RE: [EXT] Re: [PATCH v3 1/2] media: add RealVideo format RV30 and RV40

[Ming Qian]

>-----Original Message-----
>From: Nicolas Dufresne <nicolas@xxxxxxxxxxxx>
>Sent: 2023年1月17日 4:47
>To: Ming Qian <ming.qian@xxxxxxx>; mchehab@xxxxxxxxxx; hverkuil-
>cisco@xxxxxxxxx
>Cc: shawnguo@xxxxxxxxxx; robh+dt@xxxxxxxxxx; s.hauer@xxxxxxxxxxxxxx;
>kernel@xxxxxxxxxxxxxx; festevam@xxxxxxxxx; dl-linux-imx <linux-
>imx@xxxxxxx>; X.H. Bao <xiahong.bao@xxxxxxx>; Eagle Zhou
><eagle.zhou@xxxxxxx>; Tao Jiang <tao.jiang_2@xxxxxxx>; linux-
>media@xxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx; linux-arm-
>kernel@xxxxxxxxxxxxxxxxxxx
>Subject: [EXT] Re: [PATCH v3 1/2] media: add RealVideo format RV30 and
>RV40
>
>Caution: EXT Email
>
>Le vendredi 13 janvier 2023 à 12:13 +0800, Ming Qian a écrit :
>> RealVideo, or also spelled as Real Video, is a suite of proprietary
>> video compression formats developed by RealNetworks - the specific
>> format changes with the version.
>> RealVideo codecs are identified by four-character codes.
>> RV30 and RV40 are RealNetworks' proprietary H.264-based codecs.
>>
>> Signed-off-by: Ming Qian <ming.qian@xxxxxxx>
>> ---
>>  .../media/v4l/pixfmt-compressed.rst           | 21 +++++++++++++++++++
>>  drivers/media/v4l2-core/v4l2-ioctl.c          |  2 ++
>>  include/uapi/linux/videodev2.h                |  2 ++
>>  3 files changed, 25 insertions(+)
>>
>> diff --git
>> a/Documentation/userspace-api/media/v4l/pixfmt-compressed.rst
>> b/Documentation/userspace-api/media/v4l/pixfmt-compressed.rst
>> index a0230f357680..50ac095c1f16 100644
>> --- a/Documentation/userspace-api/media/v4l/pixfmt-compressed.rst
>> +++ b/Documentation/userspace-api/media/v4l/pixfmt-compressed.rst
>> @@ -237,6 +237,27 @@ Compressed Formats
>>          Metadata associated with the frame to decode is required to be passed
>>          through the ``V4L2_CID_STATELESS_FWHT_PARAMS`` control.
>>       See the :ref:`associated Codec Control ID <codec-stateless-fwht>`.
>> +    * .. _V4L2-PIX-FMT-RV30:
>> +
>> +      - ``V4L2_PIX_FMT_RV30``
>> +      - 'RV30'
>> +      - RealVideo, or also spelled as Real Video, is a suite of proprietary
>> +        video compression formats developed by RealNetworks -
>> +        the specific format changes with the version.
>> +        RealVideo codecs are identified by four-character codes.
>> +        RV30 corresponds to RealVideo 8, suspected to based largely
>> + on an early draft of H.264
>
>to *be* based on.
>
>Just a style comment too, but the flow could be improved while fixing this
>typo.
>Lines in this paragraph seems very uneven.
>
>> +    * .. _V4L2-PIX-FMT-RV40:
>> +
>> +      - ``V4L2_PIX_FMT_RV40``
>> +      - 'RV40'
>> +      - RV40 represents RealVideo 9 and RealVideo 10.
>> +        RealVideo 9, suspected to be based on H.264,
>> +        RealVideo 10, aka RV9 EHQ, This refers to
>> +        an improved encoder for the RV9 format
>> +        that is fully backwards compatible with RV9 players -
>> +        the format and decoder did not change,
>> +        only the encoder did.
>> +        As a result, it uses the same FourCC.
>
>It feels this one could be wider ? But again, this is cosmetic at this point.
>For the API changes, assuming fixed typo and improved style:
>
>Reviewed-by: Nicolas Dufresne <nicolas.dufresne@xxxxxxxxxxxxx>

Hi Nicolas,
    I'll fix the typo and improve style in v4 patch, 
    And for RV40, maybe a new fourcc like RV40E can be defined for encoding RealVideo 10. But this patch won't use this format, some encoder driver can add it in the future  if it can support encoding the RealVideo 10

Ming

>
>>
>>  .. raw:: latex
>>
>> diff --git a/drivers/media/v4l2-core/v4l2-ioctl.c
>> b/drivers/media/v4l2-core/v4l2-ioctl.c
>> index 9b5b04b8aa69..0546b00d3fc9 100644
>> --- a/drivers/media/v4l2-core/v4l2-ioctl.c
>> +++ b/drivers/media/v4l2-core/v4l2-ioctl.c
>> @@ -1473,6 +1473,8 @@ static void v4l_fill_fmtdesc(struct v4l2_fmtdesc
>*fmt)
>>               case V4L2_PIX_FMT_FWHT:         descr = "FWHT"; break; /* used in
>vicodec */
>>               case V4L2_PIX_FMT_FWHT_STATELESS:       descr = "FWHT Stateless";
>break; /* used in vicodec */
>>               case V4L2_PIX_FMT_SPK:          descr = "Sorenson Spark"; break;
>> +             case V4L2_PIX_FMT_RV30:         descr = "RealVideo 8"; break;
>> +             case V4L2_PIX_FMT_RV40:         descr = "RealVideo 9 & 10"; break;
>>               case V4L2_PIX_FMT_CPIA1:        descr = "GSPCA CPiA YUV"; break;
>>               case V4L2_PIX_FMT_WNVA:         descr = "WNVA"; break;
>>               case V4L2_PIX_FMT_SN9C10X:      descr = "GSPCA SN9C10X"; break;
>> diff --git a/include/uapi/linux/videodev2.h
>> b/include/uapi/linux/videodev2.h index 262ef10cfa02..b121154a6e24
>> 100644
>> --- a/include/uapi/linux/videodev2.h
>> +++ b/include/uapi/linux/videodev2.h
>> @@ -740,6 +740,8 @@ 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_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 */
>>
>>  /*  Vendor-specific formats   */
>>  #define V4L2_PIX_FMT_CPIA1    v4l2_fourcc('C', 'P', 'I', 'A') /* cpia1 YUV */