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lavf/subtitles: add ff_subtitles_queue_seek().

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This function is almost identical to lavf/assdec:read_seek2(). It
performs a generic seek for text subtitles demuxers for the new seeking
API.

The only difference with assdec:read_seek2 is the ts_diff being
unsigned to avoid overflows.

The seek callback in the ASS demuxer will be removed when it is
redesigned to use FFDemuxSubtitlesQueue.
This commit is contained in:
Clément Bœsch 2012-11-23 21:40:46 +01:00
parent b684f744ac
commit ff3624b1ad
2 changed files with 45 additions and 0 deletions
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38
libavformat/subtitles.c
View File

@ -91,6 +91,44 @@ int ff_subtitles_queue_read_packet(FFDemuxSubtitlesQueue *q, AVPacket *pkt)
return 0;
}
int ff_subtitles_queue_seek(FFDemuxSubtitlesQueue *q, AVFormatContext *s, int stream_index,
int64_t min_ts, int64_t ts, int64_t max_ts, int flags)
{
if (flags & AVSEEK_FLAG_BYTE) {
return AVERROR(ENOSYS);
} else if (flags & AVSEEK_FLAG_FRAME) {
if (ts < 0 || ts >= q->nb_subs)
return AVERROR(ERANGE);
q->current_sub_idx = ts;
} else {
int i, idx = -1;
int64_t min_ts_diff = INT64_MAX;
if (stream_index == -1) {
AVRational time_base = s->streams[0]->time_base;
ts = av_rescale_q(ts, AV_TIME_BASE_Q, time_base);
min_ts = av_rescale_rnd(min_ts, time_base.den,
time_base.num * (int64_t)AV_TIME_BASE,
AV_ROUND_UP);
max_ts = av_rescale_rnd(max_ts, time_base.den,
time_base.num * (int64_t)AV_TIME_BASE,
AV_ROUND_DOWN);
}
/* TODO: q->subs[] is sorted by pts so we could do a binary search */
for (i = 0; i < q->nb_subs; i++) {
int64_t pts = q->subs[i].pts;
uint64_t ts_diff = FFABS(pts - ts);
if (pts >= min_ts && pts <= max_ts && ts_diff < min_ts_diff) {
min_ts_diff = ts_diff;
idx = i;
}
}
if (idx < 0)
return AVERROR(ERANGE);
q->current_sub_idx = idx;
}
return 0;
}
void ff_subtitles_queue_clean(FFDemuxSubtitlesQueue *q)
{
int i;

7
libavformat/subtitles.h
View File

@ -54,6 +54,13 @@ void ff_subtitles_queue_finalize(FFDemuxSubtitlesQueue *q);
*/
int ff_subtitles_queue_read_packet(FFDemuxSubtitlesQueue *q, AVPacket *pkt);
/**
* Update current_sub_idx to emulate a seek. Except the first parameter, it
* matches AVInputFormat->read_seek2 prototypes.
*/
int ff_subtitles_queue_seek(FFDemuxSubtitlesQueue *q, AVFormatContext *s, int stream_index,
int64_t min_ts, int64_t ts, int64_t max_ts, int flags);
/**
* Remove and destroy all the subtitles packets.
*/