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.