diff options
| -rw-r--r-- | Documentation/media/uapi/v4l/pixfmt-v4l2-mplane.rst | 15 | ||||
| -rw-r--r-- | Documentation/media/uapi/v4l/pixfmt-v4l2.rst | 13 |
2 files changed, 26 insertions, 2 deletions
diff --git a/Documentation/media/uapi/v4l/pixfmt-v4l2-mplane.rst b/Documentation/media/uapi/v4l/pixfmt-v4l2-mplane.rst index 5688c816e334..db43dda5aafb 100644 --- a/Documentation/media/uapi/v4l/pixfmt-v4l2-mplane.rst +++ b/Documentation/media/uapi/v4l/pixfmt-v4l2-mplane.rst @@ -31,7 +31,20 @@ 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 number of bytes required by the + codec to support the worst-case compression scenario. + + The driver will set the value for uncompressed images. + + Clients are allowed to set the sizeimage field for variable length + compressed data flagged with ``V4L2_FMT_FLAG_COMPRESSED`` at + :ref:`VIDIOC_ENUM_FMT`, but the driver may ignore it and set the + value itself, or it may modify the provided value based on + alignment requirements or minimum/maximum size requirements. + If the client wants to leave this to the driver, then it should + set sizeimage to 0. * - __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..da6da2ef139a 100644 --- a/Documentation/media/uapi/v4l/pixfmt-v4l2.rst +++ b/Documentation/media/uapi/v4l/pixfmt-v4l2.rst @@ -89,7 +89,18 @@ 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. + number of bytes required by the codec to support the worst-case + compression scenario. + + The driver will set the value for uncompressed images. + + Clients are allowed to set the sizeimage field for variable length + compressed data flagged with ``V4L2_FMT_FLAG_COMPRESSED`` at + :ref:`VIDIOC_ENUM_FMT`, but the driver may ignore it and set the + value itself, or it may modify the provided value based on + alignment requirements or minimum/maximum size requirements. + If the client wants to leave this to the driver, then it should + set sizeimage to 0. * - __u32 - ``colorspace`` - Image colorspace, from enum :c:type:`v4l2_colorspace`. |