From bfd0306462fdbc5e0a8c6999aef9dde0f9745399 Mon Sep 17 00:00:00 2001 From: Sakari Ailus Date: Fri, 7 Feb 2014 19:44:39 -0300 Subject: [media] v4l: Document timestamp buffer flag behaviour Timestamp buffer flags are constant at the moment. Document them so that 1) they're always valid and 2) not changed by the drivers. This leaves room to extend the functionality later on if needed. Signed-off-by: Sakari Ailus Acked-by: Hans Verkuil Signed-off-by: Mauro Carvalho Chehab --- Documentation/DocBook/media/v4l/io.xml | 14 ++++++++++++++ 1 file changed, 14 insertions(+) (limited to 'Documentation/DocBook/media') 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 v4l2_plane instead. In that case, struct v4l2_buffer contains an array of plane structures. + 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 + V4L2_BUF_FLAG_TIMESTAMP_MASK and + V4L2_BUF_FLAG_TSTAMP_SRC_MASK in . 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 + V4L2_BUF_FLAG_TIMESTAMP_COPY 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. + struct <structname>v4l2_buffer</structname> -- cgit v1.2.3