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avformat/subtitles: binary search seeking.

This commit is contained in:
Clément Bœsch 2013-09-08 12:36:57 +02:00
parent 1ca4bf930b
commit b1319e14e3
1 changed files with 37 additions and 15 deletions
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52
libavformat/subtitles.c
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@ -1,5 +1,5 @@
/*
* Copyright (c) 2012 Clément Bœsch
* Copyright (c) 2012-2013 Clément Bœsch <u pkh me>
*
* This file is part of FFmpeg.
*
@ -94,6 +94,28 @@ int ff_subtitles_queue_read_packet(FFDemuxSubtitlesQueue *q, AVPacket *pkt)
return 0;
}
static int search_sub_ts(const FFDemuxSubtitlesQueue *q, int64_t ts)
{
int s1 = 0, s2 = q->nb_subs - 1;
if (s2 < s1)
return AVERROR(ERANGE);
for (;;) {
int mid;
if (s1 == s2)
return s1;
if (s1 == s2 - 1)
return q->subs[s1].pts <= q->subs[s2].pts ? s1 : s2;
mid = (s1 + s2) / 2;
if (q->subs[mid].pts <= ts)
s1 = mid;
else
s2 = mid;
}
}
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)
{
@ -104,23 +126,23 @@ int ff_subtitles_queue_seek(FFDemuxSubtitlesQueue *q, AVFormatContext *s, int st
return AVERROR(ERANGE);
q->current_sub_idx = ts;
} else {
int i, idx = -1;
int64_t min_ts_diff = INT64_MAX;
int i, idx = search_sub_ts(q, ts);
int64_t ts_selected;
/* 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 ((stream_index == -1 || q->subs[i].stream_index == stream_index) &&
pts >= min_ts && pts <= max_ts && ts_diff < min_ts_diff) {
min_ts_diff = ts_diff;
idx = i;
}
}
if (idx < 0)
return AVERROR(ERANGE);
/* look back in the latest subtitles for overlapping subtitles */
return idx;
for (i = idx; i < q->nb_subs && q->subs[i].pts < min_ts; i++)
if (stream_index == -1 || q->subs[i].stream_index == stream_index)
idx = i;
for (i = idx; i > 0 && q->subs[i].pts > max_ts; i--)
if (stream_index == -1 || q->subs[i].stream_index == stream_index)
idx = i;
ts_selected = q->subs[idx].pts;
if (ts_selected < min_ts || ts_selected > max_ts)
return AVERROR(ERANGE);
/* look back in the latest subtitles for overlapping subtitles */
for (i = idx - 1; i >= 0; i--) {
int64_t pts = q->subs[i].pts;
if (q->subs[i].duration <= 0 ||