TopView voice calls over VOIP allow the specification of a codec used for encoding the audio to be used during the call. This article explains what codecs are and why you might want to use a codec that is different from the defaults used by TopView.
From Wikipedia’s definition of Audio Codec:
An audio codec is a codec (a device or computer program capable of encoding or decoding a digital data stream) that encodes or decodes audio
Name | Alt. name | Payload type | No. of channels | Rate (Hz) | Ratet (Hz) |
PCMU (G.711) | PCMU | 0 | 1 | ITU-T G.711 PCM µ-Law audio 64 kbit/s | 8000 |
PCMA (G.711) | PCMA | 8 | 1 | ITU-T G.711 PCM A-Law audio 64 kbit/s | 8000 |
G.722 | G722 | 9 | 1 | ITU-T G.722 audio 64 kbit/s. Usually the codec in use for TopView voice calls. It is of excellent quality. | 8000 |
G.723 | G723 | 4 | 1 | Obsoleted codec superseded by G726 | 8000 |
G.726-16 | G726 | 104 | 1 | ITU-T G.726 audio 16 kbit/s | 8000 |
G.726-24 | G726 | 105 | 1 | ITU-T G.726 audio 24 kbit/s | 8000 |
G.726-32 | G726 | 106 | 1 | ITU-T G.726 audio 32 kbit/s | 8000 |
G.726-40 | G726 | 107 | 1 | ITU-T G.726 audio 40 kbit/s | 8000 |
G.728 | G728 | 15 | 1 | ITU-T G.728 audio 16 kbit/s | 8000 |
G.729 | G729 | 18 | 1 | ITU-T G.729 and G.729a audio 8 kbit/s; Annex B is implied unless the annexb=no parameter is used | 8000 |
GSM | GSM | 3 | 1 | European GSM Full Rate audio 13 kbit/s (GSM 06.10) | 8000 |
iLBC | iLBC | 98 | 1 | Internet low Bitrate Codec 13.33 or 15.2 kbit/s | 8000 |
L16 (2 channel) | L16 | 10 | 2 | Linear PCM 16-bit stereo audio | 44100 |
L16 | L16 | 11 | 1 | Linear PCM 16-bit audio | 44100 |
opus | opus | 120 | 1 | Opus audio | 48000 |
SPEEX-Narrow | SPEEX | 97 | 1 | Speex audio | 8000 |
SPEEX-Wideband | SPEEX | 100 | 1 | Speex audio | 16000 |
SPEEX-Dynamic | SPEEX | 108 | 1 | Speex audio | 32000 |