G.726 Vocoder Used for Speech Transmission

Toronto, Canada – GAO Research Inc. (www.GAOResearch.com) is offering its G.726 vocoder which is a superset of the ITU-T G.721 and G.723 standards and is originally designed as a half-rate alternative to G.711 audio companding. It is used in numerous applications such as speech transmission over digital networks, video conferencing, multimedia, and ISDN communications.

GAO Research’s G.726 vocoder complies with the ITU-T standard and operates at 40, 32, 24, and 16 kbps. It converts a 64 Kbps A – law or μ-law PCM channel to or from a 40, 32, 24 or 16 kbps channel. The conversion is applied to the PCM bit stream using an ADPCM transcoding technique. Thus, the scheme has switchable transmission rates providing 4 kHz of audio bandwidth in conformance with the ITU-T standard.

This G.726 vocoder can encode 13 or 14-bit PCM samples or 8-bit, A-law or μlaw encoded data into 2, 3, 4, or 5-bit code words. Since the algorithm encodes one sample at a time, the coding or decoding delay is effectively zero providing for robust, quality audio. In addition, processing frame size and input/output formats is user selectable.



This high performance G.726 Vocoder belongs to GAO’s family of Speech Vocoders. This line also includes G.728 LD-CELP Vocoder which implements the low delay code-excited linear prediction (LD-CELP) speech compression technique specified in the ITU-T standard and provides approximately 4 kHz of speech bandwidth, G.729, G.729A and G.729AB Speech Vocoders which provide toll-quality speech with only moderate processing requirements and delay times and also perform well in the presence of random bit errors.

All GAO Research’s speech software have passed the test vectors specified by the ITU GAO also adheres to stringent quality control procedures, which is reflected in the well structured code, detailed design documentation and well-defined design and test plans. This ensures ease of integration, easy maintenance and a smooth upgrade path for further generation customer products.

About GAO Research Inc.
GAO Research Inc. (www.GAOResearch.com) is a world-renowned provider of high quality, reliable telecommunications software including embedded modem software, fax modem software, speech codes, and telephony software for a wide range of DSPs and microprocessors.