Re: [PATCH v2 1/3] media: uapi: add WebP uAPI

[Hugues FRUCHET <hugues.fruchet@foss.st.com>]

Hi Nicolas,

thanks for review,

On 11/20/24 15:21, Nicolas Dufresne wrote:
> Hi Hughe,
> 
> thanks for the update.
> 
> Le mercredi 20 novembre 2024 à 12:01 +0100, Hugues Fruchet a écrit :
>> This patch adds the WebP picture decoding kernel uAPI.
>>
>> This design is based on currently available VP8 API implementation and
>> aims to support the development of WebP stateless video codecs
>> on Linux.
>>
>> Signed-off-by: Hugues Fruchet <hugues.fruchet@foss.st.com>
>> ---
>>   Documentation/userspace-api/media/v4l/biblio.rst  |  9 +++++++++
>>   .../userspace-api/media/v4l/pixfmt-compressed.rst | 15 +++++++++++++++
>>   drivers/media/v4l2-core/v4l2-ioctl.c              |  1 +
>>   include/uapi/linux/videodev2.h                    |  1 +
>>   4 files changed, 26 insertions(+)
>>
>> diff --git a/Documentation/userspace-api/media/v4l/biblio.rst b/Documentation/userspace-api/media/v4l/biblio.rst
>> index 35674eeae20d..df3e963fc54f 100644
>> --- a/Documentation/userspace-api/media/v4l/biblio.rst
>> +++ b/Documentation/userspace-api/media/v4l/biblio.rst
>> @@ -447,3 +447,12 @@ AV1
>>   :title:     AV1 Bitstream & Decoding Process Specification
>>   
>>   :author:    Peter de Rivaz, Argon Design Ltd, Jack Haughton, Argon Design Ltd
>> +
>> +.. _webp:
>> +
>> +WEBP
>> +====
>> +
>> +:title:     WEBP picture Bitstream & Decoding Process Specification
>> +
>> +:author:    Google (https://developers.google.com/speed/webp)
>> diff --git a/Documentation/userspace-api/media/v4l/pixfmt-compressed.rst b/Documentation/userspace-api/media/v4l/pixfmt-compressed.rst
>> index 806ed73ac474..e664e70b0619 100644
>> --- a/Documentation/userspace-api/media/v4l/pixfmt-compressed.rst
>> +++ b/Documentation/userspace-api/media/v4l/pixfmt-compressed.rst
>> @@ -169,6 +169,21 @@ Compressed Formats
>>   	this pixel format. The output buffer must contain the appropriate number
>>   	of macroblocks to decode a full corresponding frame to the matching
>>   	capture buffer.
>> +    * .. _V4L2-PIX-FMT-WEBP-FRAME:
>> +
>> +      - ``V4L2_PIX_FMT_WEBP_FRAME``
>> +      - 'WEBP'
>> +      - WEBP VP8 parsed frame, excluding WEBP RIFF header, keeping only the VP8
>> +	bistream including the frame header, as extracted from the container.
>> +	This format is adapted for stateless video decoders that implement a
>> +	WEBP pipeline with the :ref:`stateless_decoder`.
>> +	Metadata associated with the frame to decode is required to be passed
>> +	through the ``V4L2_CID_STATELESS_VP8_FRAME`` control.
>> +	See the :ref:`associated Codec Control IDs <v4l2-codec-stateless-vp8>`.
>> +	Exactly one output and one capture buffer must be provided for use with
>> +	this pixel format. The output buffer must contain the appropriate number
>> +	of macroblocks to decode a full corresponding frame to the matching
>> +	capture buffer.
> 
> I wonder if we should document the constraints, I think
> V4L2_VP8_FRAME_FLAG_KEY_FRAME must be set, which imply that last/golden/alt
> timestamp are ignored.

I will add something about that.

> 
> With that clarified:
> 
> Reviewed-by: Nicolas Dufresne <nicolas.dufresne@collabora.com>
> 
>>
>>   
>>       * .. _V4L2-PIX-FMT-VP9:
>>   
>> diff --git a/drivers/media/v4l2-core/v4l2-ioctl.c b/drivers/media/v4l2-core/v4l2-ioctl.c
>> index 0304daa8471d..e2ff03d0d773 100644
>> --- a/drivers/media/v4l2-core/v4l2-ioctl.c
>> +++ b/drivers/media/v4l2-core/v4l2-ioctl.c
>> @@ -1501,6 +1501,7 @@ static void v4l_fill_fmtdesc(struct v4l2_fmtdesc *fmt)
>>   		case V4L2_PIX_FMT_VC1_ANNEX_L:	descr = "VC-1 (SMPTE 412M Annex L)"; break;
>>   		case V4L2_PIX_FMT_VP8:		descr = "VP8"; break;
>>   		case V4L2_PIX_FMT_VP8_FRAME:    descr = "VP8 Frame"; break;
>> +		case V4L2_PIX_FMT_WEBP_FRAME:    descr = "WEBP VP8 Frame"; break;
>>   		case V4L2_PIX_FMT_VP9:		descr = "VP9"; break;
>>   		case V4L2_PIX_FMT_VP9_FRAME:    descr = "VP9 Frame"; break;
>>   		case V4L2_PIX_FMT_HEVC:		descr = "HEVC"; break; /* aka H.265 */
>> diff --git a/include/uapi/linux/videodev2.h b/include/uapi/linux/videodev2.h
>> index e7c4dce39007..09fff269e852 100644
>> --- a/include/uapi/linux/videodev2.h
>> +++ b/include/uapi/linux/videodev2.h
>> @@ -757,6 +757,7 @@ struct v4l2_pix_format {
>>   #define V4L2_PIX_FMT_VC1_ANNEX_L v4l2_fourcc('V', 'C', '1', 'L') /* SMPTE 421M Annex L compliant stream */
>>   #define V4L2_PIX_FMT_VP8      v4l2_fourcc('V', 'P', '8', '0') /* VP8 */
>>   #define V4L2_PIX_FMT_VP8_FRAME v4l2_fourcc('V', 'P', '8', 'F') /* VP8 parsed frame */
>> +#define V4L2_PIX_FMT_WEBP_FRAME v4l2_fourcc('W', 'B', 'P', 'F') /* WEBP VP8 parsed frame */
>>   #define V4L2_PIX_FMT_VP9      v4l2_fourcc('V', 'P', '9', '0') /* VP9 */
>>   #define V4L2_PIX_FMT_VP9_FRAME v4l2_fourcc('V', 'P', '9', 'F') /* VP9 parsed frame */
>>   #define V4L2_PIX_FMT_HEVC     v4l2_fourcc('H', 'E', 'V', 'C') /* HEVC aka H.265 */
> 

BR,
Hugues.