Jonathan Christensen's Presentation at eComm 2009


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  • Jonathan Christensen's Presentation at eComm 2009

    1. 2. Who Cares About Codecs? Jonathan Christensen eComm 2009
    2. 3. 80 – 14,000 Hz
    3. 4. 80 – 14,000 Hz
    4. 6. 400 – 3,400Hz
    5. 7. End to End Electronics
    6. 10. The Digital Era PCM – G.711 8kHz Samples (.125MS) Each Sample is ~13 bits Encoded to 8bits 3.4kHz of Bandwidth
    7. 14. Wideband Audio 16kHz Sample Rate ~8kHz Bandwidth Or 50 – 7000Hz.. New, Open Transport Layer
    8. 16. NEW! Super Wideband More Samples More Fidelity The Next Building Block Voice 2.0
    9. 17. ;-)
    10. 18. ;-(
    11. 19. ;-) 50 – 12,000Hz
    12. 20. Demo <ul><li>Female and Male speech </li></ul><ul><li>Each encoded 3 times </li></ul><ul><ul><li>PSTN quality </li></ul></ul><ul><ul><li>Wideband </li></ul></ul><ul><ul><li>Super wideband </li></ul></ul>
    13. 22. Recognize, Decipher, Enjoy <ul><li>Recognize who is talking (esp. in a conference) </li></ul><ul><li>Decipher tricky sounds </li></ul><ul><ul><li>Are we “failing” or “sailing”? </li></ul></ul><ul><ul><li>Hear through doubletalk </li></ul></ul><ul><ul><li>Decode background noise </li></ul></ul><ul><ul><li>Understand faint talkers </li></ul></ul><ul><li>Its like being there….. </li></ul>
    14. 27. G.711, G.722, G.729, iSAC, iLBC, AMR-NB, VMR-WB, SPEEX, G.722.1, GSM Half Rate, AMR-WB G.718, G.719, G.722.2, G.723, G.723.1, G.728, GSM Enhanced Rate, HVXC, FS-1015, FS-1016, ADPCM, RTAudio, iPCM-WB, G.729a, GSM Full Rate, MELP, IMBE, RCELP, VSELP, CELT
    15. 28. Choices? <ul><li>AMR-WB (3GPP for IMS) </li></ul><ul><ul><li>Efficient, High Quality </li></ul></ul><ul><ul><li>Only 7kHz (Wideband-ish) </li></ul></ul><ul><ul><li>Royalty based licensing </li></ul></ul><ul><li>SPEEX </li></ul><ul><ul><li>OK quality, reasonable efficiency </li></ul></ul><ul><ul><li>Open source, free </li></ul></ul><ul><li>RTAudio (Microsoft) </li></ul><ul><ul><li>OK quality </li></ul></ul><ul><ul><li>Microsoft licensing </li></ul></ul>
    16. 29. Announcement SILK Licensing Program Skype will offer SILK royalty free for license by third party developers. SILK is our primary / signature super-wideband audio codec. SILK is now the default audio codec for all Skype-to-Skype audio calls on Skype for Windows (Mac & Linux coming soon) Interested parties can get more information at:
    17. 30. About SILK <ul><li>Designed and developed by Skype Audio team </li></ul><ul><li>State of the art internet speech coder </li></ul><ul><ul><li>Scalable / variable bit rate from 6 – 40kbps </li></ul></ul><ul><ul><li>Portable (Fixed Point ANSI C) </li></ul></ul><ul><ul><li>Lightweight (Low- bit rate, delay, CPU, memory, code size) </li></ul></ul><ul><ul><li>Robust to jitter and packet loss </li></ul></ul><ul><li>Flexible / multiple modes </li></ul><ul><ul><li>8kHz Narrowband for PSTN gateways and low end devices </li></ul></ul><ul><ul><li>16kHz Wideband for PC applications and smart devices </li></ul></ul><ul><ul><li>24kHz Super-Wideband - a new standard for speech quality </li></ul></ul>
    18. 31. Mean Opinion Score (MOS) Results MOS (Mean Opinion Score) listening test was performed by Dynastat, an independent 3 rd party laboratory. Confidence intervals (95%) are +/- 0.1 MOS. All bitrates are measured and averaged over frames containing active speech. All audio signals are Wideband. SILK and Speex were run in the highest complexity mode.
    19. 32. Robust to Jitter & Packet Loss MOS scores for Wideband speech signals at different packet loss rates. All codecs were operated at a bitrate of 18.25 kbps.
    20. 33. Supporting Partners
    21. 34. What bloggers are saying… <ul><li>&quot;The new, efficient  Silk audio codec produces class-leading sound for video and voice, earning  Skype our Editors' Choice for video calling.&quot; </li></ul><ul><li> </li></ul><ul><li>Skype 4.0 is the best Skype yet, bar none…Perhaps the biggest improvement, though, is audio quality .  We all thought that Skype audio was great, right?  Skype’s internally developed SILK codec... A wideband codec that delivers the goods at half the bitrate of prior codecs, SILK makes talking on Skype a pure pleasure … The difference is noticeable, and worth the download alone. </li></ul><ul><li> </li></ul>
    22. 35. Q&A