diff options
author | Thomas Gleixner <tglx@linutronix.de> | 2013-07-04 23:11:22 +0200 |
---|---|---|
committer | Thomas Gleixner <tglx@linutronix.de> | 2013-07-04 23:11:22 +0200 |
commit | 2b0f89317e99735bbf32eaede81f707f98ab1b5e (patch) | |
tree | 16daa236e21876b11f1c0b9256cd4046aadba020 /Documentation/DocBook | |
parent | 07bd1172902e782f288e4d44b1fde7dec0f08b6f (diff) | |
parent | fa18f7bde3ad4568d1d343b60d963bfbd8dc3991 (diff) |
Merge branch 'timers/posix-cpu-timers-for-tglx' of
git://git.kernel.org/pub/scm/linux/kernel/git/frederic/linux-dynticks into timers/core
Frederic sayed: "Most of these patches have been hanging around for
several month now, in -mmotm for a significant chunk. They already
missed a few releases."
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Diffstat (limited to 'Documentation/DocBook')
-rw-r--r-- | Documentation/DocBook/media/v4l/dev-codec.xml | 35 | ||||
-rw-r--r-- | Documentation/DocBook/media/v4l/v4l2.xml | 2 |
2 files changed, 23 insertions, 14 deletions
diff --git a/Documentation/DocBook/media/v4l/dev-codec.xml b/Documentation/DocBook/media/v4l/dev-codec.xml index dca0ecd54dc6..ff44c16fc080 100644 --- a/Documentation/DocBook/media/v4l/dev-codec.xml +++ b/Documentation/DocBook/media/v4l/dev-codec.xml @@ -1,18 +1,27 @@ <title>Codec Interface</title> - <note> - <title>Suspended</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>This interface has been be suspended from the V4L2 API -implemented in Linux 2.6 until we have more experience with codec -device interfaces.</para> - </note> + <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>A V4L2 codec can compress, decompress, transform, or otherwise -convert video data from one format into another format, in memory. -Applications send data to be converted to the driver through a -&func-write; call, and receive the converted data through a -&func-read; call. For efficiency a driver may also support streaming -I/O.</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>[to do]</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> diff --git a/Documentation/DocBook/media/v4l/v4l2.xml b/Documentation/DocBook/media/v4l/v4l2.xml index bfc93cdcf696..bfe823dd0f31 100644 --- a/Documentation/DocBook/media/v4l/v4l2.xml +++ b/Documentation/DocBook/media/v4l/v4l2.xml @@ -493,7 +493,7 @@ and discussions on the V4L mailing list.</revremark> </partinfo> <title>Video for Linux Two API Specification</title> - <subtitle>Revision 3.9</subtitle> + <subtitle>Revision 3.10</subtitle> <chapter id="common"> &sub-common; |