[Spice-devel] RFC: Media redirection for Spice remote computing solution, an event for FOSDEM'14, Virtualization dev room

[Fedor Lyakhov]

Hi Steven,

On Mon, Dec 2, 2013 at 7:14 PM, Steven Newbury <steve at snewbury.org.uk> wrote:
> On Mon, 2013-12-02 at 18:16 +0400, Fedor Lyakhov wrote:
>> Thanks, David!
>>
>> We have an internal proof of concept based on private VoIP softphone,
>> Thrift over TCP as RPC and Google WebRTC as Media Engine - and the
>> softphone is capable of audio calls and remote control of audio
>> devices. So now we're confident it can work.
>>
>> We hope to create open-source prototype for a demo GStreamer-based
>> audio player by the end of January. Depending on how it goes, we will
>> add basic integration with Spice as well.
> Wouldn't it be possible to implement this at the acceleration layer
> within the guest by providing a VDPAU or VA-API (and Windows API
> equivalent) driver which offloads the hw decoding of the media stream to
> the Spice client?
>

I'm by no means an expert in video acceleration, so I may be wrong,
but there are following considerations:
1. If I understand correctly, you're talking about video pass-through
feature. It is different from media redirection. This implementation
via acceleration layer implies the video stream is processed at
virtual machine; it may be not transcoded, just sent to the client,
but this is still suboptimal for our targeted use cases. We want to
completely off-load the media processing to the client, so the stream
doesn't even reach virtualization server at all. It must go P2P.

But I must admit this possible implementation via VAAPI can be really
the best for 2 use cases:
a) a video file is already available at the virtual machine
b) media redirection doesn't work for some reason (e.g. not supported engine)
So this is certainly useful feature...

2. What about audio? Is it just kept as is now? That may be Ok for
video playback use case, but certainly not acceptable from VoIP PoV.


-- 
Best regards,
Fedor