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tsdemux: fix M2TS stream resync

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Sync byte scan is incorrect for M2TS streams because the timestamp 4
bytes were not included in the flush size. This can result in an
infinite loop.

Rework the scan code to be clearer and work in all cases.
This commit is contained in:
Arnaud Vrac 2013-05-27 22:22:32 +02:00 committed by Edward Hervey
parent 065d421d34
commit a5402d6eeb
1 changed files with 28 additions and 32 deletions
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50
gst/mpegtsdemux/mpegtspacketizer.c
View file

@ -2636,67 +2636,63 @@ mpegts_packetizer_next_packet (MpegTSPacketizer2 * packetizer,
MpegTSPacketizerPacket * packet)
{
MpegTSPacketizerPrivate *priv = packetizer->priv;
guint avail;
int i;
guint skip;
guint sync_offset;
if (G_UNLIKELY (!packetizer->know_packet_size)) {
if (!mpegts_try_discover_packet_size (packetizer))
return PACKET_NEED_MORE;
}
while ((avail = priv->available) >= packetizer->packet_size) {
while (priv->available >= packetizer->packet_size) {
if (priv->mapped == NULL) {
priv->mapped_size =
priv->available - (priv->available % packetizer->packet_size);
priv->mapped_size = priv->available;
priv->mapped =
(guint8 *) gst_adapter_map (packetizer->adapter, priv->mapped_size);
priv->offset = 0;
}
packet->data_start = priv->mapped + priv->offset;
/* M2TS packets don't start with the sync byte, all other variants do */
sync_offset = priv->offset;
if (packetizer->packet_size == MPEGTS_M2TS_PACKETSIZE)
packet->data_start += 4;
sync_offset += 4;
/* 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 */
/* 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 += packetizer->packet_size;
GST_MEMDUMP ("data_start", packet->data_start, 16);
packet->origts = priv->last_in_time;
/* Check sync byte */
if (G_LIKELY (packet->data_start[0] == 0x47))
goto got_valid_packet;
}
GST_LOG ("Lost sync %d", packetizer->packet_size);
/* Find the 0x47 in the buffer */
for (i = 0; i < packetizer->packet_size; i++)
if (packet->data_start[i] == 0x47)
for (; sync_offset < priv->mapped_size; sync_offset++)
if (priv->mapped[sync_offset] == 0x47)
break;
if (packetizer->packet_size == MPEGTS_M2TS_PACKETSIZE) {
if (i >= 4)
i -= 4;
else
i += 188;
}
GST_DEBUG ("Flushing %d bytes out", i);
/* gst_adapter_flush (packetizer->adapter, i); */
/* Pop out the remaining data... */
priv->offset += i;
priv->available -= i;
skip = sync_offset - priv->offset;
if (packetizer->packet_size == MPEGTS_M2TS_PACKETSIZE)
skip -= 4;
priv->available -= skip;
priv->offset += skip;
packetizer->offset += skip;
if (G_UNLIKELY (priv->available < packetizer->packet_size)) {
GST_DEBUG ("Flushing %d bytes out", priv->offset);
gst_adapter_flush (packetizer->adapter, priv->offset);
priv->mapped = NULL;
}
continue;
}
return PACKET_NEED_MORE;