19
CONFIDENTIAL
DOC-USR-0054-02
____________________________________________________________________________________
Z3 Technology, LLC
♦
100 N. 8th St. STE 250
♦
Lincoln, NE 68508-1369 USA
♦
+1.402.323.0702
(30)
Open VLC to view your UDP stream (see ) and view the “Statistics” tab (see ). You will see a lower
value for the overall input rate and for the “content” rate:
The value of TS Rate must be higher than (video bit rate + audio bit rate) * 1.25. If an attempt is
made to input a value less than this, the error message “TS rate too small to carry elementary
streams” will appear.
5.8
Tuning for Latency
For latency, the key parameters to work with are Maximum Delay and Number of B-frames.
Maximum 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, B-frames should be disabled (done by setting “Number of B-frames” to 1).
Figure 19 shows the suggested values for Maximum Delay and Number of B-frames for 3 common use
cases:
Maximum Delay
# of B-frames
Case 1: Highest Quality, Highest Latency
9999
3
Case 2: Good Quality, Standard Latency
2000
2
Case 3: Normal Quality, Lowest Latency
100
1
Input bit rate lowered to 1Mbps
Content bitrate lowered to ~ 512K + 128K
Figure 18 Lower Bitrate and TS Rate Reflected in VLC
Figure 19 Tuning for Various Use Cases
(1)
