[FFmpeg-devel] [PATCH v4 1/1] avutils/hwcontext: When deriving a hwdevice, search for existing device in both directions

[Anton Khirnov]

Quoting Soft Works (2021-11-25 18:02:54)
> 
> 
> > -----Original Message-----
> > From: ffmpeg-devel <ffmpeg-devel-bounces at ffmpeg.org> On Behalf Of Anton
> > Khirnov
> > Sent: Thursday, November 25, 2021 5:40 PM
> > To: ffmpeg-devel at ffmpeg.org
> > Subject: Re: [FFmpeg-devel] [PATCH v4 1/1] avutils/hwcontext: When deriving a
> > hwdevice, search for existing device in both directions
> > 
> > Quoting Soft Works (2021-11-25 03:41:32)
> > > @@ -687,6 +720,11 @@ int av_hwdevice_ctx_create_derived_opts(AVBufferRef
> > **dst_ref_ptr,
> > >                      ret = AVERROR(ENOMEM);
> > >                      goto fail;
> > >                  }
> > > +                tmp_ctx->internal->derived_devices[type] =
> > av_buffer_ref(dst_ref);
> > > +                if (!tmp_ctx->internal->derived_devices[type]) {
> > > +                    ret = AVERROR(ENOMEM);
> > > +                    goto fail;
> > > +                }
> > 
> > This means that once you derive a device of a certain type, you can
> > never truly close it without also killing the parent device. That
> > strikes me as
> > - potentially troublesome
> > - a behavior change
> > 
> > Also, I don't see it as completely obvious that all derivations should
> > always return the same child instance.
> 
> 
> It creates the behavior that everybody wants and expects who is working 
> with HW devices derivation.

What qualifies you to speak for "everybody"? I would expect to hear some
practical arguments for such a strong claim.

-- 
Anton Khirnov