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

[Soft Works]

> -----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.

softworkz