Re: [codec] #16: Multicast?
Jean-Marc Valin <jean-marc.valin@usherbrooke.ca> Fri, 23 April 2010 04:04 UTC
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Date: Fri, 23 Apr 2010 00:04:32 -0400
From: Jean-Marc Valin <jean-marc.valin@usherbrooke.ca>
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To: "Raymond (Juin-Hwey) Chen" <rchen@broadcom.com>
References: <062.7439ee5d5fd36480e73548f37cb10207@tools.ietf.org> <3E1D8AD1-B28F-41C5-81C6-478A15432224@csperkins.org> <D6C2F445-BE4A-4571-A56D-8712C16887F1@americafree.tv> <C0347188-A2A1-4681-9F1E-0D2ECC4BDB3B@csperkins.org> <u2x6e9223711004210733g823b4777y404b02330c49dec1@mail.gmail.com> <000001cae173$dba012f0$92e038d0$@de> <r2q6e9223711004211010gfdee1a70q972e8239fef10435@mail.gmail.com> <001101cae177$e8aa6780$b9ff3680$@de> <t2t6e9223711004211119i6b107798pa01fc4b1d33debf1@mail.gmail.com> <002d01cae188$a330b2c0$e9921840$@de> <CB68DF4CFBEF4942881AD37AE1A7E8C74AB3F4A017@IRVEXCHCCR01.corp.ad.broadcom.com>
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Cc: "codec@ietf.org" <codec@ietf.org>, 'stephen botzko' <stephen.botzko@gmail.com>
Subject: Re: [codec] #16: Multicast?
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Hi, See me comments below. > [Raymond]: High quality is a given, but I would like to emphasize the > importance of low latency. > > (1) It is well-known that the longer the latency, the lower the > perceived quality of the communication link. The E-model in the ITU-T > Recommendation G.107 models such communication quality in MOS_cqe, > which among other things depends on the so-called “delay impairment > factor” /Id/. Basically, MOS_cqe is a monotonically decreasing > function of increasing latency, and beyond about 150 ms one-way delay, > the perceived quality of the communication link drops rapidly with > further delay increase. > As the author of CELT, I obviously agree that latency is an important aspect for this codec :-) That being said, I tend to say that 20 ms is still the most widely used frame size, so we might as well optimise for that. This is not really a problem because as the frame size goes down, the overhead of the IP/UDP/RTP headers go up, so the codec bit-rate becomes a bit less of an issue. For example, with 5 ms frames, we would already be sending 64 kb/s worth of headers (excluding the link layer), so we might as well spend about as many bits on the actual payload as we spend on the headers. And with 64 kb/s of payload, we can actually have high-quality full-band audio. > 1) If a conference bridge has to decode a large number of voice > channels, mix, and re-encode, and if compressed-domain mixing cannot > be done (which is usually the case), then it is important to keep the > decoder complexity low. Definitely agree here. The decoder complexity is very important. Not only because of mixing issue, but also because the decoder is generally not allowed to take shortcuts to save on complexity (unlike the encoder). As for compressed-domain mixing, as you say it is not always available, but *if* we can do it (even if only partially), then that can result in a "free" reduction in decoder complexity for mixing. > 2) In topology b) of your other email > (IPend-to-transcoding_gateway-to-PSTNend), the transcoding gateway, or > VoIP gateway, often has to encode and decode thousands of voice > channels in a single box, so not only the computational complexity, > but also the per-instance RAM size requirement of the codec become > very important for achieving high channel density in the gateway. > Agreed here, although I would say that per-instance RAM -- as long as it's reasonable -- is probably a bit less important than complexity. > 3) Many telephone terminal devices at the edge of the Internet use > embedded processors with limited processing power, and the processors > also have to handle many tasks other than speech coding. If the IETF > codec complexity is too high, some of such devices may not have > sufficient processing power to run it. Even if the codec can fit, some > battery-powered mobile devices may prefer to run a lower-complexity > codec to reduce power consumption and battery drain. For example, even > if you make a Internet phone call from a computer, you may like the > convenience of using a Bluetooth headset that allows you to walk > around a bit and have hands-free operation. Currently most Bluetooth > headsets have small form factors with a tiny battery. This puts a > severe constraint on power consumption. Bluetooth headset chips > typically have very limited processing capability, and it has to > handle many other tasks such as echo cancellation and noise reduction. > There is just not enough processing power to handle a relatively > high-complexity codec. Most BT headsets today relies on the extremely > low-complexity, hardware-based CVSD codec at 64 kb/s to transmit > narrowband voice, but CVSD has audible coding noise, so it degrades > the overall audio quality. If the IETF codec has low enough > complexity, it would be possible to directly encode and decode the > IETF codec bit-stream at the BT headset, thus avoiding the quality > degradation of CVSD transcoding. > Any idea what the complexity requirements would be for this use-case to be possible? Cheers, Jean-Marc
- [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? 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? Raymond (Juin-Hwey) Chen
- 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] #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] Thresholds and delay. stephen botzko
- 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] #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... Herve Taddei
- 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