appsrc: minimum latency bigger than maximum latency

[Milian Wolff]

On Mittwoch, 27. November 2019 10:58:52 CET Tim Müller wrote:
> On Tue, 2019-11-26 at 13:09 +0100, Milian Wolff wrote:
> 
> Hi Milian,
> 
> > 0:00:01.316311614  1043 0x7300fe60 ERROR               GST_PADS
> > gstpad.c:
> > 3352:gst_pad_query_latency_default:<mixer:src> minimum latency bigger
> > than
> > maximum latency
> > 0:00:01.316615832  1043 0x7300fe60 WARN              aggregator
> > gstaggregator.c:1783:gst_aggregator_query_latency_unlocked:<mixer>
> > warning:
> > Impossible to configure latency: max 0:00:00.000000000 < min
> > 0:00:00.040000000. Add queues or other buffering elements.
> > 
> > How do I solve this?
> 
> This usually means there is not enough buffering in one part of the
> pipeline to cater for the worst case latency config that might happen
> in another part of the pipeline. To solve this, add a "queue max-size-
> bytes=0 max-size-buffers=0" in the other branch.

Indeed, that removes the warning - thanks! 

> Problem here is perhaps that you put appsrc into live mode but didn't
> configure latency settings on appsrc? In any case, a queue might help
> here. It will provide buffering. It won't introduce latency/delay
> itself.

Yes - that's probably the issue. I tried adding explicit latenc values but 
that didn't help. Quite frankly, the documentation on that topic is quasi 
impossible to understand for me. GstAppSrc just references latency but doesn't 
explain when one should use it and what values one should use. Then the 
overall topic on Latency just talks about the time between two points which is 
a metric I can understand - but how does one apply this concept to a single 
point (AppSrc)? If my AppSrc is fed with a 25Hz timer, is the max-latency then 
40ms?

Thanks

-- 
Milian Wolff | milian.wolff at kdab.com | Senior Software Engineer
KDAB (Deutschland) GmbH, a KDAB Group company
Tel: +49-30-521325470
KDAB - The Qt, C++ and OpenGL Experts
-------------- next part --------------
A non-text attachment was scrubbed...
Name: smime.p7s
Type: application/pkcs7-signature
Size: 3826 bytes
Desc: not available
URL: <https://lists.freedesktop.org/archives/gstreamer-devel/attachments/20191127/6698de25/attachment.bin>