diff options
Diffstat (limited to 'Documentation/DocBook/media/v4l/io.xml')
| -rw-r--r-- | Documentation/DocBook/media/v4l/io.xml | 9 |
1 files changed, 7 insertions, 2 deletions
diff --git a/Documentation/DocBook/media/v4l/io.xml b/Documentation/DocBook/media/v4l/io.xml index a086a5db7a18..e5e8325aa3d7 100644 --- a/Documentation/DocBook/media/v4l/io.xml +++ b/Documentation/DocBook/media/v4l/io.xml @@ -870,7 +870,8 @@ should set this to 0.</entry> If the application sets this to 0 for an output stream, then <structfield>bytesused</structfield> will be set to the size of the plane (see the <structfield>length</structfield> field of this struct) - by the driver.</entry> + by the driver. Note that the actual image data starts at + <structfield>data_offset</structfield> which may not be 0.</entry> </row> <row> <entry>__u32</entry> @@ -919,6 +920,10 @@ should set this to 0.</entry> <entry>Offset in bytes to video data in the plane. Drivers must set this field when <structfield>type</structfield> refers to an input stream, applications when it refers to an output stream. + Note that data_offset is included in <structfield>bytesused</structfield>. + So the size of the image in the plane is + <structfield>bytesused</structfield>-<structfield>data_offset</structfield> at + offset <structfield>data_offset</structfield> from the start of the plane. </entry> </row> <row> @@ -1066,7 +1071,7 @@ state, in the application domain so to say.</entry> <entry>Drivers set or clear this flag when calling the <constant>VIDIOC_DQBUF</constant> ioctl. It may be set by video capture devices when the buffer contains a compressed image which is a -key frame (or field), &ie; can be decompressed on its own. Also know as +key frame (or field), &ie; can be decompressed on its own. Also known as an I-frame. Applications can set this bit when <structfield>type</structfield> refers to an output stream.</entry> </row> |