diff options
Diffstat (limited to 'Documentation/media/uapi/v4l/dev-codec.rst')
| -rw-r--r-- | Documentation/media/uapi/v4l/dev-codec.rst | 43 |
1 files changed, 0 insertions, 43 deletions
diff --git a/Documentation/media/uapi/v4l/dev-codec.rst b/Documentation/media/uapi/v4l/dev-codec.rst deleted file mode 100644 index b5e017c17834..000000000000 --- a/Documentation/media/uapi/v4l/dev-codec.rst +++ /dev/null @@ -1,43 +0,0 @@ -.. Permission is granted to copy, distribute and/or modify this -.. document under the terms of the GNU Free Documentation License, -.. Version 1.1 or any later version published by the Free Software -.. Foundation, with no Invariant Sections, no Front-Cover Texts -.. and no Back-Cover Texts. A copy of the license is included at -.. Documentation/media/uapi/fdl-appendix.rst. -.. -.. TODO: replace it to GFDL-1.1-or-later WITH no-invariant-sections - -.. _codec: - -*************** -Codec Interface -*************** - -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 -``V4L2_CAP_VIDEO_M2M`` or ``V4L2_CAP_VIDEO_M2M_MPLANE`` capability set). - -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 :ref:`VIDIOC_STREAMON <VIDIOC_STREAMON>` -for both capture and output to start the codec. - -Video compression codecs use the MPEG controls to setup their codec -parameters - -.. note:: - - The MPEG controls actually support many more codecs than - just MPEG. See :ref:`mpeg-controls`. - -Memory-to-memory devices function 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). |