diff options
Diffstat (limited to 'Documentation')
| -rw-r--r-- | Documentation/DocBook/media/v4l/io.xml | 14 |
1 files changed, 14 insertions, 0 deletions
diff --git a/Documentation/DocBook/media/v4l/io.xml b/Documentation/DocBook/media/v4l/io.xml index 1e7ea3c2e2ad..49e48be9c2b4 100644 --- a/Documentation/DocBook/media/v4l/io.xml +++ b/Documentation/DocBook/media/v4l/io.xml @@ -653,6 +653,20 @@ plane, are stored in struct <structname>v4l2_plane</structname> instead. In that case, struct <structname>v4l2_buffer</structname> contains an array of plane structures.</para> + <para>Dequeued video buffers come with timestamps. The driver + decides at which part of the frame and with which clock the + timestamp is taken. Please see flags in the masks + <constant>V4L2_BUF_FLAG_TIMESTAMP_MASK</constant> and + <constant>V4L2_BUF_FLAG_TSTAMP_SRC_MASK</constant> in <xref + linkend="buffer-flags" />. These flags are always valid and constant + across all buffers during the whole video stream. Changes in these + flags may take place as a side effect of &VIDIOC-S-INPUT; or + &VIDIOC-S-OUTPUT; however. The + <constant>V4L2_BUF_FLAG_TIMESTAMP_COPY</constant> timestamp type + which is used by e.g. on mem-to-mem devices is an exception to the + rule: the timestamp source flags are copied from the OUTPUT video + buffer to the CAPTURE video buffer.</para> + <table frame="none" pgwide="1" id="v4l2-buffer"> <title>struct <structname>v4l2_buffer</structname></title> <tgroup cols="4"> |