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| author | Umang Jain <umang.jain@ideasonboard.com> | 2022-03-17 16:17:39 +0530 |
|---|---|---|
| committer | Umang Jain <umang.jain@ideasonboard.com> | 2022-03-23 21:52:57 +0530 |
| commit | b24e39be48ffa581ef93044084bc3b4d20053804 (patch) | |
| tree | 3ad484db5fabd8fb325027e37f0dcb43c520825c | |
| parent | ea9bc717bd0988f481956178fd0c399998b016f7 (diff) | |
libcamera: v4l2_videodevice: Clarify setting of v4l2_buffer timestamp
Add a comment to clarify why we set v4l2_buffer timestamp while
queuing the buffer (VIDIOC_QBUF). The timstamps are required to
be supplied for memory-to-memory devices for output streams which
then are copied to capture stream buffers with the help of
V4L2_BUF_FLAG_TIMESTAMP_COPY (set by the driver).
Signed-off-by: Umang Jain <umang.jain@ideasonboard.com>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Kieran Bingham <kieran.bingham@ideasonboard.com>
| -rw-r--r-- | src/libcamera/v4l2_videodevice.cpp | 8 |
1 files changed, 8 insertions, 0 deletions
diff --git a/src/libcamera/v4l2_videodevice.cpp b/src/libcamera/v4l2_videodevice.cpp index 5580269f..95b9c38b 100644 --- a/src/libcamera/v4l2_videodevice.cpp +++ b/src/libcamera/v4l2_videodevice.cpp @@ -1600,6 +1600,14 @@ int V4L2VideoDevice::queueBuffer(FrameBuffer *buffer) buf.length = planes[0].length; } + /* + * Timestamps are to be supplied if the device is a mem-to-mem + * device. The drivers will have V4L2_BUF_FLAG_TIMESTAMP_COPY + * set hence these timestamps will be copied from the output + * buffers to capture buffers. If the device is not mem-to-mem, + * there is no harm in setting the timestamps as they will be + * ignored (and over-written). + */ buf.timestamp.tv_sec = metadata.timestamp / 1000000000; buf.timestamp.tv_usec = (metadata.timestamp / 1000) % 1000000; } |