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

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Message-ID: <bebe83bf-bfd7-437f-9820-c907a12d5624@oss.qualcomm.com>
Date: Thu, 2 Oct 2025 14:52:19 -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
Subject: Re: [PATCH 1/5] media: uapi: videodev2: Add support for AV1 stateful
 decoder


On 10/2/2025 12:42 PM, Nicolas Dufresne wrote:
> Hi,
>
> Le mercredi 01 octobre 2025 à 12:00 -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..043ec57d7d48a36005f2a0121a5bc7b733d0
>> 6590 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 as stateful video decoder. The decoder expects one Temporal
> I would do a small edit here. Instead of stating that this is for decoders, I
> would rather document the intended behaviour for video codec. This way the spec
> remains open for CAPTURE driver to produce AV1 in the future, or OUTPUT driver
> consuming it in the future.
>
>> +        Unit per buffer from OBU-stream or AnnexB.
>> +        The encoder generates one Temporal Unit per buffer.
> Otherwise I'm fine with the proposal of using TU aligned. Similar to other
> codecs, we can always allow adapting the behaviour using controls, keeping this
> as the mandatory default so it just works regardless of the HW we run on.
>
> regards,
> Nicolas

Agreed. Thank you. I will update it in the next patch.

Regards,
Deepa

>>   .. raw:: latex
>>   
>>       \normalsize
>> diff --git a/include/uapi/linux/videodev2.h b/include/uapi/linux/videodev2.h
>> index
>> becd08fdbddb857f8f2bf205d2164dc6e20e80b2..4c07ad6afd45d6a56d19d65fd25f091d8172
>> 5823 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
>> (stateful) */
>>   #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 */