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Voice coding trends


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Reviwe of latest voice coding trends

Reviwe of latest voice coding trends

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  • 1. Speech Codec Trends Robustness Wideband (HD Voice) Multi-bitrate Fast Forward Your Development
  • 2. Robustness • Based on ▫ Better packet loss concealment ▫ Reduced Inter-frame dependency ▫ Built-in FEC Fast Forward Your Development
  • 3. iLBC • Internet Low Bit rate Codec • Packet loss robust CODEC by GlobalIPSound • CELP based CODEC • 13.3/15.6 kb/s for 20/30ms Frames Fast Forward Your Development
  • 4. iLBC (internet Low Bitrate Codec) • Speech sampled at 8 kHZ, • using a block-independent linear-predictive coding (LPC) algorithm. • Bandwidth 13.867 kbps (52 bytes per 30 ms) • Frame size 20/30 • Complexity and memory requirements are similar to ITU G.729A • Basic Quality is equal to or better than G.729. • Packet loss robustness is significantly better than G.729. • Packet loss concealment - Integrated Fast Forward Your Development
  • 5. GIPS Enhanced G.711 • Enhancement of existing standard (G.711) • Enables speech quality equal to PSTN/G.711 on impacted networks • Superior packet-loss robustness compared to G.711 • Lower delay than standard solutions when combined with NetEQ • Allows more efficient network provisioning • Use CODEC level FEC Fast Forward Your Development
  • 6. Speex • Open-source patent-free speech codec • CELP (code-excited linear prediction) codec • operating modes: ▫ narrowband (8 kHz sampling rate) 2.15 – 24.6 kb/s delay of 30 ms ▫ wideband (16 kHz sampling rate) 4-44.2 kb/s delay of 34 ms ▫ ultra-wideband (32 kHz sampling rate) • intensity stereo encoding • variable bit rate (VBR) possible • voice activity detection (VAD) Fast Forward Your Development
  • 7. WideBand Codecs Fast Forward Your Development
  • 8. G.722.1 • G.722.1 is a low-bit-rate wideband coder, which codes speech at 24 kbps or 32 kbps. • G.722.1 uses a transform-coding scheme called Modulated Lapped Transform (MLT), with a 20 ms frame size. • The algorithmic delay is 40 ms (20 ms frame size + 20 ms look-ahead). Fast Forward Your Development
  • 9. G.722.1(cont) • Supports all bit rates viz. 16/32 kbps at 16khz sampling rate • Supports Multi-channel capability • Optimized implementation Fast Forward Your Development
  • 10. GIPS iSAC™ • Packet size is 30 or 60 ms, look-ahead 3 ms • No inter-frame dependency => improved robustness • Variable bit rate codec with source control adaptation as well as external control • The user can set a target bit rate or iSAC can adapt itself using a bandwidth estimator and in-band signaling to utilize the available bandwidth. • Complexity similar to G.722.2 Fast Forward Your Development
  • 11. GIPS iPCM-wb • Wideband codec enabling better-than PSTN voice quality ▫ Supports increasing adaption of 16 kHz sampled voice communications for richer voice communication experience Benefits • Higher basic speech quality than current standards, such as G.722.1 and G.722.2 • Packet-loss robustness that exceeds current standards Fast Forward Your Development
  • 12. GIPS Codecs • Narrowband codecs ▫ GIPS Enhanced G.711 TM ▫ iLBC Freeware TM • Wideband codecs ▫ GIPS iPCM-wb TM ▫ GIPS iSAC TM Fast Forward Your Development
  • 13. Test yourself - 2 1. What are the main three voice coding trends? 2. Provide a codec example for each category Fast Forward Your Development
  • 14. DSP-IP Contact information For Course materials licensing & lecture request contact: Adi Yakov Training and Courses Manager adi@dsp- +972-9-8651933 972- For projects development services contact: Alona Ashkenazi Technology Management Services : alona@dsp- +972-9-8850956 972- www.dsp-ip. Mail : info@dsp-ip. Phone: 972- 8850956, Phone: +972-9-8850956, Fax : +972-50- 8962910 972-50- Fast Forward Your Development