Splitting source to measure latency
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Splitting source to measure latency
 
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Hello,
I want to split the video source to measure the latency between a video generated and displayed on a local and remote display using: # gst-launch-1.0 -v videotestsrc \ ! video/xraw,format=RGBx,width=800,height=600,framerate=30/1 \ ! timeoverlay ! tee name=t \ t. ! queue ! kmssink t. ! queue ! vaapipostproc ! vaapijpegenc quality=90 \ ! rtpjpegpay ! udpsink host=192.168.0.254 port=50004 I'm interested in the latency due to: vaapipostproc ! vaapijpegenc quality=90 ! rtpjpegpay \ ! udpsink host=192.168.0.254 port=50004 Then I take a picture of both, the local and the remote display. I see that the time of the video on the remote side is delayed by more or less exactly *one* second. How does the "tee" deliver the packages to both streams? One by one? Is it possible at all to measure the latency using "tee"? Have I missed something else? Wolfgang. _______________________________________________ gstreamer-devel mailing list [hidden email] https://lists.freedesktop.org/mailman/listinfo/gstreamer-devel |
Re: Splitting source to measure latency
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On Tue, May 29, 2018 at 12:27:00PM +0200, Wolfgang Grandegger wrote:
> Hello, > > I want to split the video source to measure the latency between a video > generated and displayed on a local and remote display using: > > # gst-launch-1.0 -v videotestsrc \ > ! video/xraw,format=RGBx,width=800,height=600,framerate=30/1 \ > ! timeoverlay ! tee name=t \ > t. ! queue ! kmssink > t. ! queue ! vaapipostproc ! vaapijpegenc quality=90 \ > ! rtpjpegpay ! udpsink host=192.168.0.254 port=50004 > > I'm interested in the latency due to: > > vaapipostproc ! vaapijpegenc quality=90 ! rtpjpegpay \ > ! udpsink host=192.168.0.254 port=50004 > > Then I take a picture of both, the local and the remote display. I see > that the time of the video on the remote side is delayed by more or less > exactly *one* second. How does the "tee" deliver the packages to both > streams? One by one? Is it possible at all to measure the latency using > "tee"? Have I missed something else? I'm only new here, but does your exactly one second change if you give each queue a max-size-time other than the default of one second? Could you examine current-level-time of each queue? -- James Cameron http://quozl.netrek.org/ _______________________________________________ gstreamer-devel mailing list [hidden email] https://lists.freedesktop.org/mailman/listinfo/gstreamer-devel |
Re: Splitting source to measure latency
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In reply to this post by Wolfgang Grandegger
Le mardi 29 mai 2018 à 12:27 +0200, Wolfgang Grandegger a écrit :
> I want to split the video source to measure the latency between a video > generated and displayed on a local and remote display using: > > # gst-launch-1.0 -v videotestsrc \ > ! video/xraw,format=RGBx,width=800,height=600,framerate=30/1 \ > ! timeoverlay ! tee name=t \ > t. ! queue ! kmssink > t. ! queue ! vaapipostproc ! vaapijpegenc quality=90 \ > ! rtpjpegpay ! udpsink host=192.168.0.254 port=50004 > > I'm interested in the latency due to: > > vaapipostproc ! vaapijpegenc quality=90 ! rtpjpegpay \ > ! udpsink host=192.168.0.254 port=50004 > > Then I take a picture of both, the local and the remote display. I see > that the time of the video on the remote side is delayed by more or less > exactly *one* second. How does the "tee" deliver the packages to both > streams? One by one? Is it possible at all to measure the latency using > "tee"? Have I missed something else? tee is synchronous and single threaded, that's why you need queue afterward. Though, it should not introduce a large delay like y uhave described. I'd look at your receiver side for delays. Nicolas _______________________________________________ gstreamer-devel mailing list [hidden email] https://lists.freedesktop.org/mailman/listinfo/gstreamer-devel |
Re: Splitting source to measure latency
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In reply to this post by James Cameron
Hello,
