H3C Technologies H3C MSR 50 - Manual (Page 619)

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Advanced settings
This section provides information on configuring various advanced settings.
Introduction to advanced settings
Coding parameters
The configuration of coding parameters includes specifying codec priorities and packet assembly
intervals.
The codecs include: g711alaw, g711ulaw, g723r53, g723r63, g726r16, g726r24, g726r32, g726r40,
g729a, g729br8, and g729r8.
The following are the characteristics of different codecs.
• g711alaw and g711ulaw provide high-quality voice transmission, while requiring greater
bandwidth.
• g723r53 and g723r63 provide silence suppression technology and comfortable noise. The
relatively higher speed output is based on multi-pulse multi-quantitative level technology and
provides relatively higher voice quality. The relatively lower speed output is based on the
Algebraic-Code-Excited Linear-Prediction technology and provides greater flexibility for
application.
• The voice quality provided by g729r8 and g729a is similar to the adaptive differential pulse code
modulation (ADPCM) of 32 kbps, having the quality of a toll. Also, it features how bandwidth,
lesser event delay, and medium processing complexity. Therefore, it has a wide field of application.
Table 218 Relationship between algorithms and bandwidth
Codec Bandwidth Voice quality
G.711 (A-law and μ-law) 64 kbps (without compression) Best
G.726 16, 24, 32, 40 kbps Good
G.729 8 kbps Good
G.723 r63 6.3 kbps Fair
G.723 r53 5.3 kbps Fair
Actual network bandwidth is related to packet assembly interval and network structure. The longer the
packet assembly interval, the closer the network bandwidth is to the media stream bandwidth. More
headers consume more bandwidth. A longer packet assembly interval results in a longer fixed coding
latency.
The following tables show the relevant packet assembly parameters without IPHC, including packet
assembly interval, bytes coded in a time unit, and network bandwidth. Therefore, you can choose a
suitable codec algorithm according to idle and busy status of the line and network situations more
conveniently.