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  • iLBC codec + enhancement Standardization activity (wireless 3GPP, Wideband AMR,..) ITU standard process (circuit switched). Bit exact fixed point standard – leads to IPR problems people today no possibility to differentiation, guarantees a certain quality Internet model – free core in the codec, open standard, the best implementation (companies take IPR on implementations but this more flexible) Interoperability/lower rate (differentiation on implementation and enhancement), minimum performance Codec need footprint (picture) (limited number of codecs will survive) Feature – what kind of codecs are required? End-to-end, PSTN included need to aim for higher than mobile quality. Must be able to handle public internet (robustness, latency) – picture (PSTN, Managed network, Internet) Summary slide: Need to do it right (cannot change all the time)  internet model Handles everything including (all kinds of networks)
  • Question of managing growth… Current voice technology very sensitive to congestion Why? Well let’s go back to the FedEx & UPS analogy
  • Result is: Graceful degradation of sound quality when network is congested
  • We have done it! We have proven that t can be done. Allowing for superior/hifi real-time sound over the public internet!
  • iLBC codec + enhancement Standardization activity (wireless 3GPP, Wideband AMR,..) ITU standard process (circuit switched). Bit exact fixed point standard – leads to IPR problems people today no possibility to differentiation, guarantees a certain quality Internet model – free core in the codec, open standard, the best implementation (companies take IPR on implementations but this more flexible) Interoperability/lower rate (differentiation on implementation and enhancement), minimum performance Codec need footprint (picture) (limited number of codecs will survive) Feature – what kind of codecs are required? End-to-end, PSTN included need to aim for higher than mobile quality. Must be able to handle public internet (robustness, latency) – picture (PSTN, Managed network, Internet) Summary slide: Need to do it right (cannot change all the time)  internet model Handles everything including (all kinds of networks)
  • Changed the word saving with gain and added “ approx. 30-60ms compared to traditional jitter buffers”. If you would like to change it back please feel free to do so. iLBC codec + enhancement Standardization activity (wireless 3GPP, Wideband AMR,..) ITU standard process (circuit switched). Bit exact fixed point standard – leads to IPR problems people today no possibility to differentiation, guarantees a certain quality Internet model – free core in the codec, open standard, the best implementation (companies take IPR on implementations but this more flexible) Interoperability/lower rate (differentiation on implementation and enhancement), minimum performance Codec need footprint (picture) (limited number of codecs will survive) Feature – what kind of codecs are required? End-to-end, PSTN included need to aim for higher than mobile quality. Must be able to handle public internet (robustness, latency) – picture (PSTN, Managed network, Internet) Summary slide: Need to do it right (cannot change all the time)  internet model Handles everything including (all kinds of networks)

Transcript

  • 1. Speech Coders – a VoIP perspective Roar Hagen CTO SIP/email: roar.hagen@globalipsound.com
  • 2. Agenda
    • Speech Coders – a VoIP perspective
    • Demo
    • Q&A
  • 3. QoS – (endpoints) status ”A lot of talk, ... but not much work”
    • Year after year the same story
    • More then 3000 papers since 1984
    • Limited ToS support at the end points
  • 4. QoS – status Industry’s perspective quality concerns unproven technology PSTN works fine too busy to switch not compelling economics 0 10 20 30 40 50 60 percentage of respondents source: Forrester Research/AT&T (2000)
  • 5. Background - Diverse Environment PSTN Managed network Wireless Public Internet Managed network Next generation codecs should address the needs of all applications [ ]
  • 6. Packet Loss San Francisco – Hong Kong
  • 7. Jitter San Francisco – Hong Kong
  • 8. Homg Kong to China VoIP Call
  • 9. Wireless VoIP – The Big Unknown ? LAN 2G/2.5G WLAN Bluetooth 3G Vehicle Walk Fixed Mbps 100 10 1 0.1 Mobility
