Codec Quality Comparison
Warning: these are machine-generated results (not from real listeners) and hence should be taken with a grain of salt.
Codec Feature Comparison
| Codec | Rate (kHz) | bitrate (kbps) | delay frame+lookahead (ms) | multi-rate | embedded | VBR | PLC | bit-robust | license |
|---|
| Speex | 8, 16, 32 | 2.15-24.6 (NB)
4-44.2 (WB) | 20+10 (NB)
20+14 (WB) | yes | yes | yes | yes |
| open-source/
free software |
| iLBC | 8 | 15.2 or 13.3 | 20+5 or 30+10 |
|
|
| yes |
| no charge, but not open-source |
| AMR-NB | 8 | 4.75-12.2 | 20+5? | yes |
|
| yes | yes | proprietary |
AMR-WB
(G.722.2) | 16 | 6.6-23.85 | 20+5? | yes |
|
| yes | yes | proprietary |
| G.722.1 (Siren7) | 16 | (16) 24, 32 | 20+20 | yes |
|
| yes | yes | no charge, but not open-source |
| G.729 | 8 | 8 | 10+5 |
|
|
| yes | yes | proprietary |
| GSM-FR | 8 | 13 | 20+? |
|
|
| ? | ? | patented? |
| GSM-EFR | 8 | 12.2 | 20+? |
|
|
| yes | yes | proprietary |
| G.723.1 | 8 | 5.3 6.3 | 37.5 |
|
|
| yes | ? | proprietary |
| G.728 | 8 | 16 | 0.625 |
|
|
|
|
| proprietary |
| G.722 | 16 | 48 56 64 | ? |
| yes |
|
| ? | ? |
Definitions
- multi-rate
- Allows the codec to change bitrate dynamically, at any moment
- embedded
- A codec that embeds narrowband bitstreams in wideband bitstreams
- VBR
- Variable bitrate
- PLC
- Packet loss concealment
- bit-robust
- Robust to corruption at the bit level, as found on wireless networks
Special Features
- Speex
- Speex supports intensity stereo encoding and 32 kHz sampling
- iLBC
- iLBC frames are encoded completely independently; while this provides better quality when 10% (or more) of the packets are being dropped, this makes the codec suboptimal for clean line conditions.