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Codec requirements update

Codec requirements update. Michael Knappe Co-chair, codec WG. Codec requirements. Current version draft-ietf-codec-requirements-00 , an informational doc Jean-Marc Valin and Koen Vos are editors

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Codec requirements update

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  1. Codec requirements update Michael Knappe Co-chair, codec WG Michael Knappe IETF 77

  2. Codec requirements • Current version draft-ietf-codec-requirements-00, an informational doc • Jean-Marc Valin and Koen Vos are editors • Action from March was to further explore and clarify a number of codec parameters and design choices • Goal today: achieve consensus on a number of parameters / design choices, use as basis for update edits to the codec requirements Michael Knappe IETF 77

  3. Discussion points • Sample rates • 8, 16, 24, 32, 48 kHz – which, and how selected? • Will each sample rate be treated as a separate codec as far as SDP is concerned (IIAC8, IIAC16, IIAC48, etc) • What upper bound(s) for bit rates? • Sample rate layering? • Operational modes / variants • Bit exact fixed point / lower complexity mode for constrained endpoints DESIRED • Joint stereo? Michael Knappe IETF 77

  4. Discussion points • Latency • Shall we • Offer ‘low-delay’ mode (eg 5 ms) DESIRED • Packet loss concealment • required as part of the codec package? YES • Performance goals for PLC? INFORMATIVE • ‘Upgradeable’ via bit-compatible modularity? YES • Integration with VAD/CNG? DESIRED Michael Knappe IETF 77

  5. Backup / reference slides Michael Knappe IETF 77

  6. VoIP transmission PLC / ComfortNoise VAD Decode Encode TD EC EC Jitter buffer Synchronous Synchronous Asynchronous Michael Knappe IETF 77

  7. Audio Transmission Useful comparisons: AM radio is limited to 5000 Hz audio FM radio is limited to 15,000 Hz audio CD is limited to 20,000 Hz audio Speed of sound in air: 343 m/s (approx 3 ms/m) Michael Knappe IETF 77

  8. Audio frequencies http://www.podcomplex.com/images/podcomplex-frequency-overview-chart.gif Michael Knappe IETF 77

  9. Application Drivers Content: even traditional phone calls handle signal types other than speech (e.g.music-on-hold), as a baseline we must assume non-specific audio content Other useful features: packet loss concealment, quality and bandwidth layering, joint multi-channel encoding Michael Knappe IETF 77

  10. Narrowband matrix (8 kHz fs) Sources: http://en.wikipedia.org/wiki/Comparison_of_audio_formats, Cable Labs PKT-SP-CODEC-MEDIA-I08-100120 Michael Knappe IETF 77

  11. Wideband + Michael Knappe IETF 77

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