Audio Encodings
Audio Encodings
|
encoding |
encoding |
sample/frame |
bits/sample |
ms/frame |
|---|---|---|---|---|
|
DVI4 |
Interactive Multimedia Assoc.’s DVI ADPCM Wave Type |
sample |
4 |
|
|
G722 |
ITU’s G.722: 7 kHz audio-coding within 64 kbit/s |
sample |
8 |
|
|
G723 |
ITU’s G.723: Dual-rate speech coder for multimedia communications transmitting at 5.3 and 6.3 kbit/s |
frame |
N/A |
30.0 |
|
G726 |
ITU’s G.726 |
frame |
N/A |
|
|
G728 |
ITU’s G.728: 16 kbit/s using low-delay CELP |
frame |
N/A |
2.5 |
|
G729 |
ITU’s G.729: 8 kbit/s using conjugate structure-algebraic code excited linear prediction (CS-ACELP) |
frame |
N/A |
10.0 |
|
GSM |
GSM 06.10: RPE/LTP (residual pulse excitation/long term prediction) coding at a rate of 13 kb/s |
frame |
N/A |
20.0 |
|
L8 |
8 bit linear |
sample |
8 |
|
|
L16 |
16 bit linear |
sample |
16 |
|
|
LPC |
Linear Predictive Coding |
frame |
N/A |
20.0 |
|
MPA |
MPEG-I or MPEG-II audio encapsulated as elementary streams, from ISO standards ISO/IEC 11172-3 & 13818-3 |
frame |
N/A |
|
|
PCMA |
G.711 A-law |
sample |
8 |
|
|
PCMU |
G.711 mu-law |
sample |
8 |
|
|
QCELP |
frame |
variable |
20.0 |
|
|
VDVI |
variable-rate version of DVI4 |
sample |
variable |
See also internet Low Bitrate Codec (iLBC) http://www.ilbcfreeware.org/ Links to an external site. [RFC 3952] (now WebRTC project (webrtc.org). See also wideband CODECs, such as Extended Adaptive Multi-Rate Wideband (AMR-WB+) Audio Codec [RFC 4352, RFC 4348, RFC 4424]
Slide Notes
[RFC 3551] H. Schulzrinne and S. Casner, ‘RTP Profile for Audio and Video Conferences with Minimal Control’, Internet Request for Comments, vol. RFC 3551 (INTERNET STANDARD), Jul. 2003 [Online]. Available: http://www.rfc-editor.org/rfc/rfc3551.txt Links to an external site.
[RFC 3952] A. Duric and S. Andersen, ‘Real-time Transport Protocol (RTP) Payload Format for internet Low Bit Rate Codec (iLBC) Speech’, Internet Request for Comments, vol. RFC 3952 (Experimental), Dec. 2004 [Online]. Available: http://www.rfc-editor.org/rfc/rfc3952.txt Links to an external site.
[RFC 4424] S. Ahmadi, ‘Real-Time Transport Protocol (RTP) Payload Format for the Variable-Rate Multimode Wideband (VMR-WB) Extension Audio Codec’, Internet Request for Comments, vol. RFC 4424 (Proposed Standard), Feb. 2006 [Online]. Available: http://www.rfc-editor.org/rfc/rfc4424.txt Links to an external site.
[RFC 4348] S. Ahmadi, ‘Real-Time Transport Protocol (RTP) Payload Format for the Variable-Rate Multimode Wideband (VMR-WB) Audio Codec’, Internet Request for Comments, vol. RFC 4348 (Proposed Standard), Jan. 2006 [Online]. Available: http://www.rfc-editor.org/rfc/rfc4348.txt Links to an external site.
[RFC 4352] J. Sjoberg, M. Westerlund, A. Lakaniemi, and S. Wenger, ‘RTP Payload Format for the Extended Adaptive Multi-Rate Wideband (AMR-WB+) Audio Codec’, Internet Request for Comments, vol. RFC 4352 (Proposed Standard), Jan. 2006 [Online]. Available: http://www.rfc-editor.org/rfc/rfc4352.txt Links to an external site.
Transcript
[slide93] So I had all these different audio codings with different numbers of bits per sample, different frame lengths, etc. So this thing that I mentioned earlier, the low bitrate CODEC, was done by Professor Kleijn. It's used in the WebRTC product, but today one of the hot things is wideband CODECs. Really high-quality audio. That's right, so I'm getting audio, 16-bit sample, better than CD quality audio. Right?