From: Gerd Hoffmann <kraxel@redhat.com>
To: Keiichi Watanabe <keiichiw@chromium.org>
Cc: "Tomasz Figa" <tfiga@chromium.org>,
"Dmitry Sepp" <dmitry.sepp@opensynergy.com>,
virtio-dev@lists.oasis-open.org,
"Linux Media Mailing List" <linux-media@vger.kernel.org>,
"Alexandre Courbot" <acourbot@chromium.org>,
"Alex Lau" <alexlau@chromium.org>,
"Dylan Reid" <dgreid@chromium.org>,
"Stéphane Marchesin" <marcheu@chromium.org>,
"Pawel Osciak" <posciak@chromium.org>,
"David Stevens" <stevensd@chromium.org>,
"Hans Verkuil" <hverkuil@xs4all.nl>,
"Daniel Vetter" <daniel@ffwll.ch>
Subject: Re: [virtio-dev] [RFC RESEND] virtio-video: Add virtio video device specification
Date: Wed, 20 Nov 2019 12:29:29 +0100 [thread overview]
Message-ID: <20191120112929.gvsne7ykvcyw65lu@sirius.home.kraxel.org> (raw)
In-Reply-To: <CAD90Vcbr7L2KsyDxPeoKPRt6y_ai8xkJ=J0JCGsW6tGZJGH=0A@mail.gmail.com>
Hi,
> > > > 3. No support for getting plane requirements from the device (sg vs contig,
> > > > size, stride alignment, plane count).
> > >
> > > There is actually a bigger difference that results in that. Vdec
> > > assumes host-allocated buffers coming from a different device, e.g.
> > > virtio-gpu and the host having the right knowledge to allocate the
> > > buffers correctly. This is related to the fact that it's generally
> > > difficult to convey all the allocation constraints in a generic
> > > manner.
> >
> > Yep, buffer handling is tricky, especially when it comes to decoding
> > directly to gpu buffers and also when supporting playback of
> > drm-protected streams where the guest might not be allowed to access
> > the stream data.
> Also, if we decide to have a buffer sharing device as Gerd suggested
> in a different thread,
> we'll get less overlaps between video codec feature and camera feature.
> e.g. VIRTIO_VIDEO_T_RESOURCE_* would be simplified. (or removed?)
Disclaimer: Havn't found the time yet to go over both virtio-video and
virtio-vdec in detail.
> As Tomasz said, I think virtio-vdec can be modified to support
> encoding as well without big changes. I'm happy to update our
> protocol and driver implementation to support encoding if needed.
I think it makes sense to have a rough plan first ;)
Is there a virtio-video implementation too?
When it comes to buffer handling: I don't like that virtio-vdec depends
on virtio-gpu for buffer handling. Allowing sharing buffers between
virtio-vdec and virtio-gpu (and possibly other devices) makes sense as
an optional extension. But IMO the encoder/decoder device should be
able to operate as stand-alone device.
cheers,
Gerd
next prev parent reply other threads:[~2019-11-20 11:29 UTC|newest]
Thread overview: 38+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-11-05 19:19 [RFC RESEND] virtio-video: Add virtio video device specification Dmitry Sepp
2019-11-07 9:56 ` [virtio-dev] " Gerd Hoffmann
2019-11-07 13:09 ` Dmitry Sepp
2019-11-08 7:49 ` Gerd Hoffmann
2019-11-08 7:58 ` Tomasz Figa
2019-11-08 9:51 ` Dmitry Sepp
2019-11-08 7:50 ` Tomasz Figa
2019-11-08 9:05 ` Gerd Hoffmann
2019-11-08 9:28 ` Keiichi Watanabe
2019-11-20 11:29 ` Gerd Hoffmann [this message]
2019-11-21 10:54 ` Dmitry Sepp
2019-12-04 7:48 ` Keiichi Watanabe
2019-12-04 9:16 ` Gerd Hoffmann
2019-12-04 19:11 ` Enrico Granata
2019-12-05 8:21 ` Keiichi Watanabe
2019-12-06 7:32 ` Gerd Hoffmann
2019-12-06 12:30 ` Keiichi Watanabe
2019-12-06 15:50 ` Enrico Granata
2019-12-09 13:43 ` Keiichi Watanabe
2019-12-09 10:46 ` Gerd Hoffmann
2019-12-09 11:38 ` Dmitry Sepp
2019-12-09 13:17 ` Keiichi Watanabe
2019-12-09 14:19 ` Dmitry Sepp
[not found] ` <CAPR809t2X3eEZj14Y-0CdnmzGZFhWKt2vwFSZBrEZbChQpmU_w@mail.gmail.com>
2019-12-10 13:16 ` Dmitry Sepp
2019-12-12 5:39 ` Keiichi Watanabe
2019-12-12 10:34 ` Dmitry Sepp
2019-12-13 14:20 ` Keiichi Watanabe
2019-12-13 16:31 ` Keiichi Watanabe
2019-12-20 14:24 ` Dmitry Sepp
2019-12-20 15:01 ` Keiichi Watanabe
2019-12-13 14:58 ` Christophe de Dinechin
2019-12-16 8:09 ` Tomasz Figa
2019-12-16 10:32 ` Gerd Hoffmann
2019-12-17 13:15 ` Tomasz Figa
2019-12-17 13:39 ` Gerd Hoffmann
2019-12-17 14:09 ` Keiichi Watanabe
2019-12-17 16:13 ` Dmitry Sepp
2019-12-18 6:43 ` Gerd Hoffmann
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