AMR

Designed to allow transcoder-free connectivity between GSM, US-TDMA and PDC networks, AMR is the 3GPP mandatory standard codec for narrowband speech and multimedia messaging services over GSM and evolved GSM (WCDMA, GPRS and EDGE) networks.

AMR operates at eight bit rates in the range of 4.75 to 12.2 kbps and was specifically designed to improve link robustness. AMR supports dynamic adaptation to network conditions, using lower bit rates during network congestion or degradation while preserving audio quality. By trading off the speech bit rate to channel coding, AMR maximizes the likelihood of receiving the signal at the far end. Adding this channel protection has proved more successful than allowing frame losses.

Platforms

For implementations of this codec on
other platforms, please contact sales@voiceage.com

AMR provides toll quality speech starting at 7.4 kbps, with near-toll quality at lower rates and greater robustness and better reproduction of non-speech sounds at higher rates. Because it consists of 8 rates, AMR can be considered to be the most widely deployed codec in the world today, operating in 2 billion wireless handsets as well as in base stations and other network equipment.

Technology

	Encoded bandwidth	~ 200-3400 Hz
	Standardized	ETSI 1999
	Coding type	ACELP® (Algebraic Code Excited Linear Prediction)
	Bit rate	4.75/5.15/5.9/6.7/7.4/7.95/10.2/12.2 kbps
	Delay (ms): Frame size Lookahead	20 5
	Quality	Toll
	Complexity: MIPS RAM (words)	15-20 4 K

Applications

Digital telephony – GSM and 2.5G/3G circuit switched telephony, VoIP, Wi-Fi, satellite telephony, Push to talk over Cellular, video telephony
Multimedia – Audio and videoconferencing (H.324 video), chat and virtual reality immersion environments, streaming, content downloads, Multimedia Messaging Services, digital radio broadcasting, audio books, real-time collaboration tools, PDA/handset-hosted applications, ringtones, content creation tools, multimedia transcoders, multimedia gateways, interactive gaming
Voicemail/Unified Messaging
Network analysis and simulation tools
Test and measurement equipment
Static answering machines
Media players
Media servers
Media gateways
Content creation tools
Consumer electronics
Toys