Re: [PATCH v9 2/9] media: v4l: Add definitions for MPEG-2 slice format and metadata

From: Hans Verkuil
Date: Mon Sep 10 2018 - 06:34:01 EST


On 09/10/2018 11:47 AM, Paul Kocialkowski wrote:
> Hi,
>
> Le lundi 10 septembre 2018 Ã 11:41 +0200, Hans Verkuil a Ãcrit :
>> On 09/07/2018 12:24 AM, Paul Kocialkowski wrote:
>>> From: Paul Kocialkowski <paul.kocialkowski@xxxxxxxxxxx>
>>>
>>> Stateless video decoding engines require both the MPEG-2 slices and
>>> associated metadata from the video stream in order to decode frames.
>>>
>>> This introduces definitions for a new pixel format, describing buffers
>>> with MPEG-2 slice data, as well as control structure sfor passing the
>>> frame metadata to drivers.
>>>
>>> This is based on work from both Florent Revest and Hugues Fruchet.
>>>
>>> Signed-off-by: Paul Kocialkowski <paul.kocialkowski@xxxxxxxxxxx>
>>> ---
>>> .../media/uapi/v4l/extended-controls.rst | 176 ++++++++++++++++++
>>> .../media/uapi/v4l/pixfmt-compressed.rst | 16 ++
>>> .../media/uapi/v4l/vidioc-queryctrl.rst | 14 +-
>>> .../media/videodev2.h.rst.exceptions | 2 +
>>> drivers/media/v4l2-core/v4l2-ctrls.c | 63 +++++++
>>> drivers/media/v4l2-core/v4l2-ioctl.c | 1 +
>>> include/media/v4l2-ctrls.h | 18 +-
>>> include/uapi/linux/v4l2-controls.h | 65 +++++++
>>> include/uapi/linux/videodev2.h | 5 +
>>> 9 files changed, 351 insertions(+), 9 deletions(-)
>>>
>>> diff --git a/Documentation/media/uapi/v4l/extended-controls.rst b/Documentation/media/uapi/v4l/extended-controls.rst
>>> index 9f7312bf3365..f1951236266a 100644
>>> --- a/Documentation/media/uapi/v4l/extended-controls.rst
>>> +++ b/Documentation/media/uapi/v4l/extended-controls.rst
>>> @@ -1497,6 +1497,182 @@ enum v4l2_mpeg_video_h264_hierarchical_coding_type -
>>>
>>>
>>>
>>> +.. _v4l2-mpeg-mpeg2:
>>> +
>>> +``V4L2_CID_MPEG_VIDEO_MPEG2_SLICE_PARAMS (struct)``
>>> + Specifies the slice parameters (as extracted from the bitstream) for the
>>> + associated MPEG-2 slice data. This includes the necessary parameters for
>>> + configuring a stateless hardware decoding pipeline for MPEG-2.
>>> + The bitstream parameters are defined according to :ref:`mpeg2part2`.
>>> +
>>> +.. c:type:: v4l2_ctrl_mpeg2_slice_params
>>> +
>>> +.. cssclass:: longtable
>>> +
>>> +.. flat-table:: struct v4l2_ctrl_mpeg2_slice_params
>>> + :header-rows: 0
>>> + :stub-columns: 0
>>> + :widths: 1 1 2
>>> +
>>> + * - __u32
>>> + - ``bit_size``
>>> + - Size (in bits) of the current slice data.
>>> + * - __u32
>>> + - ``data_bit_offset``
>>> + - Offset (in bits) to the video data in the current slice data.
>>> + * - struct :c:type:`v4l2_mpeg2_sequence`
>>> + - ``sequence``
>>> + - Structure with MPEG-2 sequence metadata, merging relevant fields from
>>> + the sequence header and sequence extension parts of the bitstream.
>>> + * - struct :c:type:`v4l2_mpeg2_picture`
>>> + - ``picture``
>>> + - Structure with MPEG-2 picture metadata, merging relevant fields from
>>> + the picture header and picture coding extension parts of the bitstream.
>>> + * - __u8
>>> + - ``quantiser_scale_code``
>>> + - Code used to determine the quantization scale to use for the IDCT.
>>> + * - __u8
>>> + - ``backward_ref_index``
>>> + - Index for the V4L2 buffer to use as backward reference, used with
>>> + B-coded and P-coded frames.
>>> + * - __u8
>>> + - ``forward_ref_index``
>>> + - Index for the V4L2 buffer to use as forward reference, used with
>>> + P-coded frames.
>>
>> Should this be "B-coded frames"?
>
> Oops, that's right, B-coded frames.
>
> Should I make a follow-up patch for that (maybe gathered with other
> changes if required)?

Follow-up patches, please. All on top of my last pull request that adds the
cedrus driver.

Regards,

Hans