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

[Albert Esteve <aesteve@redhat.com>]

New attempt of including virtio-media
device specification.

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

-- 
2.47.1