) {
GST_LOG ("Found packet for PID %04x (PCR)", r->pcr_pid);
handle_pcr (r, p, size);
}
}
*first_pcr = r->first_pcr;
*last_pcr = r->last_pcr;
/* Return TRUE if this piece was big enough to get a PCR from */
return (r->first_pcr != GST_CLOCK_TIME_NONE);
}

50
ext/hls/gsthlsdemux.c
View file

@ -55,7 +55,7 @@ static GstStaticPadTemplate sinktemplate = GST_STATIC_PAD_TEMPLATE ("sink",
GST_PAD_ALWAYS,
GST_STATIC_CAPS ("application/x-hls"));
GST_DEBUG_CATEGORY_STATIC (gst_hls_demux_debug);
GST_DEBUG_CATEGORY (gst_hls_demux_debug);
#define GST_CAT_DEFAULT gst_hls_demux_debug
#define GST_M3U8_CLIENT_LOCK(l) /* FIXME */
@ -248,6 +248,7 @@ gst_hls_demux_stream_clear_pending_data (GstHLSDemuxStream * hls_stream)
gst_adapter_clear (hls_stream->pending_encrypted_data);
gst_buffer_replace (&hls_stream->pending_decrypted_buffer, NULL);
gst_buffer_replace (&hls_stream->pending_typefind_buffer, NULL);
gst_buffer_replace (&hls_stream->pending_pcr_buffer, NULL);
hls_stream->current_offset = -1;
gst_hls_demux_stream_decrypt_end (hls_stream);
}
@ -695,6 +696,9 @@ gst_hls_demux_start_fragment (GstAdaptiveDemux * demux,
gst_hls_demux_stream_clear_pending_data (hls_stream);
/* Init the MPEG-TS reader for this fragment */
gst_hlsdemux_tsreader_init (&hls_stream->tsreader);
/* If no decryption is needed, there's nothing to be done here */
if (hls_stream->current_key == NULL)
return TRUE;
@ -727,13 +731,16 @@ gst_hls_demux_handle_buffer (GstAdaptiveDemux * demux,
{
GstHLSDemuxStream *hls_stream = GST_HLS_DEMUX_STREAM_CAST (stream); // FIXME: pass HlsStream into function
GstHLSDemux *hlsdemux = GST_HLS_DEMUX_CAST (demux);
GstMapInfo info;
GstClockTime first_pcr, last_pcr;
if (buffer == NULL)
return GST_FLOW_OK;
gst_buffer_map (buffer, &info, GST_MAP_READ);
if (G_UNLIKELY (hls_stream->do_typefind)) {
GstCaps *caps = NULL;
GstMapInfo info;
guint buffer_size;
GstTypeFindProbability prob = GST_TYPE_FIND_NONE;
@ -751,9 +758,11 @@ gst_hls_demux_handle_buffer (GstAdaptiveDemux * demux,
gst_type_find_helper_for_data (GST_OBJECT_CAST (hlsdemux), info.data,
info.size, &prob);
}
gst_buffer_unmap (buffer, &info);
if (G_UNLIKELY (!caps)) {
/* Won't need this mapping any more all paths return inside this if() */
gst_buffer_unmap (buffer, &info);
/* Only fail typefinding if we already a good amount of data
* and we still don't know the type */
if (buffer_size > (2 * 1024 * 1024) || at_eos) {
@ -776,6 +785,25 @@ gst_hls_demux_handle_buffer (GstAdaptiveDemux * demux,
}
g_assert (hls_stream->pending_typefind_buffer == NULL);
// Accumulate this buffer
if (hls_stream->pending_pcr_buffer) {
gst_buffer_unmap (buffer, &info);
buffer = gst_buffer_append (hls_stream->pending_pcr_buffer, buffer);
hls_stream->pending_pcr_buffer = NULL;
gst_buffer_map (buffer, &info, GST_MAP_READ);
}
if (!gst_hlsdemux_tsreader_find_pcrs (&hls_stream->tsreader, info.data,
info.size, &first_pcr, &last_pcr)
&& !at_eos) {
gst_buffer_unmap (buffer, &info);
// Store this buffer for later
hls_stream->pending_pcr_buffer = buffer;
return GST_FLOW_OK;
}
gst_buffer_unmap (buffer, &info);
if (buffer) {
buffer = gst_buffer_make_writable (buffer);
GST_BUFFER_OFFSET (buffer) = hls_stream->current_offset;
@ -818,6 +846,21 @@ gst_hls_demux_finish_fragment (GstAdaptiveDemux * demux,
hls_stream->pending_decrypted_buffer = NULL;
}
}
if (ret == GST_FLOW_OK || ret == GST_FLOW_NOT_LINKED) {
if (hls_stream->pending_pcr_buffer) {
GstBuffer *buf = hls_stream->pending_pcr_buffer;
hls_stream->pending_pcr_buffer = NULL;
ret = gst_hls_demux_handle_buffer (demux, stream, buf, TRUE);
}
GST_LOG_OBJECT (stream,
"Fragment PCRs were %" GST_TIME_FORMAT " to %" GST_TIME_FORMAT,
GST_TIME_ARGS (hls_stream->tsreader.first_pcr),
GST_TIME_ARGS (hls_stream->tsreader.last_pcr));
}
gst_hls_demux_stream_clear_pending_data (hls_stream);
if (ret == GST_FLOW_OK || ret == GST_FLOW_NOT_LINKED)
@ -888,6 +931,7 @@ gst_hls_demux_stream_free (GstAdaptiveDemuxStream * stream)
gst_buffer_replace (&hls_stream->pending_decrypted_buffer, NULL);
gst_buffer_replace (&hls_stream->pending_typefind_buffer, NULL);
gst_buffer_replace (&hls_stream->pending_pcr_buffer, NULL);
if (hls_stream->current_key) {
g_free (hls_stream->current_key);

25
ext/hls/gsthlsdemux.h
View file

@ -58,9 +58,20 @@ G_BEGIN_DECLS
typedef struct _GstHLSDemux GstHLSDemux;
typedef struct _GstHLSDemuxClass GstHLSDemuxClass;
typedef struct _GstHLSDemuxStream GstHLSDemuxStream;
typedef struct _GstHLSTSReader GstHLSTSReader;
#define GST_HLS_DEMUX_STREAM_CAST(stream) ((GstHLSDemuxStream *)(stream))
struct _GstHLSTSReader
{
gint packet_size;
gint pmt_pid;
gint pcr_pid;
GstClockTime last_pcr;
GstClockTime first_pcr;
};
struct _GstHLSDemuxStream
{
GstAdaptiveDemux adaptive_demux_stream;
@ -89,10 +100,12 @@ struct _GstHLSDemuxStream
gchar *current_key;
guint8 *current_iv;
GstBuffer *pending_buffer; /* decryption scenario:
* the last buffer can only be pushed when
* resized, so need to store and wait for
* EOS to know it is the last */
/* Accumulator for reading PAT/PMT/PCR from
* the stream so we can set timestamps/segments
* and switch cleanly */
GstBuffer *pending_pcr_buffer;
GstHLSTSReader tsreader;
};
typedef struct {
@ -126,6 +139,10 @@ struct _GstHLSDemuxClass
GstAdaptiveDemuxClass parent_class;
};
void gst_hlsdemux_tsreader_init (GstHLSTSReader *r);
gboolean gst_hlsdemux_tsreader_find_pcrs (GstHLSTSReader *r, const guint8 * data, guint size,
GstClockTime *first_pcr, GstClockTime *last_pcr);
GType gst_hls_demux_get_type (void);
G_END_DECLS