Re: [PATCHv2 01/12] videodev2.h: add V4L2_FMT_FLAG_CONTINUOUS_BYTESTREAM

[Paul Kocialkowski <paul.kocialkowski@bootlin.com>]

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Hi,

On Mon 12 Aug 19, 13:05, Hans Verkuil wrote:
> Add an enum_fmt format flag to specifically tag coded formats where
> full bytestream parsing is supported by the device.
> 
> Some stateful decoders are capable of fully parsing a bytestream,
> but others require that userspace pre-parses the bytestream into
> frames or fields (see the corresponding pixelformat descriptions
> for details).
> 
> If this flag is set, then this pre-parsing step is not required
> (but still possible, of course).

Although I wasn't involved with the initial issue, looks good to me!

Reviewed-by: Paul Kocialkowski <paul.kocialkowski@bootlin.com>

Cheers,

Paul

> Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
> ---
>  Documentation/media/uapi/v4l/vidioc-enum-fmt.rst | 8 ++++++++
>  Documentation/media/videodev2.h.rst.exceptions   | 1 +
>  include/uapi/linux/videodev2.h                   | 5 +++--
>  3 files changed, 12 insertions(+), 2 deletions(-)
> 
> diff --git a/Documentation/media/uapi/v4l/vidioc-enum-fmt.rst b/Documentation/media/uapi/v4l/vidioc-enum-fmt.rst
> index 822d6730e7d2..ebc05ce74bdf 100644
> --- a/Documentation/media/uapi/v4l/vidioc-enum-fmt.rst
> +++ b/Documentation/media/uapi/v4l/vidioc-enum-fmt.rst
> @@ -127,6 +127,14 @@ one until ``EINVAL`` is returned.
>        - This format is not native to the device but emulated through
>  	software (usually libv4l2), where possible try to use a native
>  	format instead for better performance.
> +    * - ``V4L2_FMT_FLAG_CONTINUOUS_BYTESTREAM``
> +      - 0x0004
> +      - The hardware decoder for this compressed bytestream format (aka coded
> +	format) is capable of parsing a continuous bytestream. Applications do
> +	not need to parse the bytestream themselves to find the boundaries
> +	between frames/fields. This flag can only be used in combination with
> +	the ``V4L2_FMT_FLAG_COMPRESSED`` flag, since this applies to compressed
> +	formats only. This flag is valid for stateful decoders only.
>  
>  
>  Return Value
> diff --git a/Documentation/media/videodev2.h.rst.exceptions b/Documentation/media/videodev2.h.rst.exceptions
> index 8e7d3492d248..a0640b6d0f68 100644
> --- a/Documentation/media/videodev2.h.rst.exceptions
> +++ b/Documentation/media/videodev2.h.rst.exceptions
> @@ -180,6 +180,7 @@ replace define V4L2_PIX_FMT_FLAG_PREMUL_ALPHA reserved-formats
>  # V4L2 format flags
>  replace define V4L2_FMT_FLAG_COMPRESSED fmtdesc-flags
>  replace define V4L2_FMT_FLAG_EMULATED fmtdesc-flags
> +replace define V4L2_FMT_FLAG_CONTINUOUS_BYTESTREAM fmtdesc-flags
>  
>  # V4L2 timecode types
>  replace define V4L2_TC_TYPE_24FPS timecode-type
> diff --git a/include/uapi/linux/videodev2.h b/include/uapi/linux/videodev2.h
> index 2427bc4d8eba..67077d52c59d 100644
> --- a/include/uapi/linux/videodev2.h
> +++ b/include/uapi/linux/videodev2.h
> @@ -774,8 +774,9 @@ struct v4l2_fmtdesc {
>  	__u32		    reserved[4];
>  };
>  
> -#define V4L2_FMT_FLAG_COMPRESSED 0x0001
> -#define V4L2_FMT_FLAG_EMULATED   0x0002
> +#define V4L2_FMT_FLAG_COMPRESSED		0x0001
> +#define V4L2_FMT_FLAG_EMULATED			0x0002
> +#define V4L2_FMT_FLAG_CONTINUOUS_BYTESTREAM	0x0004
>  
>  	/* Frame Size and frame rate enumeration */
>  /*
> -- 
> 2.20.1
> 

-- 
Paul Kocialkowski, Bootlin
Embedded Linux and kernel engineering
https://bootlin.com

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