Description: NetTalk is a visual telephone software for local area networks and the Internet
A. The development environment
Windows2000 Server & Visual c ++6.0 & SDK
+ self-developed CWndX class library (equivalent to a simplified MFC window section)
2. Supporting environment
Windows98 / ME / 2000 / XP
3. The agreements and standards involved
Network transmission adopts UDP protocol, audio compression adopts g. 729 standard, video compression adopts h.263 standard
Four. The performance parameters
Based on audio frame, there are 240 sampling points per frame audio data, time is 240 * 1000/8000 = 30ms, and 8000 is the sampling rate of audio.
Data receiver queue buffer delay: 30 * 3 = 90ms
Data sending end recording delay: 30ms
Data compression and decompression time: < 40 ms
Network delay: < 100ms (I think the school net should be good)
Total delay: < 260 ms
According to VOIP standard, total delay < 300ms is acceptable, and the above calculation is conservative, and the actual situation may be much better.
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