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ffmdec: limit the backward seek to the last resync position

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If resyncing leads to the same position as previously, it will again
lead to a resync attempt, resulting in an infinite loop.

Thus don't seek back beyond the last syncpoint.

Signed-off-by: Andreas Cadhalpun <Andreas.Cadhalpun@googlemail.com>
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
This commit is contained in:
Andreas Cadhalpun 2015-03-09 14:59:44 +01:00 committed by Michael Niedermayer
parent b4ec6afd3d
commit 6b8263b03a
1 changed files with 7 additions and 2 deletions
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9
libavformat/ffmdec.c
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@ -82,6 +82,7 @@ static int ffm_read_data(AVFormatContext *s,
FFMContext *ffm = s->priv_data; FFMContext *ffm = s->priv_data;
AVIOContext *pb = s->pb; AVIOContext *pb = s->pb;
int len, fill_size, size1, frame_offset, id; int len, fill_size, size1, frame_offset, id;
int64_t last_pos = -1;
size1 = size; size1 = size;
while (size > 0) { while (size > 0) {
@ -101,9 +102,11 @@ static int ffm_read_data(AVFormatContext *s,
avio_seek(pb, tell, SEEK_SET); avio_seek(pb, tell, SEEK_SET);
} }
id = avio_rb16(pb); /* PACKET_ID */ id = avio_rb16(pb); /* PACKET_ID */
if (id != PACKET_ID) if (id != PACKET_ID) {
if (ffm_resync(s, id) < 0) if (ffm_resync(s, id) < 0)
return -1; return -1;
last_pos = avio_tell(pb);
}
fill_size = avio_rb16(pb); fill_size = avio_rb16(pb);
ffm->dts = avio_rb64(pb); ffm->dts = avio_rb64(pb);
frame_offset = avio_rb16(pb); frame_offset = avio_rb16(pb);
@ -117,7 +120,9 @@ static int ffm_read_data(AVFormatContext *s,
if (!frame_offset) { if (!frame_offset) {
/* This packet has no frame headers in it */ /* This packet has no frame headers in it */
if (avio_tell(pb) >= ffm->packet_size * 3LL) { if (avio_tell(pb) >= ffm->packet_size * 3LL) {
avio_seek(pb, -ffm->packet_size * 2LL, SEEK_CUR); int64_t seekback = FFMIN(ffm->packet_size * 2LL, avio_tell(pb) - last_pos);
seekback = FFMAX(seekback, 0);
avio_seek(pb, -seekback, SEEK_CUR);
goto retry_read; goto retry_read;
} }
/* This is bad, we cannot find a valid frame header */ /* This is bad, we cannot find a valid frame header */