CONFIDENTIAL
DOC-USR-0027-07
___________________________________________________________________________________________
Z3 Technology, LLC
♦
100 N 8
th
ST, STE 250
♦
Lincoln, NE 68508-1369 U.S.A.
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+1.402.323.0702
19
5.8
Tuning for Latency
For latency, the key parameters to work with are Video Delay and Number of B-frames.
Video Delay defines the number of milliseconds of buffering the encoder has to work with. The higher
this value, the more buffers it has to work with and the more time it has to “smooth things out” for
challenging content. However, a higher value also causes latency to increase accordingly. To minimize
latency, this value should be set to the lowest possible value. The lowest value Z3 recommends is 100.
B-frames improve the quality of the picture, but they also increase the latency by 1 frame time. To
minimize latency, the number of B-frames should be set to 0.
shows the suggested values for Video Delay and Number of B-frames for 3 common use cases:
Video Delay
# of B-frames
Case 1: Highest Quality, Highest Latency
9999
3
Case 2: Good Quality, Standard Latency
2000
1
Case 3: Normal Quality, Lowest Latency
100
0
Figure 17 Tuning for Various Use Cases
RTP offers lower latency than UDP, so for the lowest latency you should use RTP.
If you are streaming to VLC, you can reduce latency on the decode side by adjusting the network caching
value. By default, this is set to 1000ms. You can lower this to as low as 200ms. To do this, go to the
following:
VLC
→
Tools
→
Preferences
→
Show Settings (ALL)
→
Input / Codecs
→
Network caching (ms)
