[EXT] Re: [PATCH 1/2] media: add RealMedia format

[Ming Qian]

>From: Nicolas Dufresne <nicolas at ndufresne.ca>
>Sent: 2023年1月11日 22:28
>To: Ming Qian <ming.qian at nxp.com>; mchehab at kernel.org; hverkuil-
>cisco at xs4all.nl
>Cc: shawnguo at kernel.org; robh+dt at kernel.org; s.hauer at pengutronix.de;
>kernel at pengutronix.de; festevam at gmail.com; dl-linux-imx <linux-
>imx at nxp.com>; X.H. Bao <xiahong.bao at nxp.com>; Ming Zhou
><ming.zhou at nxp.com>; linux-media at vger.kernel.org; linux-
>kernel at vger.kernel.org; linux-arm-kernel at lists.infradead.org
>Subject: [EXT] Re: [PATCH 1/2] media: add RealMedia format
>
>Caution: EXT Email
>
>Hi Ming,
>
>sorry for the late reply ...
>
>Le mardi 20 décembre 2022 à 16:39 +0800, Ming Qian a écrit :
>> RealMedia is a proprietary multimedia container format created by
>> RealNetworks with the filename extension .rm.
>> RealMedia is generally used in conjunction with RealVideo and
>> RealAudio, while also being used for streaming content over the Internet.
>>
>> Signed-off-by: Ming Qian <ming.qian at nxp.com>
>> ---
>>  .../userspace-api/media/v4l/pixfmt-compressed.rst     | 11 +++++++++++
>>  drivers/media/v4l2-core/v4l2-ioctl.c                  |  1 +
>>  include/uapi/linux/videodev2.h                        |  1 +
>>  3 files changed, 13 insertions(+)
>>
>> diff --git
>> a/Documentation/userspace-api/media/v4l/pixfmt-compressed.rst
>> b/Documentation/userspace-api/media/v4l/pixfmt-compressed.rst
>> index 8794b92fde36..31ba2c00091e 100644
>> --- a/Documentation/userspace-api/media/v4l/pixfmt-compressed.rst
>> +++ b/Documentation/userspace-api/media/v4l/pixfmt-compressed.rst
>> @@ -237,6 +237,17 @@ 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-RV:
>> +
>> +      - ``V4L2_PIX_FMT_RV``
>> +      - 'RealMedia'
>> +      - RealMedia is a proprietary multimedia container format
>> +        created by RealNetworks with the filename extension .rm.
>> +        RealMedia is generally used in conjunction with RealVideo and
>RealAudio,
>> +        while also being used for streaming content over the Internet.
>> +        Typically these streams are in CBR (constant bitrate),
>> +        but a container for VBR (variable bitrate) streams
>> +        named RMVB (RealMedia variable bitrate) has been developed.
>
>I'm a bit confused with the description here. It describes the RealMedia (RM)
>container format, but what you wanted is a RealVideo encoding (RV).
>
>A quick search into FFMpeg (the only Open Source software decoder I could
>find), the RealVideo comes in 4 incompatible flavours, RV10/RV20/RV30/RV40
>also known as  RealVideo 1 / G2 / 8 / 9+10. I think the format here should be a
>RealVideo format, and it should specify the flavours you want to support
>(probably only RV40).
>
>regards,
>Nicolas

Hi Nicolas,
    Yes, you're right, I confused the encoding format with the container format,
I'll check and correct it.
     Thanks very much

Ming

>
>>
>>  .. raw:: latex
>>
>> diff --git a/drivers/media/v4l2-core/v4l2-ioctl.c
>> b/drivers/media/v4l2-core/v4l2-ioctl.c
>> index 9b5b04b8aa69..a4d12eea7fc5 100644
>> --- a/drivers/media/v4l2-core/v4l2-ioctl.c
>> +++ b/drivers/media/v4l2-core/v4l2-ioctl.c
>> @@ -1473,6 +1473,7 @@ 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_RV:           descr = "RealMedia"; 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..a7a7969ae4f8
>> 100644
>> --- a/include/uapi/linux/videodev2.h
>> +++ b/include/uapi/linux/videodev2.h
>> @@ -740,6 +740,7 @@ 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_SPK      v4l2_fourcc('S', 'P', 'K', '0') /* Sorenson Spark
>*/
>> +#define V4L2_PIX_FMT_RV       v4l2_fourcc('R', 'V', '0', '0') /* RealMedia */
>>
>>  /*  Vendor-specific formats   */
>>  #define V4L2_PIX_FMT_CPIA1    v4l2_fourcc('C', 'P', 'I', 'A') /* cpia1 YUV */