From 9ca8dbcc65cfc63d6f5ef3312a33184e1d726e00 Mon Sep 17 00:00:00 2001 From: Yunhong Jiang Date: Tue, 4 Aug 2015 12:17:53 -0700 Subject: Add the rt linux 4.1.3-rt3 as base Import the rt linux 4.1.3-rt3 as OPNFV kvm base. It's from git://git.kernel.org/pub/scm/linux/kernel/git/rt/linux-rt-devel.git linux-4.1.y-rt and the base is: commit 0917f823c59692d751951bf5ea699a2d1e2f26a2 Author: Sebastian Andrzej Siewior Date: Sat Jul 25 12:13:34 2015 +0200 Prepare v4.1.3-rt3 Signed-off-by: Sebastian Andrzej Siewior We lose all the git history this way and it's not good. We should apply another opnfv project repo in future. Change-Id: I87543d81c9df70d99c5001fbdf646b202c19f423 Signed-off-by: Yunhong Jiang --- .../Documentation/DocBook/media/v4l/dev-codec.xml | 27 ++++++++++++++++++++++ 1 file changed, 27 insertions(+) create mode 100644 kernel/Documentation/DocBook/media/v4l/dev-codec.xml (limited to 'kernel/Documentation/DocBook/media/v4l/dev-codec.xml') diff --git a/kernel/Documentation/DocBook/media/v4l/dev-codec.xml b/kernel/Documentation/DocBook/media/v4l/dev-codec.xml new file mode 100644 index 000000000..ff44c16fc --- /dev/null +++ b/kernel/Documentation/DocBook/media/v4l/dev-codec.xml @@ -0,0 +1,27 @@ + 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 &VIDIOC-STREAMON; for both capture and output +to start the codec. + + 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 . + + 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). -- cgit 1.2.3-korg