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

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Message-ID: <2409ba6607e85acf3dbbaed394487fa8e92d93df.camel@paulk.fr>
Date:   Mon, 10 Sep 2018 11:47:47 +0200
From:   Paul Kocialkowski <contact@...lk.fr>
To:     Hans Verkuil <hverkuil@...all.nl>, linux-media@...r.kernel.org,
        devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org, devel@...verdev.osuosl.org
Cc:     Mauro Carvalho Chehab <mchehab@...nel.org>,
        Rob Herring <robh+dt@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Maxime Ripard <maxime.ripard@...tlin.com>,
        Chen-Yu Tsai <wens@...e.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Thomas Petazzoni <thomas.petazzoni@...tlin.com>,
        linux-sunxi@...glegroups.com, Randy Li <ayaka@...lik.info>,
        Ezequiel Garcia <ezequiel@...labora.com>,
        Tomasz Figa <tfiga@...omium.org>,
        Alexandre Courbot <acourbot@...omium.org>,
        Philipp Zabel <p.zabel@...gutronix.de>,
        Laurent Pinchart <laurent.pinchart@...asonboard.com>,
        Sakari Ailus <sakari.ailus@...ux.intel.com>
Subject: Re: [PATCH v9 2/9] media: v4l: Add definitions for MPEG-2 slice
 format and metadata

Hi,

Le lundi 10 septembre 2018 à 11:41 +0200, Hans Verkuil a écrit :
> On 09/07/2018 12:24 AM, Paul Kocialkowski wrote:
> > From: Paul Kocialkowski <paul.kocialkowski@...tlin.com>
> > 
> > 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@...tlin.com>
> > ---
> >  .../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)?

Cheers,

Paul

-- 
Developer of free digital technology and hardware support.

Website: https://www.paulk.fr/
Coding blog: https://code.paulk.fr/
Git repositories: https://git.paulk.fr/ https://git.code.paulk.fr/

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