//转载 - sip codec
编码速率(Codec Bit Rate)=编码采样大小(Codec Sample Size)/采样频率(Codec Sample Interval)
G.711:64kbps=80Bytes/10ms=640bit/10ms=640bit/0.01s=64000bit/s=64kbps
G.729:8kbps=10Bytes/10ms=80bit/10ms=80bit/0.01s=8000bit/s=8kbps
G.723.1:6.3kbps=24Bytes/30ms=8Bytes/10ms=8*8bit/0.01s=6400bit/s=6.4kbps
Mos：语音质量评级，范围从1(差)-5（好）
Voice Payload Size(Bytes):语音载荷bytes/bits数量，支持多种采样大小
Voice Payload Size(ms):在编码采用中可以体现
G.711:160Bytes/20ms=8Bytes/ms=64kbps
G.729:20Bytes/20ms=1Bytes/ms=8kbps
G.729:60Bytes/30ms=2Bytes/ms=16kbps
PPS:每秒传递packets的数量，等于编码速率/载荷大小
G.711:50pps=64kbps/1280bits pre packet=64kbps/160Bytes
G.729:50pps=8kbps/160bits pre packet=8kbps/20Bytes
带宽计算
包大小=L2(FRF.12/Ethernet)+IP/UDP/RTP包头+语音载荷
每秒包的数量(PPS)=编码速率/载荷大小
带宽=包大小*PPS
固定包头大小(66bytes)=L2(26)+IP(20)+UDP(8)+RTP(12)
G.711
包大小=(26/L2+20/IP+8/UDP+12/RTP+160/G711)*8=1808bit
带宽=1808*50=90.4kbps
G.729
包大小=(66+20)*8=688
带宽=688*50=34.4kbps