How to reduce the lag in WebM/VP8 stream

[Tiến Nguyễn]

Hi there,

Forgive me if this newbie question has been asked already, in that case please give me a ref link to the answer :).

I have a video server set up (I could use either GStreamer or ffmeg)  to send out a live camera feed in HTTP WebM/VP8 on an HTML5 page using <video> tag. It's all working great except for the lag is huge; about 5 to 6 seconds. What would be the best encoding parameters and receiver parameters (if there is any) to achieve a less than 500ms lag?

Thanks, 

[bryand...@gmail.com]

There is no way to limit the buffering done by the VIDEO and AUDIO tags when streaming over HTTP.

If you make your server a WebRTC MCU you could get the results that you want by playing back the WebRTC media stream in the video element.

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[Silvia Pfeiffer]

Do you know if your delay is introduced server or client side? I suspect much of it is server side, so you should optimise that first.

Best Regards,
Silvia.

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[Tiến Nguyễn]

I have a suspicion that it could be (some) on the server side because I also use the VLC command line with a very small amount of network caching as a client to display the stream as http://IP:PORT/ and the VLC also show a lag.

I have search all over and there is no tutorial or example of any real time set up for VP8/WebM so I hope this group could give me some pointer of where to start.

Here is a options that I set for my Gstreamer vp8enc plugin:

vp8enc end-usage=cbr cpu-used=5 threads=4 qc-level=30 target-bitrate=2048 max-quantizer=40 min-quantizer=10

My understanding is by default, the encoder will do single pass compression.

[Silvia Pfeiffer]

The best way to get the delay down is - as Bryan says - to get a
WebRTC component on the server to stream your video to a WebRTC client
e.g. in your (Chrome or Firefox) Web browser.
I was looking for an open source WebRTC MCU that could help you do
this and found this: http://sourceforge.net/projects/mcumediaserver/ .
I have not tried it nor am I related to it in any way, but it might be
worthwhile to play with it.

HTH,
Silvia.