VOCAL offers the GSM 06.20 Half Rate (HR) vocoder as a standalone algorithm, as part of a modular software library suite, as well as with a VoIP stack for different integration options with user applications. The GSM 06.20 speech compression algorithm is optimized to run on all major DSPs and processors as a real-time implementation that can be configured to support multichannel applications. Our GSM 06.20 codec software may be licensed by developers as binary or source code with custom designs available to meet unique requirements. Contact us to discuss your application requirements.
GSM 06.20 Codec
GSM 06.20 half rate voice codec uses the VSELP (Vector-Sum Excited Linear Prediction) algorithm. The VSELP algorithm is an analysis-by-synthesis coding technique and belongs to the class of speech coding algorithms known as CELP (Code Excited Linear Prediction).
GSM 06.20 describes the detailed mapping between input blocks of 160 speech samples in 13 bit uniform PCM form into encoded blocks of 112 bits and from encoded blocks of 112 bits to output blocks of 160 reconstructed speech samples. The sampling rate is 8 000 sample/s leading to an average bit rate for the encoded bit stream of 5,6 kbit/s. The coding scheme is called Vector Sum Excited Linear Prediction (VSELP) coding.
- Full and half duplex modes of operation
- Passes ETSI test vectors
- Compliant with GSM 06.20 Recommendation
- Optimized for high performance on leading edge DSP architectures
- Multichannel implementation
- Multi-tasking environment compatible
- DAA interface using linear codec at 8.0 kHz sample rate
- Direct interface to 8.0 kHz PCM data stream (A-law or μ-law)
- North American/International Telephony (including caller ID) support available
- Simultaneous DTMF detector operation available – (less than 10 talkoff hits on Bellcore test tape set)
- MF tone detectors, general purpose programmable tone detectors/generators available
- Data/Facsimile/Voice Distinction available
- Common compressed speech frame stream interface to support systems with multiple speech coders
- Dynamic speech coders selection if multiple speech codecs available
- Can be integrated with G.168 Echo Canceller and Tone Detection/Regeneration modules
- Available with VoIP stack
VOCAL’s GSM 06.20 HR speech coder software is available for the following Platforms:
- Texas Instruments - C6000 (TMS320C62x, TMS320C64x, TMS320C645x, TMS320C67x, DaVinci), OMAP, C5000 (TMS320C54x, TMS320C55x)
- Analog Devices – Blackfin, ADSP-21xx, TigerSHARC, SHARC
- AMCC – PowerPC
- MIPS – MIPS32, MIPS64, MIPS4Kc
- ARM – ARM7, ARM9, ARM9E, ARM10E, ARM11, StrongARM, ARM Cortex-A8, Cortex-M1
- iPhone / iPad
- AMD x86
Please contact us for specific GSM 06.20 vocoder supported platforms.
VOCAL’s GSM 06.20 HR speech coder software is available for the following Operating Systems:
- Unix, Linux, uClinux
- Microsoft Windows ACM / RTC / CE / Mobile
- Mac OS
- Green Hills Software
Please contact us for other supported Operating Systems.