AW: [External] Re: Streaming freezes (vaapi or v4l2src)

Timtchenko, Michael Michael.Timtchenko at agcocorp.com
Tue Jul 28 12:20:26 UTC 2020


Hi all,

sorry 4 my late response. I had a lot of work during the last two weeks.

I want to thank Nicolas and Victor for fast response and very good input!

I fixed the issue by using a rtpjitterbuffer in combination with the low-latency flag. Without the rtpjitterbuffer the image is getting teared. So I guess it’s necessary in this case.

The following pipeline works quite well in my case:

gst-launch-1.0 udpsrc port=55555 caps="application/x-rtp,media=(string)video,clock-rate=(int)90000, encoding-name=(string)H264, payload=(int)96" ! rtpjitterbuffer latency=10 ! rtph264depay ! vaapih264dec low-latency=true ! vaapipostproc ! kmssink

Timestamping the sink did not improve the misbehavior.

Best regards,
Michael



Von: gstreamer-devel [mailto:gstreamer-devel-bounces at lists.freedesktop.org] Im Auftrag von Nicolas Dufresne
Gesendet: Donnerstag, 16. Juli 2020 14:33
An: Discussion of the development of and with GStreamer <gstreamer-devel at lists.freedesktop.org>
Betreff: [External] Re: Streaming freezes (vaapi or v4l2src)


Le jeu. 16 juill. 2020 04 h 00, Timtchenko, Michael <Michael.Timtchenko at agcocorp.com<mailto:Michael.Timtchenko at agcocorp.com>> a écrit :
Hello guys,

i’ve encountered a very strange behavior while streaming from a v4l2src to a kmssink (or glimagesink) by using vaapi-components for decoding. The problem is, that the streaming starts for 2 seconds, then freezes for 2 seconds and continues again for 2 seconds and so on. This effect is only noticeable when using vaapi-components. If I use a pipeline with simply software decoding, the stream is displayed fluently.
Two seconds could be the key frame distance ?



My sending pipeline is constructed as follows:

gst-launch-1.0 v4l2src io-mode=dmabuf device=/dev/video$(($1+4)) ! video/x-raw,format=YV12,width=720,height=576  ! v4l2h264enc ! rtph264pay ! udpsink host=${IP} port=55555
v4l2h264enc has this extra-controls property that let you genetically change he specific configuration, just an information.



Setting pipeline to PAUSED ...
Pipeline is live and does not need PREROLL ...
Setting pipeline to PLAYING ...
New clock: GstSystemClock
Redistribute latency...

The erroneous reading pipeline looks like this:

gst-launch-1.0 udpsrc port=55555 caps="application/x-rtp,media=(string)video,clock-rate=(int)90000, encoding-name=(string)H264, payload=(int)96" ! rtph264depay ! vaapih264dec ! vaapipostproc width=720 height=576 ! glimagesink

One thing to note is the absence of rtpjitterbuffer element, which would allow adding some latency to remove network jitter. So that is one thing to try.

Another possibility is that the issue is cause by vaaph264dec having more latency then avdec_h264. Perhaps give the low-latency property a try ?

Let's hope one of these suggestions helps.


Setting pipeline to PAUSED ...
Pipeline is live and does not need PREROLL ...
Got context from element 'vaapipostproc0': gst.vaapi.Display=context, gst.vaapi.Display=(GstVaapiDisplay)"\(GstVaapiDisplayDRM\)\ vaapidisplaydrm1";
Setting pipeline to PLAYING ...
New clock: GstSystemClock
Redistribute latency...
WARNING: from element /GstPipeline:pipeline0/GstKMSSink:kmssink0: A lot of buffers are being dropped.
Additional debug info:
../libs/gst/base/gstbasesink.c(3005): gst_base_sink_is_too_late (): /GstPipeline:pipeline0/GstKMSSink:kmssink0:
There may be a timestamping problem, or this computer is too slow.
WARNING: from element /GstPipeline:pipeline0/GstKMSSink:kmssink0: A lot of buffers are being dropped.
Additional debug info:
../libs/gst/base/gstbasesink.c(3005): gst_base_sink_is_too_late (): /GstPipeline:pipeline0/GstKMSSink:kmssink0:
There may be a timestamping problem, or this computer is too slow.

If I run the following pipeline on the same system, the stream is presented fluently without any problems:

gst-launch-1. 0 udpsrc port=55555 caps=\"application/x-rtp, media=(string)video, clock-rate=(int)90000, encoding-name=(string)H264, payload=(int)96\" ! rtph264depay ! avdec_h264 ! decodebin ! videoconvert ! kmssink

I’m not sure what exactly the problem is. Maybe the timestamping mechanism in vaapi has a different behavior then in the avdec_h264 as the log message says?  I’ve also changed log levels but I couldn’t find anything helpful.

Any help for further diagnostics is highly appreciated.

Kind regards
Michael





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