DeckLink source

Josh Doe josh at
Thu Jun 30 08:43:08 PDT 2011

Setting sync=false on either d3dvideosink or dshowvideosink seems to make
things work alright, so it seems to be a timestamping/clocking problem. I've
checked the timestamps with identity, and they appear correct (monotonically
increasing from 0 with 33ms steps). I am getting a warning "Failed to
configure latency of 0:00:00.0000000" from gst_bin_do_latency_func(),
however I don't see how that could be related to my particular problem,
other than indicating there's a clock problem. Help is appreciated!

On Wed, Jun 29, 2011 at 1:32 PM, Josh Doe <josh at> wrote:

> I've managed to get it working using glimagesink, however it still performs
> horribly with dshowvideosink. Instead of setting the buffer flag to
> GST_BUFFER_FLAG_DISCONT for the first frame (decklinksrc->num_frames==0), I
> pushed a gst_event_new_newsegment(). Also I set GST_BUFFER_OFFSET_END to
> match OFFSET (though I don't think this matters). The timestamps and
> duration all seem to be set correctly, so I'm not sure what else could be
> the problem, dshowvideosink works just fine with videotestsrc.
> -Josh
> On Mon, Jun 27, 2011 at 1:20 PM, Josh Doe <josh at> wrote:
>> I'm working on making decklinksrc work on Windows, and can stream to disk
>> fine (at normal framerates, using composite NTSC source), but if i display
>> to the screen (e.g. using dshowvideosink) the framerate drops to something
>> like 1fps.
>> What might be the cause of this?
>> FYI, DeckLink provides a COM interface, and I've copied the relevant bits
>> from dshowvideosink for handling this.
>> Thanks,
> -Josh
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