Narrowband Speech Codecs by VoiceAge Corporation

Audio and Voice Solutions

Product Description

- Adaptive Multi-Rate (AMR Narrowband)
- G.729A/B
- ACELP®.net

The AMR (Adaptive Multi-Rate) narrowband standard speech codec operates at variable bit rates of 4.75-12.2 kbps and provides toll-quality speech at 7.4 kbps, with near-toll quality at lower rates and greater robustness at higher rates. It was adopted by ETSI and 3GPP as the mandatory codec for 2.5G & 3G wireless systems based on the evolved GSM core network (W-CDMA, EDGE, GPRS).

Built-in voice activity detection/discontinuous transmission/comfort noise generation (VAD/DTX/CNG) dramatically frees up network resources and prolongs terminal battery life. Coded AMR media can be encapsulated in 3GPP or MPEG-4 file formats and used along the entire delivery chain in multimedia applications.

G.729 is the dominant speech codec for VoIP applications, adopted by the ITU-T and recommended by ARIB for 2G wireless handsets in Japan. Similar in quality to 32-kbps ADPCM, G.729 delivers toll-quality speech at a low 8 kbps, providing opportunities for significant increases in bandwidth utilization. G.729A is a low-complexity version of G.729; G.729B defines VAD/DTX/CNG features for G.729 and G.729A.

ACELP®.net meets the needs of IP networks and the PC platform through an improved packetization method that outperforms conventional approaches. In particular, it minimizes the impact of errors while significantly improving error correction possibilities in case of data-packet losses. Through frame concatenation and interlacing, the communication channel is made more robust.

The ACELP®.net family includes a dual-rate codec (8.5/6.5 kbps), a fixed rate codec (5.0 kbps) and a wideband codec (16 kbps). The dual-rate version of ACELP®.net can switch bit rates on the fly to better handle network congestion or degradation. ACELP®.net provides toll-quality speech at 8.5 kbps, near-toll quality at lower rates and better-than-toll with wideband coding.

ACELP®.net is the preferred low bit rate speech codec in RealAudio® and is included in both Microsoft MediaPlayer® and Audible® ready equipment.

The VoiceAge implementations of these key, high-quality, standard codecs are optimized for low-resource devices (low memory and computational resources) powered by ARM processors. Our off-the-shelf implementations are ideally suited for integration into a variety of handheld devices. Written in C or C++, a compiled implementation is available for any ARM-powered platform. Support for a variety of operating systems including Symbian, WinCE/Mobile, Linux and Palm guarantees the applicability of these turnkey solutions to a broad range of manufacturers’ devices.

VoiceAge has optimized the standards specifically for the ARM platform. We've solved the development problems so you don't have to. Our implementations have been validated against the reference test sequence for bit-exactness and work right out of the box.

Narrowband Speech Codecs

Market Segment(s)

• Embedded
• Enterprise
• Home
• Mobile

Target Platform(s)

• Java
• Linux
• Palm OS
• Symbian
• VxWorks
• Windows Embedded CE
• Windows Mobile

ARM Processor(s)

• ARM7EJ-S
• ARM7TDMI
• ARM7TDMI-S
• ARM720T
• ARM920T
• ARM922T
• ARM926EJ-S
• ARM940T
• ARM946E-S
• ARM966E-S
• ARM968E-S
• ARM1020E
• ARM1022E
• ARM1026EJ-S
• ARM1136J-S
• ARM1136JF-S
• ARM1156T2(F)-S
• ARM1176JZ(F)-S
• Cortex-A53
• Cortex-A57
• ARMv8
• StrongARM
• XScale

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