clocking help

Kapil Agrawal kapil.agl at
Thu Mar 24 07:04:56 PDT 2011

Hello Steve,

I think the best way would be not use a system clock but rather have an
internal clock of your src element, which can use values from driver.

Hope this will help ?


On Thu, Mar 24, 2011 at 2:33 AM, Steve Roskowski <rosko at>wrote:

> I am building a gstreamer camera source.  It sits directly on top of
> the raw hardware and takes advantage of various system oddities.  It
> generates 3 srcs - an encoded video stream, a occasional high
> resolution snapshot (based on request), and a low resolution preview
> data stream.  I want all of them tagged with real-time timestamps
> (that is the actual day/date/time from the system), but accurate to
> the fractional second of the frame generation.
> I cannot figure out the approved way to do this.  The implementations
> I have found, (v4l2 for example), simply use the system clock and
> attach a timestamp as the buffer is generated at the user level.  This
> fails badly in a loaded embedded device - the variance in thread
> servicing shows up in the timestamping, resulting in jerky video.
> I have accurate timestamps attached to the buffers coming up from the
> drivers.  How can I take advantage of this?  The simplistic answer of
> directly converting this into timestamps on each buffer works fine for
> a single src, but with multiple src-s the pipeline fails to get out of
> pre-roll.
> I am based on top of base_src which is driving the video stream src,
> and sample queues for each of the lower speed sources in the create
> function, pushing buffers if they are there.
> any help would be appreciated...
> --
> Steve
> _______________________________________________
> gstreamer-embedded mailing list
> gstreamer-embedded at

-- (Gstreamer, ffmpeg, Red5, Streaming)
twitter handle: @gst_kaps
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