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authorAndy Wu <tsunghung@chromium.org>2015-08-31 17:08:30 -0700
committerwm4 <nfxjfg@googlemail.com>2015-09-05 18:32:58 +0200
commitc43bd08f8b043df7e18110e5344283c37b8380c1 (patch)
tree3aae7343d92bc2697b76e84dc3ab6174d2e0065d /libavformat/mp3dec.c
parent237cf3786ef7dea60818fc3bc464f72ed4b4d833 (diff)
downloadffmpeg-c43bd08f8b043df7e18110e5344283c37b8380c1.tar.gz
avformat/mp3dec: Make MP3 seek fast
When AVFMT_FLAG_FAST_SEEK is specified, make MP3 seek operation as fast as possible. When no "-usetoc" is specified, the default operation is using TOC if available; otherwise, uses linear interpolation. This is useful when seeking a large MP3 file with no TOC available. One example is Podcast, many MP3 files are large, but no CBR/VBR tags. Most of them are actually CBR. Even in VBR cases, this option sacrifices the accuracy of playback time in exchange for responsiveness.
Diffstat (limited to 'libavformat/mp3dec.c')
-rw-r--r--libavformat/mp3dec.c19
1 files changed, 13 insertions, 6 deletions
diff --git a/libavformat/mp3dec.c b/libavformat/mp3dec.c
index 007c6eaf8b..d3080d715c 100644
--- a/libavformat/mp3dec.c
+++ b/libavformat/mp3dec.c
@@ -342,7 +342,7 @@ static int mp3_read_header(AVFormatContext *s)
int i;
if (mp3->usetoc < 0)
- mp3->usetoc = (s->flags & AVFMT_FLAG_FAST_SEEK) ? 0 : 2;
+ mp3->usetoc = (s->flags & AVFMT_FLAG_FAST_SEEK) ? 1 : 2;
st = avformat_new_stream(s, NULL);
if (!st)
@@ -489,19 +489,26 @@ static int mp3_seek(AVFormatContext *s, int stream_index, int64_t timestamp,
AVStream *st = s->streams[0];
int64_t ret = av_index_search_timestamp(st, timestamp, flags);
int64_t best_pos;
+ int fast_seek = (s->flags & AVFMT_FLAG_FAST_SEEK) ? 1 : 0;
+ int64_t filesize = mp3->header_filesize;
if (mp3->usetoc == 2)
return -1; // generic index code
- if ( mp3->is_cbr
+ if (filesize <= 0) {
+ int64_t size = avio_size(s->pb);
+ if (size > 0 && size > s->internal->data_offset)
+ filesize = size - s->internal->data_offset;
+ }
+
+ if ( (mp3->is_cbr || fast_seek)
&& (mp3->usetoc == 0 || !mp3->xing_toc)
&& st->duration > 0
- && mp3->header_filesize > s->internal->data_offset
- && mp3->frames) {
+ && filesize > 0) {
ie = &ie1;
timestamp = av_clip64(timestamp, 0, st->duration);
ie->timestamp = timestamp;
- ie->pos = av_rescale(timestamp, mp3->header_filesize, st->duration) + s->internal->data_offset;
+ ie->pos = av_rescale(timestamp, filesize, st->duration) + s->internal->data_offset;
} else if (mp3->xing_toc) {
if (ret < 0)
return ret;
@@ -515,7 +522,7 @@ static int mp3_seek(AVFormatContext *s, int stream_index, int64_t timestamp,
if (best_pos < 0)
return best_pos;
- if (mp3->is_cbr && ie == &ie1) {
+ if (mp3->is_cbr && ie == &ie1 && mp3->frames) {
int frame_duration = av_rescale(st->duration, 1, mp3->frames);
ie1.timestamp = frame_duration * av_rescale(best_pos - s->internal->data_offset, mp3->frames, mp3->header_filesize);
}