The document discusses audio codecs and the SILK codec developed by Skype. It provides information on sample rates, bandwidths, and common audio codecs used for voice calls. It then summarizes the features of SILK, including its wideband capabilities, quality, efficiency, and licensing as Skype's default codec. Reviews are shown that praise SILK's improved audio quality compared to prior codecs.

2. Who Cares About Codecs? Jonathan Christensen eComm 2009

3. 80 – 14,000 Hz

4. 80 – 14,000 Hz

6. 400 – 3,400Hz

7. End to End Electronics

10. The Digital Era PCM – G.711 8kHz Samples (.125MS) Each Sample is ~13 bits Encoded to 8bits 3.4kHz of Bandwidth

14. Wideband Audio 16kHz Sample Rate ~8kHz Bandwidth Or 50 – 7000Hz.. New, Open Transport Layer

16. NEW! Super Wideband More Samples More Fidelity The Next Building Block Voice 2.0

17. ;-)

18. ;-(

19. ;-) 50 – 12,000Hz

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

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: https://developer.skype.com/silk

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.

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.

33. Supporting Partners

35. Q&A