[FFmpeg-devel] [PATCH v1] avformat/utils: Fixes misdetection of zYLx.wav

[Carl Eugen Hoyos]

Am Mi., 6. Nov. 2019 um 12:21 Uhr schrieb Limin Wang <lance.lmwang at gmail.com>:
>
> On Wed, Nov 06, 2019 at 11:18:10AM +0100, Carl Eugen Hoyos wrote:
> > Am Mi., 6. Nov. 2019 um 10:01 Uhr schrieb <lance.lmwang at gmail.com>:
> > >
> > > From: Limin Wang <lance.lmwang at gmail.com>
> > >
> > > Signed-off-by: Limin Wang <lance.lmwang at gmail.com>
> > > ---
> > >  libavformat/utils.c | 3 +--
> > >  1 file changed, 1 insertion(+), 2 deletions(-)
> > >
> > > diff --git a/libavformat/utils.c b/libavformat/utils.c
> > > index 8196442dd1..8381498e2b 100644
> > > --- a/libavformat/utils.c
> > > +++ b/libavformat/utils.c
> > > @@ -367,8 +367,7 @@ static int set_codec_from_probe_data(AVFormatContext *s, AVStream *st,
> > >                 fmt->name, score);
> > >          for (i = 0; fmt_id_type[i].name; i++) {
> > >              if (!strcmp(fmt->name, fmt_id_type[i].name)) {
> > > -                if (fmt_id_type[i].type != AVMEDIA_TYPE_AUDIO &&
> > > -                    st->codecpar->sample_rate)
> > > +                if (st->codecpar->sample_rate)
> > >                      continue;
> >
> > I believe the correct fix is to change the mp3 probe function so that it
> > does not return a score of 51 for the pcm pattern of ff ff e8 ff ff ff e8 ff...
>
> It has been detected as pcm

There is no pcm detection in FFmpeg (it is hard iiuc), and the content
does not get detected as pcm but mp3 / mp1.

> and have get the valid audio sample rate, why we detect it
> again here?

How else can you rule out dca audio?

> I have run fate testing with the patch and haven't find any broken condition.

fate cannot test for all possible code paths.

Carl Eugen