Jonathan Christensen's Presentation at eComm 2009

Who Cares About Codecs? Jonathan Christensen eComm 2009

80 – 14,000 Hz

400 – 3,400Hz

End to End Electronics

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

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

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

;-) 50 – 12,000Hz

Demo
Female and Male speech
Each encoded 3 times
PSTN quality
Wideband
Super wideband

Recognize, Decipher, Enjoy
Recognize who is talking (esp. in a conference)
Decipher tricky sounds
Are we “failing” or “sailing”?
Hear through doubletalk
Decode background noise
Understand faint talkers
Its like being there…..

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

Choices?
AMR-WB (3GPP for IMS)
Efficient, High Quality
Only 7kHz (Wideband-ish)
Royalty based licensing
SPEEX
OK quality, reasonable efficiency
Open source, free
RTAudio (Microsoft)
OK quality
Microsoft licensing

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

About SILK
Designed and developed by Skype Audio team
State of the art internet speech coder
Scalable / variable bit rate from 6 – 40kbps
Portable (Fixed Point ANSI C)
Lightweight (Low- bit rate, delay, CPU, memory, code size)
Robust to jitter and packet loss
Flexible / multiple modes
8kHz Narrowband for PSTN gateways and low end devices
16kHz Wideband for PC applications and smart devices
24kHz Super-Wideband - a new standard for speech quality

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.

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.

Supporting Partners

What bloggers are saying…
"The new, efficient Silk audio codec produces class-leading sound for video and voice, earning Skype our Editors' Choice for video calling."
http://www.pcmag.com/article2/0%2C2817%2C2341413%2C00.asp
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.
http://saunderslog.com/2009/02/04/skype-40-audio-smooth-as-silk/

http://blogs.voxeo.com	249
http://ecommmedia.com	35
http://ecomm.ec	10
http://blog.ecomm.ec	6
http://www.slideshare.net	6
http://email.secureserver.net	1
http://translate.googleusercontent.com	1

Jonathan Christensen's Presentation at eComm 2009

by eCommConf on Mar 13, 2009

Accessibility

Categories

Upload Details

Usage Rights

7 Embeds 308

Statistics

Jonathan Christensen’s Presentation at eComm 2009 — Presentation Transcript