Re: [PATCH 1/9] CHROMIUM: v4l: Add H264 low-level decoder API compound controls.

[Ezequiel Garcia <ezequiel@collabora.com>]

On Wed, 2018-06-13 at 16:07 +0200, Maxime Ripard wrote:
> From: Pawel Osciak <posciak@chromium.org>
> 
> Signed-off-by: Pawel Osciak <posciak@chromium.org>
> Reviewed-by: Wu-cheng Li <wuchengli@chromium.org>
> Tested-by: Tomasz Figa <tfiga@chromium.org>
> [rebase44(groeck): include linux/types.h in v4l2-controls.h]
> Signed-off-by: Guenter Roeck <groeck@chromium.org>
> Signed-off-by: Maxime Ripard <maxime.ripard@bootlin.com>
> ---
> 
[..]
> diff --git a/include/uapi/linux/videodev2.h b/include/uapi/linux/videodev2.h
> index 242a6bfa1440..4b4a1b25a0db 100644
> --- a/include/uapi/linux/videodev2.h
> +++ b/include/uapi/linux/videodev2.h
> @@ -626,6 +626,7 @@ struct v4l2_pix_format {
>  #define V4L2_PIX_FMT_H264     v4l2_fourcc('H', '2', '6', '4') /* H264 with start codes */
>  #define V4L2_PIX_FMT_H264_NO_SC v4l2_fourcc('A', 'V', 'C', '1') /* H264 without start codes */
>  #define V4L2_PIX_FMT_H264_MVC v4l2_fourcc('M', '2', '6', '4') /* H264 MVC */
> +#define V4L2_PIX_FMT_H264_SLICE v4l2_fourcc('S', '2', '6', '4') /* H264 parsed slices */

As pointed out by Tomasz, the Rockchip VPU driver expects start codes [1], so the userspace
should be aware of it. Perhaps we could document this pixel format better as:

#define V4L2_PIX_FMT_H264_SLICE v4l2_fourcc('S', '2', '6', '4') /* H264 parsed slices with start codes */

And introduce another pixel format:

#define V4L2_PIX_FMT_H264_SLICE_NO_SC v4l2_fourcc(TODO) /* H264 parsed slices without start codes */

For cedrus to use, as it seems it doesn't need start codes.

How does it sound? 

[1] https://cs.chromium.org/chromium/src/media/gpu/v4l2/v4l2_slice_video_decode_accelerator.cc?rcl=63129434aeacf0f54bbae96814f10cf64e3e6c35&l=2438