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Diffstat (limited to 'Documentation/DocBook/media/v4l/dev-codec.xml')
| -rw-r--r-- | Documentation/DocBook/media/v4l/dev-codec.xml | 27 |
1 files changed, 0 insertions, 27 deletions
diff --git a/Documentation/DocBook/media/v4l/dev-codec.xml b/Documentation/DocBook/media/v4l/dev-codec.xml deleted file mode 100644 index ff44c16fc080..000000000000 --- a/Documentation/DocBook/media/v4l/dev-codec.xml +++ /dev/null @@ -1,27 +0,0 @@ - <title>Codec Interface</title> - - <para>A V4L2 codec can compress, decompress, transform, or otherwise -convert video data from one format into another format, in memory. Typically -such devices are memory-to-memory devices (i.e. devices with the -<constant>V4L2_CAP_VIDEO_M2M</constant> or <constant>V4L2_CAP_VIDEO_M2M_MPLANE</constant> -capability set). -</para> - - <para>A memory-to-memory video node acts just like a normal video node, but it -supports both output (sending frames from memory to the codec hardware) and -capture (receiving the processed frames from the codec hardware into memory) -stream I/O. An application will have to setup the stream -I/O for both sides and finally call &VIDIOC-STREAMON; for both capture and output -to start the codec.</para> - - <para>Video compression codecs use the MPEG controls to setup their codec parameters -(note that the MPEG controls actually support many more codecs than just MPEG). -See <xref linkend="mpeg-controls"></xref>.</para> - - <para>Memory-to-memory devices can often be used as a shared resource: you can -open the video node multiple times, each application setting up their own codec properties -that are local to the file handle, and each can use it independently from the others. -The driver will arbitrate access to the codec and reprogram it whenever another file -handler gets access. This is different from the usual video node behavior where the video properties -are global to the device (i.e. changing something through one file handle is visible -through another file handle).</para> |