Re: [RFC v2 2/2] spice: Add an option to forward the dmabuf directly to the encoder (v2)

[Gerd Hoffmann]

  Hi,

> Here is the flow of things from the Qemu side:
> - Call gl_scanout (to update the fd) and gl_draw_async just like
>   in the local display case.

Ok.

> - Additionally, create an update with the cmd set to QXL_CMD_DRAW
>   to trigger the creation of a new drawable (associated with the fd)
>   by the Spice server.
> - Wait (or block) until the Encoder is done encoding the content.
> - Unblock the pipeline once the async completion cookie is received.

Care to explain?  For qemu it should make a difference what spice-server
does with the dma-bufs passed (local display / encode video + send to
remote).

>  #ifdef HAVE_SPICE_GL
> +        } else if (spice_dmabuf_encode) {
> +            if (g_strcmp0(preferred_codec, "gstreamer:h264")) {
> +                error_report("dmabuf-encode=on currently only works and 
> tested"
> +                             "with gstreamer:h264");
> +                exit(1);
> +            }

IMHO we should not hard-code todays spice-server capabilities like this.
For starters this isn't true for spice-server versions which don't (yet)
have your patches.  Also the capability might depend on hardware
support.  IMHO we need some feature negotiation between qemu and spice
here.

take care,
  Gerd