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Based on the renowned Code Excited Linear Prediction (CELP) coding model, the G.729 speech compression standard delivers toll-quality speech, similar in quality to 32-kbps ADPCM but at one-quarter the bit rate.
With the low rate of 8 kbps, G.729 is the lowest bit rate ITU-T standard with toll quality, offering opportunities for significant increases in bandwidth utilization in existing telephony and wireless applications.
G.729 operates on 10-ms frames, allowing moderate transmission delays, so applications such as teleconferencing or visual telephony, where quality, delay and bandwidth are all important, will benefit substantially from this codec.
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Platforms – G.729
For implementations of G.729 and its annexes on other platforms, please contact sales@voiceage.com
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Developed through the collaboration of Université de Sherbrooke (a shareholder of VoiceAge), France Telecom, and Nippon Telegraph and Telephone Corporation (NTT), G.729 is widely used, for example in the NTT DoCoMo network.
VoiceAge also offers implementations of G.729 Annexes A, B, D and E.
Technology
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Encoded bandwidth |
~ 200-3400 Hz |
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Standardized |
ITU-T 1995 |
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Coding type |
CS-ACELP (Conjugate-Structure Algebraic Code Excited Linear Prediction) |
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Bit rate |
8 kbps |
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Delay (ms):
Frame size
Lookahead |
10
5
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Quality |
Toll |
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Complexity:
MIPS
RAM (words) |
20-25
< 4 K
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Applications
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Digital telephony – VoIP, Voice over ATM, Voice over Frame Relay, wireless, satellite, cable
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Videoconferencing, teleconferencing
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Multimedia, e.g., Digital Simultaneous Voice and Data
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Voicemail
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Media gateways
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Test and measurement equipment
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PDA/handset-hosted applications
G.729A
The G.729 Annex A: DSVD (Digital Simultaneous Voice and Data) – is a low-complexity version of the G.729 standard. G.729 Annex A offers the best complexity/quality ratio in the industry. |
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Platforms – G.729A
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Technology
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Encoded bandwidth |
~ 200-3400 Hz |
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Standardized |
ETSI 1999 |
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Coding type |
CS-ACELP (Conjugate-Structure Algebraic Code Excited Linear Prediction) |
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Bit rate |
8 kbps |
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Delay (ms):
Frame size
Lookahead |
10
5
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Quality |
Toll |
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Complexity:
MIPS
RAM (words) |
10
2 K
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G.729B
G.729 Annex B: VAD/CNG/DTX (Voice Activity Detection/Comfort Noise Generator/Discontinuous Transmission) defines the VAD/DTX/CNG features for G.729 and G.729A.
Only VoiceAge® offers a G.729B ACM driver customized to work directly with the Microsoft® RTC (Real-Time Communications) layer. RTC provides an interface to the RTP (Real-Time Transport Protocol) layer, which supports transmission of voice over IP (VoIP) and instant messaging. |
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Platforms – G.729B
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Technology
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Standardized |
ITU-T 1996 |
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Coding type |
CS-ACELP (Conjugate-Structure Algebraic Code Excited Linear Prediction) |
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Bit rate |
<= 8 kbps |
G.729D
G.729 Annex D operates at a bit rate of 6.4 kbps. |
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Platforms – G.729D
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Technology
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Standardized |
ITU-T 1998 |
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Coding type |
CS-ACELP (Conjugate-Structure Algebraic Code Excited Linear Prediction) |
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Bit rate |
6.4 kbps |
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Delay (ms):
Frame size
Lookahead
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10
5 |
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Quality |
< Toll |
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Complexity:
MIPS
RAM (words)
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20
< 4 K |
G.729E
G.729 Annex E operates at a bit rate of 11.8 kbps. |
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Platforms – G.729E
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Technology
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Standardized |
ITU-T 1998 |
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Coding type |
CS-ACELP (Conjugate-Structure Algebraic Code Excited Linear Prediction) |
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Bit rate |
11.8 kbps |
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Delay (ms):
Frame size
Lookahead |
10
5 |
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Quality |
Toll |
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Complexity:
MIPS
RAM (words) |
25-30
< 6 K |
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