What’s new in Wideband Audio?

1. What’s new in Wideband Audio?

2. Wideband Audio • VoIP is indeed a disruptive technology, but has it changed the life of the average consumer? • Cost? • Quality? • Features? • Wideband Audio codecs and improved handling of music could soon change this dynamic • Let’s discuss • Technology behind the codecs • Real-world implementations

3. Telecom Audio Spectrum • Human voice: 80 Hz to 14,00Hz • Narrowband: 8 kHz sampling (300-3400 Hz bandwidth) • Used in PSTN, mostly intelligible • Wideband: 16 kHz sampling (50-7000 Hz bandwidth) • Used in VoIP

4. Wideband Audio? • Captures significantly more speech information • Significant improvement in speech quality over traditional PSTN • Improved naturalness & presence below 200Hz • Increased intelligibility above 3,400Hz • Improves user experience and satisfaction • New applications – voice recognition • Customer retention • Fewer misunderstandings

5. Wideband Enablers • Telecom was about minimizing transport cost • Now about differentiation and enhancing the user experience • Access bandwidth was limited • Broadband access now a reality: high bandwidth delivered at low cost • 1 - 10 Mbits/s • Cost of WB is similar to NB @ 64kbps • Endpoints and Network were not wideband capable Now: • VoIP, Wideband DECT, Skype, Microsoft OCS • Wireless deployments: wideband, music codecs • Private / corporate networks, Tandem Free Operation (TFO), Wideband extension, Wideband SLICS

6. The Technology

7. Lossy Codec Classes • Speech communication codecs (G.72X, AMR et.al) • Designed for “real-time” speech, music handled poorly • Low sampling rate (8-16KHz), low fidelity • Low-medium delay (10-30 ms) • Mostly time-domain (CELP is the most popular) • Music codecs (MP3, AAC, Vorbis) • Can encode any signal (not optimal for speech) – designed for entertainment • Up to 48 kHz sampling rate (full bandwidth), high fidelity (“CD-quality” • High delay (>100 ms) • Mostly frequency domain (MDCT-based)

8. Speech Codec Spectrum ApplicationsDeployed Bandwidth Example Codec Bandwidth More than 15KhzFull Band (20Khz) AAC-LD Presence(Video Conf) 14KhzSuper Wideband G.722.1C (Siren14), SILK VoIP, Audio Conf 7KhzWideband G.722.2 (AMR-WB), SVOPC BB VoIP & Audio Chat 3.5KhzNarrowband G.729, G.723.1G.711, iSAC PSTN &VoIP

9. ITU and 3GPP codec roadmap Super -wideband EV-VBR 2008 G.722.2 AMR-WB 2002 G.729.1 2007 G.722 1988 G.722.1 1999 wideband AMR-NB 1999 GSM-FR 1987 G.728 1992 GSM-HR 1994 GSM-EFR 1995 G.726 1984 narrowband G.729 1995 Years ITU 3GPP 3GPP & ITU Legend:

10. Embedded Speech Codecs • ITU-Super WB • Provides extended bandwidth and stereo capabilities • 16 KHz audible bandwidth • Stereo extension • Generic extension applicable to wideband codecs e.g.. ITU G.729.1 & EV-VBR • 3GPP-EPS (evolved packet system) (aka LTE) • ITU EV-VBR is well positioned to meet future EPS requirements • Interoperable with 3GPP AMR-WB. • Open Codecs • Speex (4 to 42Kbps) • Royalty free but limited to non patented techniques (ACELP for example)

11. Music Codecs • MPEG-1 Layer III (aka MP3) • Built on top of Layers I and II • First-generation, very inefficient • AAC • Second generation, much better than MP3 • Flexible, kitchen-sink type of approach • Tons of tools and partially incompatible profiles • Variants: AAC-LC, AAC-LD, AAC-HE, ... • Vorbis • Second-generation, similar quality to AAC • Open-source, royalty-free (Xiph.Org Foundation)

12. Future of codecs • Improving quality • Super-wideband, coding of music • The gap between speech and music codecs is closing • AMR-WB+, G.722.1x moving to music, higher quality • AAC-LD moving to lower delay • Reducing delay • Increasing robustness • Shift from bit-error robustness to packet loss robustness

13. Improved Music Handling • Background music is poorly handled • Most speech codecs (AMR-NB, G.729, AMR-WB, Speex etc) are derivatives based on CELP • CELP makes assumptions that are only valid for speech (and single-note music) • CELP does not perform well on music – especially at low bit-rate • Music codecs are not suitable for speech

14. Improved Music Handling How do you improve the handling of background music? • Three strategies: • Increase the bit-rate • Dual-mode codecs (e.g. AMR-WB+) • Use non-CELP codecs (AAC-LD, G.722.1x, G.711.1, CELT, …)

15. Wideband Extension (WEx) as an interim solution How do you provide a wideband experience when linking a wideband-capable client to the PSTN? • Current solution: up-sample the narrowband speech to 16 kHz • Better solution: Create wideband “artificially” from the narrowband speech • Support becoming available • WEx capable handsets (Philips for example) • WEx enabled Media Gateway (Vocallo for example)

16. The Implementations a.k.a The Role of the Media Gateway

17. Wideband VoIP DECT - France Telecom Mobile Platform IAD Access Platform IP Network TDM Network IMS GW DLC Access Platform IAD

18. Wide Band Extension (WBE) Mobile Platform Wide Band Extension Expand the signal to create impression of wideband. AEC ANR NLE IP Network WBE IMS GW LEC IP/DLC TDM Network Access Platform DLC IAD

19. Wideband Lite Acoustic Echo Canceller acts as a complement to badly designed handset AEC Wideband Natural Level Enhancement, uses info from intensity of the voice and SNR to compensate for loud environment of the talker ANR NLE Wideband Adaptive Noise Reduction reduces noise of mobile handset environment. Improving the User Experience Mobile Platform IP Network IMS GW IP/DLC TDM Network DLC IAD Access Platform

20. The role of the MGW • When selecting MGW solutions: • Don’t just look for checklist of codecs! • Look for solutions that provide wideband extension, wideband ECAN, ANR, etc. • Select solutions that incur low latency when transcoding IP-to-IP communications

21. Summary • Clear benefit to the users • Skype changed expectation levels • Technology enablers already in place • VoIP deployment • CODECS • WB-enabled end-points and MGWs available