  • 10. Approach
    • We need holistic view/approach for both
    • Horizontal (end-to-end) perspective
    • Vertical (top-down) perspective
  • 11. Vertical (Top Down) Perspective Physical Link MLPPP/FR/ATM AAL1 Network IP/WFQ/IP-prec Transport RTP/UDP/RSVP Session SIP/H.323 Presentation Speech Codecs/…
  • 12. VoIP Aspirations
    • IP innovation rather than PSTN replication
    • New features and services through voice and data convergence
    • End-to-end IP
    • Better than PSTN sound quality
  • 13. Current speech processing technology not designed for packet switched environments * M EAN O PINION S CORE C ONGESTED N ETWORK O VERPROVISIONED N ETWORK MOS = U SER E XPERIENCE “ F ALL O FF A C LIFF” s hape of curve forces over provisioning
  • 14. … congestion related VoIP QoS problems can be solved without over provisioning … * M EAN O PINION S CORE C ONGESTED N ETWORK O VERPROVISIONED N ETWORK MOS = U SER E XPERIENCE O perate A T and A BOVE congestion point without customer knowing
  • 15. Matching PSTN Quality Telephony bandwidth speech test result S OURCE L OCKHEED M ARTIN GLOBAL T ELECOMMUNICATION (COMSAT) 5 4.5 4.0 3.5 3.0 2.5 2.0 1.5 1.0 N ETWORK C ONDITION (% P ACKET L OSS) MOS GIPS iPCM™-wb+ GIPS NetEQ™-wb G.722+ GIPS NetEQ™-wb G.722.1 Source + no PLC Better Than PSTN Quality Wideband speech 0% 5% 10% 15% 20% 25% 5 4.5 4.0 3.5 3.0 2.5 2.0 1.5 1.0 MOS N ETWORK C ONDITION (% P ACKET L OSS) narrow band sound quality equal to PSTN wide band sound quality GIPS Ehanced G.711+ GIPS NetEQ™ G.711+GIPS NetEQ™ G.711+ITU PLC G.729A G.711+No PLC 0% 5% 30% 10% 15% 25% 20%
  • 16. Jitter Buffer/PLC Enhancements Source: Lockheed Martin Global Telecommunications (COMSAT)
  • 17. Delay gain with NetEQ™ approx. 30-60ms compared to traditional jitter buffers Adaptive jitter buffer Jitter Fixed jitter buffer NetEQ™ 140 120 20 80 100 40 60 0 0 200 400 600 800 1000 1200 1400 1600 1800 2000 Packet number Delay (ms)
  • 18. The NextGen Speech Codec Ideal
    • Need one concept that will work for a long time
      • footprint importance
    • Need to handle large diversity of transport network
      • low rate
      • high quality, high rate
      • packet loss
      • jitter
      • low delay
    • Manageable IPR situation
    • Signal Robustness
      • speech
      • music
    • Suitable for variety of applications, e.g. IP video-conferencing
  • 19. 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 30 ms (support for 20 ms in the next revision)
    • 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 example solution
  • 20. MOS Results Source: Dynastat Inc.
  • 21. iLBC - IETF work
    • IETF deliverables, submitted during February ‘02:
      • iLBC codec specification draft - experimental standards track
      • iLBC RTP Payload Profile - regular standards track (AVT)
      • Statement about IPRs in iLBC and its “freeware nature”
    • MOS results submission to the AVT mailing list during March ‘02
  • 22. Why iLBC !?
    • Current low bit rate codecs: ITU G.729, G.723.1, GSM-EFR, and 3GPP-AMR were developed for circuit switched & wireless telephony and are all based on the CELP (Code Excited Linear Prediction) paradigm.
    • CELP coders are stateful, they have memory, error propagation results from lost or delayed packets.
    • iLBC treats every packet individually, making it suitable for packet communications.
  • 23. More information
    • Coming Soon - web site www.ilbcfreeware.org with:
      • Info about initiative
      • Info about codec
      • Latest iLBC IETF drafts (spec and payload format)
      • Latest iLBC float point Source code
      • FAQ list
    • IETF drafts:
      • draft-andersen-ilbc-00.txt - codec spec (exper. stds track)
      • draft-duric-rtp-ilbc-00.txt - RTP payload profile (AVT group)
    • Web site www.globalipsound.com
    • Free demo SIP client available, please request at:
    • SIP/email: [email_address]
  • 24. Summary
    • Current speech coding technology not suited for VoIP
    • VoIP opens possibilities
      • Move quality exprience to the next level with wideband coders
    • NGN will not be NGN unless we move step forward on all of its fields
    • iLBC – internet Low Bit Rate Codec
      • Provide an open standard ”the Internet way ” for coder
  • 25. Demo