Am 29.05.2018 um 12:43 schrieb James Cameron: > On Tue, May 29, 2018 at 12:27:00PM +0200, Wolfgang Grandegger wrote: >> Hello, >> >> I want to split the video source to measure the latency between a video >> generated and displayed on a local and remote display using: >> >> # gst-launch-1.0 -v videotestsrc \ >> ! video/xraw,format=RGBx,width=800,height=600,framerate=30/1 \ >> ! timeoverlay ! tee name=t \ >> t. ! queue ! kmssink >> t. ! queue ! vaapipostproc ! vaapijpegenc quality=90 \ >> ! rtpjpegpay ! udpsink host=192.168.0.254 port=50004 >> >> I'm interested in the latency due to: >> >> vaapipostproc ! vaapijpegenc quality=90 ! rtpjpegpay \ >> ! udpsink host=192.168.0.254 port=50004 >> >> Then I take a picture of both, the local and the remote display. I see >> that the time of the video on the remote side is delayed by more or less >> exactly *one* second. How does the "tee" deliver the packages to both >> streams? One by one? Is it possible at all to measure the latency using >> "tee"? Have I missed something else? > > I'm only new here, but does your exactly one second change if you > give each queue a max-size-time other than the default of one second? > > Could you examine current-level-time of each queue? Setting "max-size-time" to 0 didn't help. My problem was on the receiver side, as pointed out by Nicolas. With VLC settings from [1] I was able to reduce the latency below 100ms. [1] https://www.slac.stanford.edu/grp/cd/soft/unix/VLC-setup.html Wolfgang. _______________________________________________ gstreamer-devel mailing list [hidden email] https://lists.freedesktop.org/mailman/listinfo/gstreamer-devel |
Re: Splitting source to measure latency
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In reply to this post by Nicolas Dufresne-5
Hello Nicolas,
I readded the ML to the CC... Am 29.05.2018 um 15:31 schrieb Nicolas Dufresne: > Le mardi 29 mai 2018 à 15:11 +0200, Wolfgang Grandegger a écrit : >> Hello Nicolas, >> >> Am 29.05.2018 um 14:14 schrieb Wolfgang Grandegger: >>> Hello, >>> >>> Am 29.05.2018 um 13:12 schrieb Nicolas Dufresne: >>>> Le mardi 29 mai 2018 à 12:27 +0200, Wolfgang Grandegger a écrit : >>>>> I want to split the video source to measure the latency between a video >>>>> generated and displayed on a local and remote display using: >>>>> >>>>> # gst-launch-1.0 -v videotestsrc \ >>>>> ! video/xraw,format=RGBx,width=800,height=600,framerate=30/1 \ >>>>> ! timeoverlay ! tee name=t \ >>>>> t. ! queue ! kmssink >>>>> t. ! queue ! vaapipostproc ! vaapijpegenc quality=90 \ >>>>> ! rtpjpegpay ! udpsink host=192.168.0.254 port=50004 >>>>> >>>>> I'm interested in the latency due to: >>>>> >>>>> vaapipostproc ! vaapijpegenc quality=90 ! rtpjpegpay \ >>>>> ! udpsink host=192.168.0.254 port=50004 >>>>> >>>>> Then I take a picture of both, the local and the remote display. I see >>>>> that the time of the video on the remote side is delayed by more or less >>>>> exactly *one* second. How does the "tee" deliver the packages to both >>>>> streams? One by one? Is it possible at all to measure the latency using >>>>> "tee"? Have I missed something else? >>>> >>>> tee is synchronous and single threaded, that's why you need queue >>>> afterward. Though, it should not introduce a large delay like y uhave >>>> described. I'd look at your receiver side for delays. >>> >>> Thanks for you hint... I'm using VLC on the receiver side using a >>> default network cache of 1 second. With settings describe in [1] I was >>> able to reduce the latency below 100ms. >> >> Sometimes the time delay between on the picture is even less than 50ms. >> Is that realistic? What can I expect? OK, "kmssink" also introduces some >> latency. > > Display drivers will introduce some latency, but it's variable, because > the display refresh is not synchronized with the stream rate. So let's > assumes 60 fps, which means a bit more then 16ms, times two, kmssink > and VLC, you already have a plausible variation of 32ms. Then another > aspect, vlc implement a adaptive jitterbuffer, which mean it will > increase the delay is there is too much jitter. > > If you try with a gstreamer receiver, you should be able to test even > lower latency on local network. That makes sense and does confirm what I measure. The delay between both times various between 0 and 3x16ms. So far I didn't use GStreamer because I'm still at Ubuntu 14.04. Will switch to my PC with 16.04. Thanks, Wolfgang. _______________________________________________ gstreamer-devel mailing list [hidden email] https://lists.freedesktop.org/mailman/listinfo/gstreamer-devel |
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