[PATCHv3 0/5] Stateful Encoding: final bits

[Hans Verkuil <hverkuil-cisco@xs4all.nl>]

This series adds the encoder spec and updates the VIDIOC_G/S_PARM
documentation.

This is a follow-up of the original "Stateful Encoding: final bits"
series (1). 

The patches in that series that add support for V4L2_CID_MPEG_VIDEO_ENC_FRAME_RATE
and V4L2_BUF_FLAG_TOO_SMALL have been dropped (the first is not necessary
and the second can be skipped for now, see the irc discussion with
Nicolas [3]).

The encoder spec has been updated since [2] with the following
changes:

- Document the optional VIDIOC_ENUM_FRAMEINTERVALS ioctl.

- Document how to use VIDIOC_S_PARM:

  1) calling S_PARM for the OUTPUT queue sets both the raw frame interval
     (this is a hint only) and the coded frame interval.

  2) calling S_PARM for the CAPTURE queue sets the coded frame interval
     only. This is optional and can be used for off-line encoding. In
     that case the OUTPUT frame interval can be used by the driver to
     schedule multiple encoders.
 
  Ideally S_PARM for the OUTPUT queue would just provide a hint, but
  existing encoder drivers all use S_PARM for the OUTPUT queue to
  define the coded frame interval, and that can't be changed.

- Added a note that if a capture buffer is too small it will be
  returned with V4L2_BUF_FLAG_ERROR and that more work has to be
  done to properly support this corner case.

- Clarify in the 'Encoding' section that there are more reasons
  why 'a buffer queued to OUTPUT may result in more than one buffer
  produced on CAPTURE'.

Added in v3:

- Fix some minor typos.

- Make it more explicit that setting S_PARM(OUTPUT) also sets the
  CAPTURE frame interval.

- Added a new V4L2_FMT_FLAG_ENC_CAP_FRAME_INTERVAL flag to indicate
  that S_PARM(CAPTURE) can be set separately.

I think that with these changes this stateful encoder spec is ready
to be merged.

Regards,

	Hans

[1] https://lore.kernel.org/linux-media/20191119113457.57833-6-hverkuil-cisco@xs4all.nl/T/
[2] https://www.mail-archive.com/linux-media@vger.kernel.org/msg149211.html
[3] https://linuxtv.org/irc/irclogger_log/v4l?date=2020-05-19,Tue

Hans Verkuil (4):
  vidioc-g-parm.rst: update the VIDIOC_G/S_PARM documentation
  dev-decoder.rst: small fixes
  videodev2.h: add V4L2_FMT_FLAG_ENC_CAP_FRAME_INTERVAL flag
  dev-encoder.rst: add reference to V4L2_FMT_FLAG_ENC_CAP_FRAME_INTERVAL

Tomasz Figa (1):
  media: docs-rst: Document memory-to-memory video encoder interface

 .../userspace-api/media/v4l/dev-decoder.rst   |   6 +-
 .../userspace-api/media/v4l/dev-encoder.rst   | 729 ++++++++++++++++++
 .../userspace-api/media/v4l/dev-mem2mem.rst   |   1 +
 .../userspace-api/media/v4l/pixfmt-v4l2.rst   |   5 +
 .../userspace-api/media/v4l/v4l2.rst          |   2 +
 .../media/v4l/vidioc-encoder-cmd.rst          |  51 +-
 .../media/v4l/vidioc-enum-fmt.rst             |  30 +-
 .../userspace-api/media/v4l/vidioc-g-parm.rst |  51 +-
 .../media/videodev2.h.rst.exceptions          |   1 +
 include/uapi/linux/videodev2.h                |   1 +
 10 files changed, 830 insertions(+), 47 deletions(-)
 create mode 100644 Documentation/userspace-api/media/v4l/dev-encoder.rst

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