Re: [codec] #16: Multicast?
"Raymond (Juin-Hwey) Chen" <rchen@broadcom.com> Mon, 26 April 2010 21:02 UTC
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From: "Raymond (Juin-Hwey) Chen" <rchen@broadcom.com>
To: Mikael Abrahamsson <swmike@swm.pp.se>
Date: Mon, 26 Apr 2010 14:02:18 -0700
Thread-Topic: [codec] #16: Multicast?
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Cc: "codec@ietf.org" <codec@ietf.org>
Subject: Re: [codec] #16: Multicast?
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Hi Mikael, Thanks for sharing your experience using a BT headset for Skype calls. I think part of the quality degradation that you experienced was due to the reduction of the audio bandwidth to narrowband (8 kHz sampling, 3.4 kHz bandwidth), and another part of the degradation was due to the audible coding noise of the CVSD codec, a 40-year-old coding technology first proposed in 1970. If a high-quality, low-complexity, wider bandwidth IETF codec mode can be implemented in Skype and the Bluetooth headset to avoid the CVSD transcoding (together with wideband upgrade of the transducers and audio path in the BT headset, of course), then not only will you get much better speech quality in your Skype calls than what you have experienced, but also you will get a lower latency. This is because transcoding between the Skype codec and CVSD not only accumulates the coding distortion of the two codecs, but also accumulates the coding delays. Although CVSD is a sample-by-sample codec, BT headsets still transmit the CVSD bit-stream in 3.75 ms or 7.5 ms packets, and they can potentially add a one-way delay up to 20 ~ 25 ms through the Bluetooth headset (the exact delay depends on the implementation). While we were discussing whether a 5 ms packet size can even be considered, for many years Bluetooth headsets have been using an even smaller 3.75 ms packet size. Best Regards, Raymond -----Original Message----- From: Mikael Abrahamsson [mailto:swmike@swm.pp.se] Sent: Sunday, April 25, 2010 1:06 AM To: Raymond (Juin-Hwey) Chen Cc: Koen Vos; codec@ietf.org Subject: Re: [codec] #16: Multicast? On Sat, 24 Apr 2010, Raymond (Juin-Hwey) Chen wrote: > (7) Already a lot of people are used to using Bluetooth headsets to make > phone calls today. If they have a choice, many of these people will > also want to use Bluetooth headsets to make Internet phone calls, not > only through computers, but also through smart phones connected to WiFi > or cellular networks. As more and more states and countries pass laws > to ban the use of cell phones that are not in hands-free mode while > driving, the number of Bluetooth headset users will only increase with > time, and many of them will want to make Internet-based phone calls. I purchased a BT headset with the anticipation of using it with my computer to make Skype calls. I tried it, but the sound quality when doing bidirectional audio (whatever that mode is called) is not good enough, it worsens the "skype IP" call quality. I agree that the use case is interesting, but as long as BT sound quality is what it is, it's really only the "low end" type sound quality we're talking about. But yes, I make skype IP calls with my Nokia N900 using BT sometimes, so the use case example is definitely valid. -- Mikael Abrahamsson email: swmike@swm.pp.se
- [codec] #16: Multicast? codec issue tracker
- Re: [codec] #16: Multicast? Colin Perkins
- Re: [codec] #16: Multicast? Christian Hoene
- Re: [codec] #16: Multicast? Marshall Eubanks
