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Parse 'cslg' atom to retrieve dts shift when 'ctts' duration is negative.

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We have now dts <= pts, note that for some B frames dts+1 == pts can happen
if a crappy timebase is used instead of correct /1001.

Originally committed as revision 18810 to svn://svn.ffmpeg.org/ffmpeg/trunk
This commit is contained in:
Baptiste Coudurier 2009-05-13 07:55:03 +00:00
parent ec21c21563
commit 4b29ed399f
2 changed files with 32 additions and 6 deletions
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3
libavformat/isom.h
View file

@ -115,9 +115,10 @@ typedef struct MOVStreamContext {
unsigned drefs_count; unsigned drefs_count;
MOVDref *drefs; MOVDref *drefs;
int dref_id; int dref_id;
int wrong_dts; ///< dts are wrong due to negative ctts int wrong_dts; ///< dts are wrong due to huge ctts offset (iMovie files)
int width; ///< tkhd width int width; ///< tkhd width
int height; ///< tkhd height int height; ///< tkhd height
int dts_shift; ///< dts shift when ctts is negative
} MOVStreamContext; } MOVStreamContext;
typedef struct MOVContext { typedef struct MOVContext {

35
libavformat/mov.c
View file

@ -1236,6 +1236,31 @@ static int mov_read_stts(MOVContext *c, ByteIOContext *pb, MOVAtom atom)
return 0; return 0;
} }
static int mov_read_cslg(MOVContext *c, ByteIOContext *pb, MOVAtom atom)
{
AVStream *st;
MOVStreamContext *sc;
if (c->fc->nb_streams < 1) // will happen with jp2 files
return 0;
st = c->fc->streams[c->fc->nb_streams-1];
sc = st->priv_data;
get_be32(pb); // version + flags
sc->dts_shift = get_be32(pb);
dprintf(c->fc, "dts shift %d\n", sc->dts_shift);
sc->time_rate= av_gcd(sc->time_rate, FFABS(sc->dts_shift));
get_be32(pb); // least dts to pts delta
get_be32(pb); // greatest dts to pts delta
get_be32(pb); // pts start
get_be32(pb); // pts end
return 0;
}
static int mov_read_ctts(MOVContext *c, ByteIOContext *pb, MOVAtom atom) static int mov_read_ctts(MOVContext *c, ByteIOContext *pb, MOVAtom atom)
{ {
AVStream *st = c->fc->streams[c->fc->nb_streams-1]; AVStream *st = c->fc->streams[c->fc->nb_streams-1];
@ -1259,10 +1284,6 @@ static int mov_read_ctts(MOVContext *c, ByteIOContext *pb, MOVAtom atom)
int count =get_be32(pb); int count =get_be32(pb);
int duration =get_be32(pb); int duration =get_be32(pb);
if (duration < 0) {
sc->wrong_dts = 1;
st->codec->has_b_frames = 1;
}
sc->ctts_data[i].count = count; sc->ctts_data[i].count = count;
sc->ctts_data[i].duration= duration; sc->ctts_data[i].duration= duration;
@ -1303,6 +1324,9 @@ static void mov_build_index(MOVContext *mov, AVStream *st)
unsigned int distance = 0; unsigned int distance = 0;
int key_off = sc->keyframes && sc->keyframes[0] == 1; int key_off = sc->keyframes && sc->keyframes[0] == 1;
sc->dts_shift /= sc->time_rate;
current_dts -= sc->dts_shift;
st->nb_frames = sc->sample_count; st->nb_frames = sc->sample_count;
for (i = 0; i < sc->chunk_count; i++) { for (i = 0; i < sc->chunk_count; i++) {
current_offset = sc->chunk_offsets[i]; current_offset = sc->chunk_offsets[i];
@ -1809,6 +1833,7 @@ static int mov_read_elst(MOVContext *c, ByteIOContext *pb, MOVAtom atom)
static const MOVParseTableEntry mov_default_parse_table[] = { static const MOVParseTableEntry mov_default_parse_table[] = {
{ MKTAG('a','v','s','s'), mov_read_extradata }, { MKTAG('a','v','s','s'), mov_read_extradata },
{ MKTAG('c','o','6','4'), mov_read_stco }, { MKTAG('c','o','6','4'), mov_read_stco },
{ MKTAG('c','s','l','g'), mov_read_cslg },
{ MKTAG('c','t','t','s'), mov_read_ctts }, /* composition time to sample */ { MKTAG('c','t','t','s'), mov_read_ctts }, /* composition time to sample */
{ MKTAG('d','i','n','f'), mov_read_default }, { MKTAG('d','i','n','f'), mov_read_default },
{ MKTAG('d','r','e','f'), mov_read_dref }, { MKTAG('d','r','e','f'), mov_read_dref },
@ -1988,7 +2013,7 @@ static int mov_read_packet(AVFormatContext *s, AVPacket *pkt)
pkt->dts = sample->timestamp; pkt->dts = sample->timestamp;
if (sc->ctts_data) { if (sc->ctts_data) {
assert(sc->ctts_data[sc->ctts_index].duration % sc->time_rate == 0); assert(sc->ctts_data[sc->ctts_index].duration % sc->time_rate == 0);
pkt->pts = pkt->dts + sc->ctts_data[sc->ctts_index].duration / sc->time_rate; pkt->pts = pkt->dts + sc->dts_shift + sc->ctts_data[sc->ctts_index].duration / sc->time_rate;
/* update ctts context */ /* update ctts context */
sc->ctts_sample++; sc->ctts_sample++;
if (sc->ctts_index < sc->ctts_count && if (sc->ctts_index < sc->ctts_count &&