Re: [FFmpeg-devel] [PATCH] avfilter/formats: set audio fmt lists for vaf filters

[Michael Niedermayer <michael@niedermayer.cc>]

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On Thu, Dec 14, 2023 at 03:40:36PM +0100, Niklas Haas wrote:
> On Thu, 14 Dec 2023 15:39:11 +0100 Niklas Haas <ffmpeg@haasn.xyz> wrote:
> > From: Niklas Haas <git@haasn.dev>
> > 
> > Currently, the logic inside the FF_FILTER_FORMATS_QUERY_FUNC branch
> > prevents this code from running in the event that we have a filter with
> > a single video input and a single audio output, as the resulting audio
> > output link will not have its channel counts / samplerates correctly
> > initialized to their default values, possibly triggering a segfault
> > downstream.
> > 
> > An example of such a filter is vaf_spectrumsynth. Although this
> > particular filter already sets up the channel counts and samplerates as
> > part of the query function and therefore avoids triggering this bug, the
> > bug still exists in principle. (And importantly, sets a wrong precedent)
> > ---
> >  libavfilter/formats.c | 9 +++++----
> >  1 file changed, 5 insertions(+), 4 deletions(-)
> > 
> > diff --git a/libavfilter/formats.c b/libavfilter/formats.c
> > index d1c97daf64..114886aeb2 100644
> > --- a/libavfilter/formats.c
> > +++ b/libavfilter/formats.c
> > @@ -808,16 +808,17 @@ int ff_default_query_formats(AVFilterContext *ctx)
> >      /* Intended fallthrough */
> >      case FF_FILTER_FORMATS_PASSTHROUGH:
> >      case FF_FILTER_FORMATS_QUERY_FUNC:
> > -        type    = ctx->nb_inputs  ? ctx->inputs [0]->type :
> > -                  ctx->nb_outputs ? ctx->outputs[0]->type : AVMEDIA_TYPE_VIDEO;
> > -        formats = ff_all_formats(type);
> > +        type = AVMEDIA_TYPE_UNKNOWN;
> > +        formats = ff_all_formats(ctx->nb_inputs  ? ctx->inputs [0]->type :
> > +                                 ctx->nb_outputs ? ctx->outputs[0]->type :
> > +                                 AVMEDIA_TYPE_VIDEO);
> >          break;
> >      }
> >  
> >      ret = ff_set_common_formats(ctx, formats);
> >      if (ret < 0)
> >          return ret;
> > -    if (type == AVMEDIA_TYPE_AUDIO) {
> > +    if (type != AVMEDIA_TYPE_VIDEO) {
> >          ret = ff_set_common_all_channel_counts(ctx);
> >          if (ret < 0)
> >              return ret;
> > -- 
> > 2.43.0
> > 
> 
> This patch fixes the underlying issue (alongside the corresponding
> adjustment to the conditional from `type == AVMEDIA_TYPE_VIDEO` to `type
> != AVMEDIA_TYPE_AUDIO` in patch 03/15).

do you have some git branch i can test so i dont have to apply a patchset
with adjustments and hope i have the exact same code ?

thx

[...]
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Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

In fact, the RIAA has been known to suggest that students drop out
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settlements. -- The RIAA

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