Difference between revisions of "Codecs"
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= Transcoding = | = Transcoding = | ||
Transcoding is conversion from one codec to another. It is performed by Asterisk when LegA and LegB (user's and provider's) codecs do not match. Transcoding uses lot of system resources, so it should be avoided to get better server performance. | Transcoding is conversion from one codec to another. It is performed by Asterisk when LegA and LegB (user's and provider's) codecs do not match. Transcoding uses a lot of system resources, so it should be avoided to get better server performance. | ||
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= For more information please visit = | = For more information please visit = | ||
Revision as of 16:34, 17 January 2012
Description
Codecs are used to convert an analog voice signal to digitally encoded version. Codecs vary in the sound quality, the bandwidth required, the computational requirements, etc
List of codecs supported by MOR can be found here.
Per Call Bandwidth requirements for various codecs
| Codec & Bit Rate (Kbps) | Codec Sample Size (Bytes) | Codec Sample Interval (ms) | Voice Payload Size (Bytes) | Voice Payload Size (ms) | Bandwidth Ethernet (Kbps) |
| G.711 (64 Kbps) | 80 Bytes | 10ms | 160 bytes | 20ms | 87.2Kbps |
| G.729 (8 Kbps) | 10 Bytes | 10ms | 20 bytes | 20ms | 31.2Kbps |
| G.723.1 (6.3 Kbps) | 24 Bytes | 30ms | 24 bytes | 30ms | 21.9Kbps |
| G.723.1 (5.3 Kbps) | 20 Bytes | 30ms | 20 bytes | 30ms | 20.8Kbps |
| G.726 (32 Kbps) | 20 Bytes | 5ms | 80 bytes | 20ms | 55.2Kbps |
| G.726 (24 Kbps) | 15 Bytes | 5ms | 60 bytes | 20ms | 47.2Kbps |
| G.728 (16 Kbps) | 10 Bytes | 5ms | 60 bytes | 30ms | 31.5Kbps |
| G722_64k(64 Kbps) | 80 Bytes | 10ms | 160 bytes | 20ms | 87.2Kbps |
| ilbc_mode_20(15.2Kbps) | 38 Bytes | 20ms | 38 bytes | 20ms | 38.4Kbps |
| ilbc_mode_30(13.33Kbps) | 50 Bytes | 30ms | 50 bytes | 30ms | 28.8Kbps |
| speex(24.6 Kbps) | 66 Bytes | 20ms | 56 bytes | 25ms | 42.4 Kbps |
| speex(18.2 Kbps) | 46 Bytes | 20ms | 56 bytes | 20ms | 42.4 Kbps |
Transcoding
Transcoding is conversion from one codec to another. It is performed by Asterisk when LegA and LegB (user's and provider's) codecs do not match. Transcoding uses a lot of system resources, so it should be avoided to get better server performance.
For more information please visit
- A more detailed guide about bandwidth calculations ant related metrics
- Also here
- A simple bandwidth calculator can be found here
- Speex codec install
