On 1/21/19 11:48 AM, Stanimir Varbanov wrote: > Hi Hans, > > On 1/18/19 11:13 AM, Hans Verkuil wrote: >> 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 <stanimir.varbanov@xxxxxxxxxx> >>> --- >>> 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. >> > > Do you want me to change something in the current documentation, i.e. > the quoted above? Hmm, it looks like this discussion stalled (i.e. I forgot to reply). How about this: "When the image consists of variable length compressed data this is the number of bytes required by the encoder to support the worst-case compression scenario. Clients are allowed to set this field. However, drivers may ignore the value or modify it." Regards, Hans > >> Only for MJPEG is this statement true since each buffer will contain a single >> compressed JPEG image. >> >> Regards, >> >> Hans >> >
