Message ID | 20230822120304.396910-1-ulrik.mikaelsson@gmail.com |
---|---|
State | New |
Headers | show |
Series | [FFmpeg-devel] avformat/mp3dec:Subtract known padding from duration | expand |
Context | Check | Description |
---|---|---|
yinshiyou/commit_msg_loongarch64 | warning | The first line of the commit message must start with a context terminated by a colon and a space, for example "lavu/opt: " or "doc: ". |
andriy/commit_msg_x86 | warning | The first line of the commit message must start with a context terminated by a colon and a space, for example "lavu/opt: " or "doc: ". |
andriy/make_x86 | success | Make finished |
andriy/make_fate_x86 | fail | Make fate failed |
tis 2023-08-22 klockan 14:03 +0200 skrev Ulrik Mikaelsson: > When an Info-tag is present, marking initial and trailing samples as > padding, those samples should not be included in the calculation of > track > duration. > > This solves a surprising user experience where converting a WAV->MP3- > >WAV, > ffprobe will show the duration of the mp3 as slightly longer than > both the > input and the output. I've had similar issues with burning gapless CDs. Hopefully this fixes some downstream projects. > --- > libavformat/mp3dec.c | 3 ++- > 1 file changed, 2 insertions(+), 1 deletion(-) > > diff --git a/libavformat/mp3dec.c b/libavformat/mp3dec.c > index 05c13228bc..c8c3b298ab 100644 > --- a/libavformat/mp3dec.c > +++ b/libavformat/mp3dec.c > @@ -350,7 +350,8 @@ static int mp3_parse_vbr_tags(AVFormatContext *s, > AVStream *st, int64_t base) > avio_seek(s->pb, base + vbrtag_size, SEEK_SET); > > if (mp3->frames) > - st->duration = av_rescale_q(mp3->frames, (AVRational){spf, > c.sample_rate}, > + st->duration = av_rescale_q((mp3->frames * spf) - mp3- > >start_pad - mp3->end_pad, This can overflow. Casting to int64_t before multiplying should be enough to fix it. /Tomas
> > --- > > libavformat/mp3dec.c | 3 ++- > > 1 file changed, 2 insertions(+), 1 deletion(-) > > > > diff --git a/libavformat/mp3dec.c b/libavformat/mp3dec.c > > index 05c13228bc..c8c3b298ab 100644 > > --- a/libavformat/mp3dec.c > > +++ b/libavformat/mp3dec.c > > @@ -350,7 +350,8 @@ static int mp3_parse_vbr_tags(AVFormatContext *s, > > AVStream *st, int64_t base) > > avio_seek(s->pb, base + vbrtag_size, SEEK_SET); > > > > if (mp3->frames) > > - st->duration = av_rescale_q(mp3->frames, (AVRational){spf, > > c.sample_rate}, > > + st->duration = av_rescale_q((mp3->frames * spf) - mp3- > > >start_pad - mp3->end_pad, > > This can overflow. Casting to int64_t before multiplying should be > enough to fix it. Good catch! I also noticed a fate-test failed (due to it including padding-samples in the reference output for duration), and a formatting error in the patch itself. Will fix and resubmit. Den ons 23 aug. 2023 kl 11:18 skrev Tomas Härdin <git@haerdin.se>: > > tis 2023-08-22 klockan 14:03 +0200 skrev Ulrik Mikaelsson: > > When an Info-tag is present, marking initial and trailing samples as > > padding, those samples should not be included in the calculation of > > track > > duration. > > > > This solves a surprising user experience where converting a WAV->MP3- > > >WAV, > > ffprobe will show the duration of the mp3 as slightly longer than > > both the > > input and the output. > > I've had similar issues with burning gapless CDs. Hopefully this fixes > some downstream projects. > > > --- > > libavformat/mp3dec.c | 3 ++- > > 1 file changed, 2 insertions(+), 1 deletion(-) > > > > diff --git a/libavformat/mp3dec.c b/libavformat/mp3dec.c > > index 05c13228bc..c8c3b298ab 100644 > > --- a/libavformat/mp3dec.c > > +++ b/libavformat/mp3dec.c > > @@ -350,7 +350,8 @@ static int mp3_parse_vbr_tags(AVFormatContext *s, > > AVStream *st, int64_t base) > > avio_seek(s->pb, base + vbrtag_size, SEEK_SET); > > > > if (mp3->frames) > > - st->duration = av_rescale_q(mp3->frames, (AVRational){spf, > > c.sample_rate}, > > + st->duration = av_rescale_q((mp3->frames * spf) - mp3- > > >start_pad - mp3->end_pad, > > This can overflow. Casting to int64_t before multiplying should be > enough to fix it. > > /Tomas > _______________________________________________ > ffmpeg-devel mailing list > ffmpeg-devel@ffmpeg.org > https://ffmpeg.org/mailman/listinfo/ffmpeg-devel > > To unsubscribe, visit link above, or email > ffmpeg-devel-request@ffmpeg.org with subject "unsubscribe".
diff --git a/libavformat/mp3dec.c b/libavformat/mp3dec.c index 05c13228bc..c8c3b298ab 100644 --- a/libavformat/mp3dec.c +++ b/libavformat/mp3dec.c @@ -350,7 +350,8 @@ static int mp3_parse_vbr_tags(AVFormatContext *s, AVStream *st, int64_t base) avio_seek(s->pb, base + vbrtag_size, SEEK_SET); if (mp3->frames) - st->duration = av_rescale_q(mp3->frames, (AVRational){spf, c.sample_rate}, + st->duration = av_rescale_q((mp3->frames * spf) - mp3->start_pad - mp3->end_pad, + (AVRational){1, c.sample_rate}, st->time_base); if (mp3->header_filesize && mp3->frames && !mp3->is_cbr) st->codecpar->bit_rate = av_rescale(mp3->header_filesize, 8 * c.sample_rate, mp3->frames * (int64_t)spf);