22
CONFIDENTIAL
DOC-USR-0024-06
____________________________________________________________________________________
Z3 Technology, LLC
♦
100 N. 8th St. STE 250
♦
Lincoln, NE 68508-1369 USA
♦
+1.402.323.0702
7.11
Adjusting for Latency and Quality
For latency, the key parameters to work with are Video Burst Size and B-frame Interval.
Video Burst Size 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 (B-frame Interval should be set to “1”).
shows the suggested values for Video Burst Size and B-frame Interval for 3 common use cases:
Video Burst Size
B-frame
Interval
Case 1: Highest Quality, Highest Latency
2000
3
Case 2: Good Quality, Standard Latency
1000
2
Case 3: Normal Quality, Lowest Latency
150
1
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)
Figure 17 Tuning for Various Use Cases
