Transcoding video decoding queue size issue


New Member

I am facing issue of transcoding_video_decoding_average_queue_size when it gets to 100. Feed is getting freeze and delay after that. Facing this issue after concurrent veiwers going above around 1700.

I am playing stream with low resolution and low bitrate(200kbps)

My server configuration is as below:
AMD Epyc 7351P - 16c/ 32 t - 2.4GHz / 2.9GHz
128 GB DDR4 ECC 2400MHz
2 x 500 GB SSD NVMe Soft RAID
3Gbps Network Guaranteed
Unlimited Bandwidth

This is what i have observed, may be the issue is different. Let me now if you need more details.

Last edited:


Staff member
Good day.
Please make sure you've done the perfomance tuning described here (espesially p 11, 12, 13), and stream distribution optimization is enabled.
Also, you coonfuguration seems not enough for 1700 subscribers. In our tests in the article What kind of server do you need to run a thousand WebRTC streams? we handle 1000 subscribers without transcoding on server with the following capabilities:
  • 2x Intel(R) Xeon(R) Silver 4214 CPU @ 2.20GHz ( 24 cores, 48 threads in total);
  • 192GB RAM;
  • 2x 10Gbps
About transcoding. Please check if you really need it because it dramatically increases CPU load: 1 CPU core is required for 3 480p streams or 2 720p streams encoding.
So you should check the following:
- if you explicitly set playback resolution in constraints
- if you publish one codec (for example, H264) and play another one (for example, VP8)
- if you publish WebRTC and play it using WSPlayer (this is obsolete, consider to use WebRTC to play)
- if you publish VP8 WebRTC and re-publish it as RTMP to third party server
See also the full list of the cases in which transcoding is enabled.
If you really need to transcode streams and to play it with a huge amount of subscribers, please consider CDN with a separate Transcoder server.