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The word codec is a portmanteau of 'compressor-decompressor' or, more commonly, 'coder-decoder'....A codec encodes a data stream or signal for transmission, storage or encryption, or decodes it for playback or editing. Codecs are used in videoconferencing, streaming media and video editing applications.
As with conventional telephony, with VoIP the speech is initially captured in analog form with a microphone. This analog information is then transferred into a digital format by a converter and changed through codecs into corresponding audio-binary formats. Depending on the codec used, the data can be compressed to differing extents in this process.
Most codecs use a procedure through which - similar to MP3 files - information not important for the human ear is omitted. This reduces the amount of data and thus reduces the bandwidth required for transfer. However, if too much information is omitted, the speech quality will suffer.
The different codec procedures master the audio compression with different levels of efficiency. Some are specifically designed to achieve a low bandwidth at any cost. Depending on the codec, therefore, the necessary bandwidth and the speech quality will vary. In order for the data also to be converted correctly back into speech after the transport, the receiver must use the same codec as the sender.
Codec Name Coding Type Frequency (Hz) Bandwith (kbps) Value snom3xx/820/710 snom720/760 snom821/870 snomMP G.722 SB-ADPCM 50-7000 (wideband) 64 g722 G.711ulaw PCM 200-3500 (narrowband) 64 pcmu G.711alaw PCM 200-3500 (narrowband) 64 pcma GSM-FR RPE-LTP 200-3500 (narrowband) 13 gsm G.723.1 MPC-MLQ 200-3500 (narrowband) 6.3 g723 G.723.1 ACELP 200-3500 (narrowband) 5.3 g723 G.726-16 ADPCM 200-3500 (narrowband) 16 g726-16 G.726-24 ADPCM 200-3500 (narrowband) 24 g726-24 G.726-32 ADPCM 200-3500 (narrowband) 32 g726-32 G.726-40 ADPCM 200-3500 (narrowband) 40 g726-40 AAL2-G.726-16 ADPCM 200-3500 (narrowband) 16 aal2-g726-16 AAL2-G.726-24 ADPCM 200-3500 (narrowband) 24 aal2-g726-24 AAL2-G.726-32 ADPCM 200-3500 (narrowband) 32 aal2-g726-32 AAL2-G.726-40 ADPCM 200-3500 (narrowband) 40 aal2-g726-40 AMR-WB (G.722.2) ACELP 50-7000 (wideband) 6.6 amrwb-0 AMR-WB (G.722.2) ACELP 50-7000 (wideband) 8.75 amrwb-1 AMR-WB (G.722.2) ACELP 50-7000 (wideband) 12.65 amrwb-2 AMR-WB (G.722.2) ACELP 50-7000 (wideband) 14.25 amrwb-3 AMR-WB (G.722.2) ACELP 50-7000 (wideband) 15.85 amrwb-4 AMR-WB (G.722.2) ACELP 50-7000 (wideband) 18.25 amrwb-5 AMR-WB (G.722.2) ACELP 50-7000 (wideband) 19.85 amrwb-6 AMR-WB (G.722.2) ACELP 50-7000 (wideband) 23.05 amrwb-7 AMR-WB (G.722.2) ACELP 50-7000 (wideband) 23.85 amrwb-8 G.729A CS-ACELP 200-3500 (narrowband) 8 g729-annexb=no G.729AB CS-ACELP 200-3500 (narrowband) 8 g729 cn telephone-event
- AMR-WB is not included in the standard FW. Please contact your snom Sales representative for further information.
- cn is only supported from FW version 8.7.3 onwards
- 720/760 do not support the following paket sizes with the following codecs - G722: 40, 60 ms; G711: 60 ms; g726 (all variants): 40, 60 ms; AAL2*: 60 ms;
This category has the following 3 subcategories, out of 3 total.