diff options
author | Mauro Carvalho Chehab <mchehab@redhat.com> | 2013-06-20 05:19:09 -0300 |
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committer | Mauro Carvalho Chehab <mchehab@redhat.com> | 2013-06-20 05:19:09 -0300 |
commit | 37c1d2e4098e48d9107858246027510efcfd7774 (patch) | |
tree | fd676992f6b27f2576420bbc7b25028d05125940 /Documentation/DocBook | |
parent | 414abbd2cd4c2618895f02ed3a76ec6647281436 (diff) | |
parent | aad760136537fdfa10e5ac76bd3c79bde2100863 (diff) |
Merge branch 'linus' into patchwork
* linus: (1465 commits)
ARM: tegra30: clocks: Fix pciex clock registration
lseek(fd, n, SEEK_END) does *not* go to eof - n
Linux 3.10-rc6
smp.h: Use local_irq_{save,restore}() in !SMP version of on_each_cpu().
powerpc: Fix missing/delayed calls to irq_work
powerpc: Fix emulation of illegal instructions on PowerNV platform
powerpc: Fix stack overflow crash in resume_kernel when ftracing
snd_pcm_link(): fix a leak...
use can_lookup() instead of direct checks of ->i_op->lookup
move exit_task_namespaces() outside of exit_notify()
fput: task_work_add() can fail if the caller has passed exit_task_work()
xfs: don't shutdown log recovery on validation errors
xfs: ensure btree root split sets blkno correctly
xfs: fix implicit padding in directory and attr CRC formats
xfs: don't emit v5 superblock warnings on write
mei: me: clear interrupts on the resume path
mei: nfc: fix nfc device freeing
mei: init: Flush scheduled work before resetting the device
sctp: fully initialize sctp_outq in sctp_outq_init
netiucv: Hold rtnl between name allocation and device registration.
...
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 dca0ecd54dc..ff44c16fc08 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 bfc93cdcf69..bfe823dd0f3 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; |