- Re: [codec] #16: Multicast? stephen botzko
- Re: [codec] #16: Multicast? Colin Perkins
- Re: [codec] #16: Multicast? Colin Perkins
- Re: [codec] #16: Multicast? stephen botzko
- Re: [codec] #16: Multicast? Christian Hoene
- Re: [codec] #16: Multicast? stephen botzko
- Re: [codec] #16: Multicast? Marshall Eubanks
- Re: [codec] #16: Multicast? Christian Hoene
- Re: [codec] #16: Multicast? stephen botzko
- Re: [codec] #16: Multicast? Christian Hoene
- Re: [codec] #16: Multicast? Raymond (Juin-Hwey) Chen
- Re: [codec] #16: Multicast? Jean-Marc Valin
- Re: [codec] #16: Multicast? Koen Vos
- Re: [codec] #16: Multicast? Raymond (Juin-Hwey) Chen
- Re: [codec] #16: Multicast? Mikael Abrahamsson
- Re: [codec] #16: Multicast? Jean-Marc Valin
- Re: [codec] #16: Multicast? Raymond (Juin-Hwey) Chen
- Re: [codec] #16: Multicast? Koen Vos
- Re: [codec] #16: Multicast? Raymond (Juin-Hwey) Chen
- Re: [codec] #16: Multicast? stephen botzko
- Re: [codec] #16: Multicast? Raymond (Juin-Hwey) Chen
- Re: [codec] #16: Multicast? Koen Vos
- Re: [codec] #16: Multicast? Raymond (Juin-Hwey) Chen
- Re: [codec] #16: Multicast? Mikael Abrahamsson
- Re: [codec] #16: Multicast? Raymond (Juin-Hwey) Chen
- Re: [codec] #16: Multicast? Raymond (Juin-Hwey) Chen
- Re: [codec] #16: Multicast? Mikael Abrahamsson
- Re: [codec] #16: Multicast? (Bluetooth) Koen Vos
- Re: [codec] #16: Multicast? Koen Vos
- Re: [codec] #16: Multicast? stephen botzko
- Re: [codec] #16: Multicast? Raymond (Juin-Hwey) Chen
- Re: [codec] #16: Multicast? Raymond (Juin-Hwey) Chen
- Re: [codec] #16: Multicast? Raymond (Juin-Hwey) Chen
- Re: [codec] #16: Multicast? Koen Vos
- Re: [codec] #16: Multicast? (Bluetooth) Raymond (Juin-Hwey) Chen
- Re: [codec] #16: Multicast? (Bluetooth) stephen botzko
- Re: [codec] #16: Multicast? Christian Hoene
- Re: [codec] #16: Multicast? Raymond (Juin-Hwey) Chen
- Re: [codec] #16: Multicast? Christian Hoene
- Re: [codec] #16: Multicast? Christian Hoene
- Re: [codec] #16: Multicast? (USB) Roni Even
- Re: [codec] #16: Multicast? codec issue tracker
- Re: [codec] #16: Multicast? stephen botzko
- Re: [codec] #16: Multicast? Cullen Jennings
- Re: [codec] #16: Multicast? Mikael Abrahamsson
- Re: [codec] #16: Multicast? Koen Vos
- Re: [codec] #16: Multicast? (Bluetooth) Koen Vos
- Re: [codec] #16: Multicast? stephen botzko
- Re: [codec] #16: Multicast? Christian Hoene
- Re: [codec] #19: How large is the frame size depe… Christian Hoene
- Re: [codec] #19: How large is the frame size depe… stephen botzko
- Re: [codec] #16: Multicast? Raymond (Juin-Hwey) Chen
- Re: [codec] #19: How large is the frame size depe… Raymond (Juin-Hwey) Chen
- Re: [codec] #16: Multicast? Raymond (Juin-Hwey) Chen
- Re: [codec] #16: Multicast? (Bluetooth) Raymond (Juin-Hwey) Chen
- Re: [codec] #16: Multicast? Raymond (Juin-Hwey) Chen
- Re: [codec] #16: Multicast? stephen botzko
- Re: [codec] #16: Multicast? Raymond (Juin-Hwey) Chen
- Re: [codec] #16: Multicast? stephen botzko
- Re: [codec] #16: Multicast? Raymond (Juin-Hwey) Chen
- Re: [codec] #16: Multicast? Koen Vos
- Re: [codec] #16: Multicast? Christian Hoene
- Re: [codec] #16: Multicast? Gregory Maxwell
- Re: [codec] #16: Multicast? Raymond (Juin-Hwey) Chen
- Re: [codec] #16: Multicast? Koen Vos
- Re: [codec] #16: Multicast? Raymond (Juin-Hwey) Chen
- Re: [codec] #16: Multicast? Koen Vos
- Re: [codec] #16: Multicast? Raymond (Juin-Hwey) Chen
- Re: [codec] #16: Multicast? Raymond (Juin-Hwey) Chen
- Re: [codec] #16: Multicast? Koen Vos
- Re: [codec] #16: Multicast? Koen Vos
