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Subject[PATCH v3 0/2] Document memory-to-memory video codec interfaces
Date
Late happy new year everyone. It's been a while, but here is the v3 of
the stateful mem2mem codec interfaces documentation. Sorry for taking so
long time to respin. (Again.)

This series attempts to add the documentation of what was discussed
during Media Workshops at LinuxCon Europe 2012 in Barcelona and then
later Embedded Linux Conference Europe 2014 in Düsseldorf and then
eventually written down by Pawel Osciak and tweaked a bit by Chrome OS
video team (but mostly in a cosmetic way or making the document more
precise), during the several years of Chrome OS using the APIs in
production.

Note that most, if not all, of the API is already implemented in
existing mainline drivers, such as s5p-mfc or mtk-vcodec. Intention of
this series is just to formalize what we already have.

Thanks everyone for the huge amount of useful comments for the RFC and
v1. Much of the credits should go to Pawel Osciak too, for writing most
of the original text of the initial RFC.

Changes since v2:
(https://lore.kernel.org/patchwork/cover/1002474/)
Decoder:
- Specified that the initial source change event is signaled
regardless of whether the client-set format matches the
stream format.
- Dropped V4L2_CID_MIN_BUFFERS_FOR_OUTPUT since it's meaningless
for the bitstream input buffers of decoders.
- Explicitly stated that VIDIOC_REQBUFS is not allowed on CAPTURE
if the stream information is not available.
- Described decode error handling.
- Mentioned that timestamps can be observed after a seek to
determine whether the CAPTURE buffers originated from before
or after the seek.
- Explicitly stated that after a pair of V4L2_DEC_CMD_STOP and
V4L2_DEC_CMD_START, the decoder is not reset and preserves
all the state.

Encoder:
- Specified that width and height of CAPTURE format are ignored
and always zero.
- Explicitly noted the common use case for the CROP target with
macroblock-unaligned video resolutions.
- Added a reference to Request API.
- Dropped V4L2_CID_MIN_BUFFERS_FOR_CAPTURE since it's meaningless
for the bitstream output buffers of encoders.
- Explicitly stated that after a pair of V4L2_ENC_CMD_STOP and
V4L2_ENC_CMD_START, the encoder is not reset and preserves
all the state.

General:
- Dropped format enumeration from "Initialization", since it's already
a part of "Querying capabilities".
- Many spelling, grammar, stylistic, etc. changes.
- Changed the style of note blocks.
- Rebased onto Hans' documentation cleanup series.
(https://patchwork.kernel.org/cover/10775407/
https://patchwork.kernel.org/patch/10776737/)
- Moved the interfaces under the "Video Memory-To-Memory Interface"
section.

For changes since v1 see the v2:
https://lore.kernel.org/patchwork/cover/1002474/

For changes since RFC see the v1:
https://patchwork.kernel.org/cover/10542207/

Tomasz Figa (2):
media: docs-rst: Document memory-to-memory video decoder interface
media: docs-rst: Document memory-to-memory video encoder interface

Documentation/media/uapi/v4l/dev-decoder.rst | 1076 +++++++++++++++++
Documentation/media/uapi/v4l/dev-encoder.rst | 586 +++++++++
Documentation/media/uapi/v4l/dev-mem2mem.rst | 6 +
Documentation/media/uapi/v4l/pixfmt-v4l2.rst | 10 +
Documentation/media/uapi/v4l/v4l2.rst | 12 +-
.../media/uapi/v4l/vidioc-decoder-cmd.rst | 40 +-
.../media/uapi/v4l/vidioc-encoder-cmd.rst | 38 +-
Documentation/media/uapi/v4l/vidioc-g-fmt.rst | 14 +
8 files changed, 1752 insertions(+), 30 deletions(-)
create mode 100644 Documentation/media/uapi/v4l/dev-decoder.rst
create mode 100644 Documentation/media/uapi/v4l/dev-encoder.rst

--
2.20.1.321.g9e740568ce-goog

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