On 1/16/19 1:37 PM, Stanimir Varbanov wrote:
> This changes v4l2_pix_format and v4l2_plane_pix_format sizeimage
> field description to allow v4l clients to set bigger image size
> in case of variable length compressed data.
>
> Signed-off-by: Stanimir Varbanov <[email protected]>
> ---
> Documentation/media/uapi/v4l/pixfmt-v4l2-mplane.rst | 5 ++++-
> Documentation/media/uapi/v4l/pixfmt-v4l2.rst | 3 ++-
> 2 files changed, 6 insertions(+), 2 deletions(-)
>
> diff --git a/Documentation/media/uapi/v4l/pixfmt-v4l2-mplane.rst
> b/Documentation/media/uapi/v4l/pixfmt-v4l2-mplane.rst
> index 7f82dad9013a..dbe0b74e9ba4 100644
> --- a/Documentation/media/uapi/v4l/pixfmt-v4l2-mplane.rst
> +++ b/Documentation/media/uapi/v4l/pixfmt-v4l2-mplane.rst
> @@ -30,7 +30,10 @@ describing all planes of that format.
>
> * - __u32
> - ``sizeimage``
> - - Maximum size in bytes required for image data in this plane.
> + - Maximum size in bytes required for image data in this plane,
> + set by the driver. When the image consists of variable length
> + compressed data this is the maximum number of bytes required
> + to hold an image, and it is allowed to be set by the client.
> * - __u32
> - ``bytesperline``
> - Distance in bytes between the leftmost pixels in two adjacent
> diff --git a/Documentation/media/uapi/v4l/pixfmt-v4l2.rst
> b/Documentation/media/uapi/v4l/pixfmt-v4l2.rst
> index 71eebfc6d853..54b6d2b67bd7 100644
> --- a/Documentation/media/uapi/v4l/pixfmt-v4l2.rst
> +++ b/Documentation/media/uapi/v4l/pixfmt-v4l2.rst
> @@ -89,7 +89,8 @@ Single-planar format structure
> - Size in bytes of the buffer to hold a complete image, set by the
> driver. Usually this is ``bytesperline`` times ``height``. When
> the image consists of variable length compressed data this is the
> - maximum number of bytes required to hold an image.
> + maximum number of bytes required to hold an image, and it is
> + allowed to be set by the client.
> * - __u32
> - ``colorspace``
> - Image colorspace, from enum :c:type:`v4l2_colorspace`.
>
Hmm. "maximum number of bytes required to hold an image": that's not actually
true
for bitstream formats like MPEG. It's just the size of the buffer used to store
the
bitstream, i.e. one buffer may actually contain multiple compressed images, or a
compressed image is split over multiple buffers.
Only for MJPEG is this statement true since each buffer will contain a single
compressed JPEG image.
Regards,
Hans
