Audio Codecs

Transcodable Audio Codecs

The following codecs can be used when setting codec_string and absolute_codec_string.

• OPUS
  • opus@48000h@10i - Opus 48khz using 10 ms ptime (mono and stereo)
  • opus@48000h@20i - Opus 48khz using 20 ms ptime (mono and stereo)
  • opus@48000h@40i - Opus 48khz using 40 ms ptime
  • opus@16000h@10i - Opus 16khz using 10 ms ptime (mono and stereo)
  • opus@16000h@20i - Opus 16khz using 20 ms ptime (mono and stereo)
  • opus@16000h@40i - Opus 16khz using 40 ms ptime
  • opus@8000h@10i - Opus 8khz using 10 ms ptime (mono and stereo)
  • opus@8000h@20i - Opus 8khz using 20 ms ptime (mono and stereo)
  • opus@8000h@40i - Opus 8khz using 40 ms ptime
  • opus@8000h@60i - Opus 8khz using 60 ms ptime
  • opus@8000h@80i - Opus 8khz using 80 ms ptime
  • opus@8000h@100i - Opus 8khz using 100 ms ptime
  • opus@8000h@120i - Opus 8khz using 120 ms ptime
    • provided by mod_opus
• iSAC
  • provided by mod_isac
• CODEC2 2550bps) 8000hz 20ms
  • provided by: mod_codec2
• SILK Skype Audio codec.
  • Provided by mod_silk.
• iLBC@30i - iLBC using mode=30 which will win in all cases.
  • Provided by mod_ilbc
• Speex
  • speex@8000h@20i - Speex 8kHz using 20ms ptime.
  • speex@16000h@20i - Speex 16kHz using 20ms ptime.
  • speex@32000h@20i - Speex 32kHz using 20ms ptime.
    • Provided by mod_speex
• BroadVoice.
  • BV32 - BroadVoice 16kHz, 32kb/s wideband
  • BV16 - BroadVoice 8kHz, 16kb/s narrowband
    • Provided by mod_bv.
• Siren
  • G7221@16000h - G722.1 16kHz (aka Siren 7)
  • G7221@32000h - G722.1C 32kHz (aka Siren 14)
    • Provided by mod_siren
• CELT wideband.
  • CELT@32000h - CELT 32kHz, only 10ms supported
  • CELT@48000h - CELT 48kHz, only 10ms supported
    • Provided by mod_celt
• DVI
  • DVI4@8000h@20i - IMA ADPCM 8kHz using 20ms ptime. (multiples of 10)
  • DVI4@16000h@40i - IMA ADPCM 16kHz using 40ms ptime. (multiples of 10)
• GSM@40i - GSM 8kHz using 40ms ptime. (GSM is done in multiples of 20, Default is 20ms)
• G722 - G722 16kHz using default 20ms ptime. (multiples of 10)
  • Provided by mod_spandsp
• G.726
  • G726-16 - G726 16kbit adpcm using default 20ms ptime. (multiples of 10)
  • G726-24 - G726 24kbit adpcm using default 20ms ptime. (multiples of 10)
  • G726-32 - G726 32kbit adpcm using default 20ms ptime. (multiples of 10)
  • G726-40 - G726 40kbit adpcm using default 20ms ptime. (multiples of 10)
  • AAL2-G726-16 - Same as G726-16 but using AAL2 packing. (multiples of 10)
  • AAL2-G726-24 - Same as G726-24 but using AAL2 packing. (multiples of 10)
  • AAL2-G726-32 - Same as G726-32 but using AAL2 packing. (multiples of 10)
  • AAL2-G726-40 - Same as G726-40 but using AAL2 packing. (multiples of 10)
• LPC - LPC10 using 90ms ptime (only supports 90ms at this time in FreeSWITCH)
  • Provided by mod_spandsp.
• G729 - G729 in transcoding mode
  • provided by: mod_com_g729
• PCMU - G711 8kHz ulaw using default 20ms ptime. (multiples of 10)
• PCMA - G711 8kHz alaw using default 20ms ptime. (multiples of 10)
• L16 - L16 isn't recommended for VoIP but you can do it. L16 can exceed the MTU Rather quickly.
  • Provided in core PCM module.

Pass-through Audio Codecs

• G729 - G729 in passthru mode. (mod_g729 / mod_com_g729)
  • Provided by mod_g729 for passthru mode and mod_com_g729 for commercial license (10USD per channel)
• G723 - G723.1 in passthru mode. (mod_g723_1)
  • Provided in mod_g723.1.
• AMR - AMR in passthru mode. (mod_amr)
  • Provided by mod_amr.
• AMR-WB (G.722.2) - AMR-WB in passthru mode. (mod_amr_wb)
  • Provided by mod_amr_wb.