Administrator’s Guide for VP530 IP
Video
Phone
142
This chapter provides information for making configuration changes for the following
audio features:
CODEC is an abbreviation of COmpress-DECompress. It is capable of coding or
decoding a digital data stream or signal by implementing an algorithm. The object of
the algorithm is to represent the high-fidelity audio signal with minimum number of bits
while retaining the quality. This can effectively reduce the frame size and the bandwidth
required for transmission of the audio.
The default codecs used on the IP phone are summarized in the following table:
Codec
Algorithm
Bit Rate
Sample Rate
Packetization Time
PCMA
G.711 a-law
64 Kbps
8 Ksps
20ms
PCMU
G.711 u-law
64 Kbps
8 Ksps
20ms
G729
G.729
8 Kbps
8 Ksps
20ms
G722
G.722
64 Kbps
16 Ksps
20ms
In addition to the codecs introduced above, the IP phone also supports the codecs:
G723, AACLC, iLBC, H264, H263 and mp4v-es. You can configure the preferred codecs to
use on a per-account basis instead of using the default codecs. You can also configure
the priorities for the enabled codecs. The attribute “rtpmap” is used to define a
mapping from RTP payload codes to a codec, clock rate and other encoding
parameters.
The corresponding attributes of the audio codec are listed as follows:
Codec
Configuration Method
Priority
RTPmap
PCMU
Configuration Files
Web User Interface
1
0
PCMA
Configuration Files
Web User Interface
2
8
G729
Configuration Files
Web User Interface
3
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Summary of Contents for VP530 IP
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Page 12: ......
Page 111: ...Configuring Basic Features 99...
Page 153: ...Configuring Advanced Features 141...
Page 171: ...Configuring Security Features 159...
Page 182: ...Administrator s Guide for VP530 IP Video Phone 170 Phonebook on page 266...
Page 183: ...Resource Files 171...
Page 194: ...Administrator s Guide for VP530 IP Video Phone 182 3 Click OK to confirm the resetting...
Page 195: ...Troubleshooting 183...
Page 344: ...Administrator s Guide for VP530 IP Video Phone 332...