linux-kernel - Re: [PATCH v2 1/5] media: uapi: videodev2: Add support for AV1 stateful decoder

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Message-ID: <81d32471-0611-4653-bc87-1885d2939230@oss.qualcomm.com>
Date: Mon, 20 Oct 2025 14:55:44 -0700
From: Deepa Guthyappa Madivalara <deepa.madivalara@....qualcomm.com>
To: Nicolas Dufresne <nicolas@...fresne.ca>,
        Mauro Carvalho Chehab <mchehab@...nel.org>,
        Vikash Garodia <vikash.garodia@....qualcomm.com>,
        Dikshita Agarwal <dikshita.agarwal@....qualcomm.com>,
        Abhinav Kumar <abhinav.kumar@...ux.dev>,
        Bryan O'Donoghue <bod@...nel.org>
Cc: linux-media@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-arm-msm@...r.kernel.org, kernel test robot <lkp@...el.com>
Subject: Re: [PATCH v2 1/5] media: uapi: videodev2: Add support for AV1
 stateful decoder


On 10/17/2025 1:01 PM, Nicolas Dufresne wrote:
> Le vendredi 17 octobre 2025 à 11:35 -0700, Deepa Guthyappa Madivalara a écrit :
>> Introduce a new pixel format, V4L2_PIX_FMT_AV1, to the
>> Video4Linux2(V4L2) API. This format is intended for AV1
>> bitstreams in stateful decoding/encoding workflows.
>> The fourcc code 'AV10' is used to distinguish
>> this format from the existing V4L2_PIX_FMT_AV1_FRAME,
>> which is used for stateless AV1 decoder implementation.
>>
>> Signed-off-by: Deepa Guthyappa Madivalara <deepa.madivalara@....qualcomm.com>
>> ---
>>   Documentation/userspace-api/media/v4l/pixfmt-compressed.rst | 8 ++++++++
>>   include/uapi/linux/videodev2.h                              | 1 +
>>   2 files changed, 9 insertions(+)
>>
>> diff --git a/Documentation/userspace-api/media/v4l/pixfmt-compressed.rst b/Documentation/userspace-api/media/v4l/pixfmt-compressed.rst
>> index 806ed73ac474ce0e6df00f902850db9fd0db240e..d82557a6ac30851b4fd432a5ceab969abaed2e25 100644
>> --- a/Documentation/userspace-api/media/v4l/pixfmt-compressed.rst
>> +++ b/Documentation/userspace-api/media/v4l/pixfmt-compressed.rst
>> @@ -274,6 +274,14 @@ Compressed Formats
>>           of macroblocks to decode a full corresponding frame to the matching
>>           capture buffer.
>>   
>> +    * .. _V4L2-PIX-FMT-AV1:
>> +
>> +      - ``V4L2_PIX_FMT_AV1``
>> +      - 'AV10'
>> +      - AV1 compressed video frame. This format is adapted for implementing AV1
>> +        pipeline. The decoder implements stateful video decoder and expects one
>> +        Temporal Unit per buffer from OBU-stream or AnnexB.
>> +        The encoder generates one Temporal Unit per buffer.
>>   .. raw:: latex
>>   
>>       \normalsize
>> diff --git a/include/uapi/linux/videodev2.h b/include/uapi/linux/videodev2.h
>> index becd08fdbddb857f8f2bf205d2164dc6e20e80b2..e03cfe0a5ae830595f0bf69b951ca16beaedab72 100644
>> --- a/include/uapi/linux/videodev2.h
>> +++ b/include/uapi/linux/videodev2.h
>> @@ -775,6 +775,7 @@ struct v4l2_pix_format {
>>   #define V4L2_PIX_FMT_H264_SLICE v4l2_fourcc('S', '2', '6', '4') /* H264 parsed slices */
>>   #define V4L2_PIX_FMT_HEVC_SLICE v4l2_fourcc('S', '2', '6', '5') /* HEVC parsed slices */
>>   #define V4L2_PIX_FMT_AV1_FRAME v4l2_fourcc('A', 'V', '1', 'F') /* AV1 parsed frame */
>> +#define V4L2_PIX_FMT_AV1      v4l2_fourcc('A', 'V', '1', '0') /* AV1 */
> An alternative fourcc could be to match the one used in the ISO specification,
> which is also what browsers and Android uses. It would be "av01", link to the
> spec:
>
> http://downloads.aomedia.org/assets/pdf/AV1-ISO-Base-Media-File-Format-Binding-Specification.pdf
>
> Though, we never had any requirement in this direction, its just an idea. With
> or without, I'm happy with the definition.

"av01" sounds good. It would keep it consistent with the spec.
I will update it in v3.

> Reviewed-by: Nicolas Dufresne <nicolas.dufresne@...labora.com>
>
> cheers,
> Nicolas
>
>>   #define V4L2_PIX_FMT_SPK      v4l2_fourcc('S', 'P', 'K', '0') /* Sorenson Spark */
>>   #define V4L2_PIX_FMT_RV30     v4l2_fourcc('R', 'V', '3', '0') /* RealVideo 8 */
>>   #define V4L2_PIX_FMT_RV40     v4l2_fourcc('R', 'V', '4', '0') /* RealVideo 9 & 10 */