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avformat/mp3dec: Improve seeking frame sync code

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Fixes Ticket3884

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
(cherry picked from commit 1b5ccae0f2045ac86bc9e1257cec1b3fba81315f)
This commit is contained in:
Michael Niedermayer 2014-09-07 21:44:19 +02:00 committed by Carl Eugen Hoyos
parent 193b949f71
commit 19ccc06d8b
1 changed files with 19 additions and 8 deletions
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27
libavformat/mp3dec.c
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@ -398,6 +398,8 @@ static int mp3_seek(AVFormatContext *s, int stream_index, int64_t timestamp,
int64_t ret = av_index_search_timestamp(st, timestamp, flags);
int i, j;
int dir = (flags&AVSEEK_FLAG_BACKWARD) ? -1 : 1;
int64_t best_pos;
int best_score;
if (mp3->is_cbr && st->duration > 0 && mp3->header_filesize > s->data_offset) {
int64_t filesize = avio_size(s->pb);
@ -421,28 +423,37 @@ static int mp3_seek(AVFormatContext *s, int stream_index, int64_t timestamp,
return -1;
}
if (dir < 0)
avio_seek(s->pb, FFMAX(ie->pos - 4096, 0), SEEK_SET);
avio_seek(s->pb, FFMAX(ie->pos - 4096, 0), SEEK_SET);
ret = avio_seek(s->pb, ie->pos, SEEK_SET);
if (ret < 0)
return ret;
#define MIN_VALID 3
best_pos = ie->pos;
best_score = 999;
for(i=0; i<4096; i++) {
int64_t pos = ie->pos + i*dir;
int64_t pos = ie->pos + (dir > 0 ? i - 1024 : -i);
int64_t candidate = -1;
int score = 999;
for(j=0; j<MIN_VALID; j++) {
ret = check(s, pos);
if(ret < 0)
break;
if ((ie->pos - pos)*dir <= 0 && abs(MIN_VALID/2-j) < score) {
candidate = pos;
score = abs(MIN_VALID/2-j);
}
pos += ret;
}
if(j==MIN_VALID)
break;
if (best_score > score && j == MIN_VALID) {
best_pos = candidate;
best_score = score;
if(score == 0)
break;
}
}
if(j!=MIN_VALID)
i=0;
ret = avio_seek(s->pb, ie->pos + i*dir, SEEK_SET);
ret = avio_seek(s->pb, best_pos, SEEK_SET);
if (ret < 0)
return ret;
ff_update_cur_dts(s, st, ie->timestamp);