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SubjectRe: [PATCH v3 0/2] Document memory-to-memory video codec interfaces
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On 01/24/19 11:04, Tomasz Figa wrote:
> 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.

Thank you very much for this v3.

I've updated the spec with this v3 + Alexandre's v2 incorporated here:

https://hverkuil.home.xs4all.nl/codec-api/uapi/v4l/dev-mem2mem.html

I plan to review this as soon as I can because I really would like to
get this merged for 5.1.

Regards,

Hans

>
> 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
>

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