Stream desktop over RTP using VLC with the lowest latency possible

Question

I have been trying to figure out how to stream my desktop (over LAN) using VLC and to achieve the lowest latency possible (<100ms). The goal is to have another computer receive the stream and potentially play games while streaming (i.e playing game from PC1 on the PC beside the TV).

What settings should I use? I have tried multiple approaches but have yet to succeed.

EDIT: I am open to using something other than VLC as well.

Leitmotiv

Answer 1

I have also tried the same with VLC and couldn't ever get latency bellow 3 seconds. FFmpeg did wonders and finally provided a latency bellow 1 second.

mpeg2video and UPD provided the best results, RTP latency felt a bit worse but very close. Moving to x264 improves quality in exchange for a bit more latency, but that really depends on how much dynamic content is there and how fast the CPU is. I only got x264 working with UDP, but there must be a way to do it with RTP.

I'm not sure it's feasible for playing. The server will be under a heavy workload and latency will be noticeable - at least on Linux, don't know about windows.

On Linux try one of the following commands:

$ ffmpeg -f x11grab -s 1600x900 -r 50 -vcodec mpeg2video -b:v 8000 -f rtp rtp://192.168.0.10:1234

or

$ ffmpeg -f x11grab -s 1600x900 -r 50 -vcodec libx264 -preset ultrafast -tune zerolatency -crf 18 -f mpegts udp://192.168.0.10:1234

Adjust for screen resolution (-s <your resolution>), refresh rate (-r <fps>), bandwidth (-b:v <bits/s>), quality (-crf 18 or -qp 18, the lower the better), and target ip:port.

If running Windows use dshow in place of x11grab.

Watch it using ffplay udp://192.168.0.10:1234 or ffplay sdp://192.168.0.10:1234.

Mind you that none of those options will stream sound. I was unable to get such low latencies when streaming audio as well. It might be doable, I just didn't figured out how.

The most responsive client was ffplay, VLC introduced too much latency even with its network cache set to zero - with such cache it actually got worse, since it tried to 'resync' the stream too often.

If you need further details I made a post about my findings. Hope it helps. I appreciate any feedback. ^_^

Susian

FFmpeg also has some x264 encoding settings like "-tune zerolatency" that might be useful here: trac.ffmpeg.org/wiki/StreamingGuide#Latency – Trying

I came to your website before running over this article. For my opinion vlc and ffplay had the almost same latency. – Apo

I'd tried to pass resolution parameter as below URL but it does't seems to work, i mean rtsp recorded mp4 video remains high resolution even if i've passed 320x240 :( "-t 30 -i \"rtsp://xxx.xxxxxx.com/2\" -s 320x240 -acodec copy -vcodec copy -to" – Summit

I get Output file #0 does not contain any stream – Alphonsealphonsine

Answer 2

It needs to set display like display 0 with -i :0.0 flag, following works for me, now i am trying to lower the latency without giving up the quality;

ffmpeg -f x11grab -i :0.0 -s 1920x1080 -r 1000 -vcodec libx264 -preset ultrafast -tune zerolatency -crf 18 -f mpegts udp://192.168.13.37:5000

Cattish