Codec Quality Comparison
These are the results of MUSHRA tests with 10 listeners. The first graph is for the 48 kbit/s listening test.
The second graph is for the 64 kbit/s listening test. Note that G.722.1C is still at 48 kbit/s in that test because it is the highest bit-rate it supports.
Codec Feature Comparison
| Codec | Rate (kHz) | bitrate (kbps) | frame size (ms) | total delay (ms) | Robustness | license |
|---|---|---|---|---|---|---|
| CELT | 44.1, 48 |
24-128 (mono) 40-160 (stereo) |
<5.8 (44.1 kHz) <5.3 (48 kHz) |
<8.7 (44.1 kHz) <8.0 (48 kHz) |
packet loss, bit errors | open-source/ free software |
| G.722.1C | 32 | 24, 32, 48 | 20 | 40 | packet loss, bit errors | no charge, but not open-source |
| AAC-LD | 16-48 | 16-128 | from 10 to 11.6 | from 20 to 50+ | packet loss | proprietary, MPEG |
| Fraunhofer ULD | 32-48 | 48-192? | <10 | <10 | limited | proprietary, non-standard |
Definitions
- multi-rate
- Allows the codec to change bitrate dynamically, at any moment
- bit-robust
- Robust to corruption at the bit level (as found on wireless networks) and to loss of entire packets (as on packet networks)