- Re: [codec] #16: Multicast? Benjamin M. Schwartz
- Re: [codec] #16: Multicast? Raymond (Juin-Hwey) Chen
- Re: [codec] Thresholds and delay. stephen botzko
- Re: [codec] #16: Multicast? Raymond (Juin-Hwey) Chen
- Re: [codec] #16: Multicast? Kevin P. Fleming
- Re: [codec] #16: Multicast? Raymond (Juin-Hwey) Chen
- Re: [codec] #16: Multicast? Jean-Marc Valin
- Re: [codec] #16: Multicast? Raymond (Juin-Hwey) Chen
- Re: [codec] #16: Multicast? Jean-Marc Valin
- Re: [codec] #16: Multicast? Raymond (Juin-Hwey) Chen
- Re: [codec] #16: Multicast? Raymond (Juin-Hwey) Chen
- Re: [codec] #16: Multicast? Christian Hoene
- Re: [codec] #16: Multicast? Koen Vos
- Re: [codec] #16: Multicast? Christian Hoene
- Re: [codec] #16: Multicast? Ben Schwartz
- Re: [codec] #16: Multicast? Marshall Eubanks
- Re: [codec] #16: Multicast? Brian Rosen
- Re: [codec] #16: Multicast? Christian Hoene
- Re: [codec] #16: Multicast? Jean-Marc Valin
- Re: [codec] Thresholds and delay. Ben Schwartz
- Re: [codec] #16: Multicast? Raymond (Juin-Hwey) Chen
- Re: [codec] Thresholds and delay. stephen botzko
- Re: [codec] #16: Multicast? Christian Hoene
- Re: [codec] Thresholds and delay. Ben Schwartz
- Re: [codec] #20: Computational complexity? Raymond (Juin-Hwey) Chen
- Re: [codec] #16: Multicast? Raymond (Juin-Hwey) Chen
- Re: [codec] Thresholds and delay. jari.hagqvist
- Re: [codec] Thresholds and delay. stephen botzko
- Re: [codec] Thresholds and delay. Ben Schwartz
- Re: [codec] Thresholds and delay. Marshall Eubanks
- Re: [codec] #16: Multicast? Cullen Jennings
- Re: [codec] Thresholds and delay. Michael Knappe
- Re: [codec] #16: Multicast? Raymond (Juin-Hwey) Chen
- Re: [codec] #16: Multicast? Koen Vos
- Re: [codec] #16: Delay factor: algorithmic delay … Christian Hoene
- Re: [codec] #16: Delay factor: algorithmic delay … Mikael Abrahamsson
- Re: [codec] #16: Delay factor: algorithmic delay … Roman Shpount
- Re: [codec] #16: Delay factor: algorithmic delay … stephen botzko
- Re: [codec] #16: Multicast? Raymond (Juin-Hwey) Chen
- Re: [codec] #16: Multicast? Cullen Jennings
- Re: [codec] #16: Multicast? Raymond (Juin-Hwey) Chen
- Re: [codec] #16: Multicast? Koen Vos
- Re: [codec] #16: Multicast? Raymond (Juin-Hwey) Chen
- Re: [codec] #16: Multicast? Koen Vos
- Re: [codec] #16: Multicast? Christian Hoene
- Re: [codec] #16: Multicast? Jean-Marc Valin
- Re: [codec] #16: Multicast? Herve Taddei
- Re: [codec] #16: Multicast? Christian Hoene
- Re: [codec] #16: Multicast? Jean-Marc Valin
- Re: [codec] #16: Multicast? Sandy (Alexander) MacInnis
- Re: [codec] #16: Multicast? Christian Hoene
- Re: [codec] #16: Multicast? Raymond (Juin-Hwey) Chen
- Re: [codec] #16: Multicast? Roman Shpount
- Re: [codec] Suggested summary... Herve Taddei
- Re: [codec] #16: Multicast? Herve Taddei
- Re: [codec] #16: Multicast? Cullen Jennings
- [codec] Suggested summary... Christian Hoene
- Re: [codec] Suggested summary... stephen botzko
- Re: [codec] Suggested summary... Herve Taddei
- Re: [codec] Suggested summary... Christian Hoene
- Re: [codec] Suggested summary... Michael Knappe
- Re: [codec] Suggested summary... stephen botzko
- Re: [codec] Suggested summary... Christian Hoene
- Re: [codec] Suggested summary... Christian Hoene
- Re: [codec] Suggested summary... stephen botzko
- Re: [codec] Suggested summary... Raymond (Juin-Hwey) Chen
- Re: [codec] Suggested summary... Christian Hoene
- Re: [codec] Suggested summary... Herve Taddei
- Re: [codec] Suggested summary... Raymond (Juin-Hwey) Chen