Complete Communications Engineering

ITU G.711.1 Software

VOCAL offers the G.711.1 codec software as a standalone algorithm, as part of a modular software library suite, as well as with a VoIP stack.


G.711 is the most utilized codec for VoIP communications. ITU G.711.1 is a backwards compatible enhancement of the G.711 codec. G.711.1 is a scalable codec with four operating modes consisting of three layers of encoding. The base layer is the G.711 A-law/mu-law 64kbps codec. The additional layers provide improved quality and intelligibility of G.711. The first enhancement layer uses an adaptive perceptual filter to improve on the quantization of the narrowband base layer. This process adds 16kbps worth of data. The second enhancement layer, uses the upper band of a wideband signal and encodes the data using the Modified Discrete Cosine Transform (MDCT). All modes use the G.711 base layer. Modes R1 and R2a operate on narrowband (8kHz sampling) signals. Mode R1 uses only the base layer and Mode R2a uses the narrowband extension layers resulting in a data rate of 80kbps. Modes R2b and R3 operate on wideband (16kHz sampling) signals. Wideband signals are split into upper and lower 8kHz signals. Mode R2b adds the upper band enhancement layers resulting in a data rate of 80bkps, and Mode R3 adds both lower and upper band enhancements for a data rate of 96kbps. All of modes process frames 5ms of length. The algorithmic latency is 11.875ms.

G711.1 encoder


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supported platforms

VOCAL’s optimized vocoder software is available for the following platforms. Please contact us for specific vocoder supported platforms.

ProcessorsOperating Systems
  • Texas Instruments – C6xx (TMS320C62x, TMS320C64x, TMS320C645x, TMS320C66x, TMS320C67x), DaVinci, OMAP, C5xx (TMS320C54x, TMS320C55x)
  • Analog Devices – Blackfin, ADSP-21xx, TigerSHARC, SHARC
  • PowerPC, PowerQUICC
  • MIPS – MIPS32, MIPS64, MIPS4Kc
  • ARM – ARM7, ARM9, ARM9E, ARM10E, ARM11, StrongARM, ARMCortex-A8/A9/A15/A3x/A5x/A7x, Cortex-M3/M4/M7/M33
  • Intel / AMD – x86, x64 (both 32 and 64 bit modes)
  • Linux, uClinux, BSD, Unix
  • Microsoft Windows ACM / RTC / CE / Mobile
  • Apple iOS / iPhone / iPad & MacOS
  • Google Android
  • Green Hills Integrity
  • Micrium μCOS
  • Symbian
  • Wind River VxWorks
  • eCOS / eCOSPro