Re: [PATCH v5 0/1] virtio-media: Add device specification

["Alexandre Courbot" <gnurou@gmail.com>]

On Mon Jan 20, 2025 at 5:50 PM JST, Albert Esteve wrote:
> New attempt of including virtio-media
> device specification.

Thank you Albert!

On my end, I have (at long last) sent the driver for upstream review:

https://lore.kernel.org/linux-media/20250123-virtio-media-v1-1-81e2549b86b9@gmail.com/T/#u

>
> v4->v5:
> - Rewritten/clarified some parts
>   according to the reviews received.
> - Added missing links to V4L2
>   structures. Structs should
>   have a link on their first
>   appreance in the document.
> - Clarified memory type
>   semantic V4L2 equivalent.
>
> v3->v4:
> - Updated device ID to 48
>   (moved to the first free id)
> - Specified endianess on all
>   structures defined through
>   the spec (leXX)
> - Slightly improved the explanation
>   of the size (and endianess)
>   of the exchanged v4l2 structs
>   as part of the ioctl command
>   payload
> - Changed cmd_mmap offset size to
>   match the V4L2_QUERYBUF offset field
> - Fixed most comments on previous
>   version for small typos/rewrites.
>
> v2->v3:
> - Updated device ID to 49
> - Renamed virtio memory types so that
>   they are differentiated from V4L2
>   memory types
> - Memory types description slightly
>   rewritten, explicitely excluding
>   USERPTR support for guest userspace
>
> v1->v2:
> - Remove naming host/guest in the text
> - Explicitly specify endian-ness of the device
> - Change address by offset in the MMAP operation
> - Specify SHM region for MMAP operation
>
> Virtio-media came from a discussion on virtio-dev
> mailing list, which lead to presenting virtio-v4l2[1]
> specification as an alternative to virtio-video.
>
> Later, virtio-v4l2 was renamed to virtio-media[2]
> and published at:
>
> https://github.com/chromeos/virtio-media
>
> The repository above includes a virtio-media driver able
> to pass v4l2-compliance when proxying the vivid/vicodec
> virtual devices or an actual UVC camera using the
> V4L2 vhost device (available in the repository).
> It also includes a FFmpeg-based video encoder
> device. Steps to reproduce are also detailed[3].
>
> Recently, virtio-media has landed in AOSP[4].
>
> Furthermore, virtio-media got a proposal to reserve
> device ID 48, which was finally approved for
> inclusion in v1.4.
>
> There is some overlap with virtio-video in regards
> to which devices it can handle. However,
> they take different approaches, making them
> the preferable choice for different scenarios.
> Moreover, as virtio-media will likely be the virtualization
> solution for ChromeOS, Android, and possibly others, for
> media devices, this justifies the desire to include
> the specification in the next release despite
> the aforementioned overlap.
>
> Full PDF: https://drive.google.com/file/d/1XKpPDalkXcJe2ZjPpbtiOcgJRIWy-UTf/view?usp=sharing
> PDF with the media section only: https://drive.google.com/file/d/1fzvKEuY31vUF7ctQ0KK0CmfrDO5CdRFj/view?usp=sharing
>
> [1] https://mail.google.com/mail/u/0?ui=2&ik=73ebd65ebd&attid=0.1&permmsgid=msg-f:1767388565327924962&th=1887068940754ee2&view=att&disp=inline&realattid=f_libalimc0
> [2] https://www.mail-archive.com/virtio-dev@lists.oasis-open.org/msg12665.html
> [3] https://github.com/chromeos/virtio-media/blob/main/TRY_IT_OUT.md
> [4] https://cs.android.com/android/platform/superproject/main/+/main:external/virtio-media/
>
> Albert Esteve (1):
>   virtio-media: Add virtio media device specification
>
>  conformance.tex                           |  13 +-
>  content.tex                               |   1 +
>  device-types/media/description.tex        | 617 ++++++++++++++++++++++
>  device-types/media/device-conformance.tex |  12 +
>  device-types/media/driver-conformance.tex |  10 +
>  5 files changed, 649 insertions(+), 4 deletions(-)
>  create mode 100644 device-types/media/description.tex
>  create mode 100644 device-types/media/device-conformance.tex
>  create mode 100644 device-types/media/driver-conformance.tex