Re: [codec] #28: Layered bit-stream
"Dmitry Yudin" <Yudin@spiritdsp.com> Thu, 06 May 2010 09:45 UTC
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Date: Thu, 06 May 2010 13:45:15 +0400
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From: Dmitry Yudin <Yudin@spiritdsp.com>
To: Christian Hoene <hoene@uni-tuebingen.de>, Vladimir Sviridenko <vladimirs@spiritdsp.com>, codec-bounces@ietf.org
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Cc: Slava Borilin <Borilin@spiritdsp.com>, codec@ietf.org
Subject: Re: [codec] #28: Layered bit-stream
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Hi Christian, >From application point of view, the layered stream structure allows server manipulate channel bandwidth individually for each user with zero performance overhead. Obviously, conferencing is the most important use-case. > a) First, this use case is a local optimization only. Thus, the must not be standardized. What do you mean exactly? "local optimization" of what? > b) Second, instead of layered coding one can use other ways of tweaking the implementation > performance. For example, if you calculate a 512 FFT do get two 256 FFTs for free. > I bet there are thousand other shortcuts which I am not aware of. How do this interrelates with scalability? Please, explain. Let's return back to the subject: Shall layered coding be supported? - we think "yes", because ... (see my first sentence) Who needs it? - answered Can we drop this requirement? - only if we have real good reasons for it. Do we have them? Best regards, Dmitry -----Original Message----- From: Christian Hoene [mailto:hoene@uni-tuebingen.de] Sent: Wednesday, May 05, 2010 11:02 PM To: Vladimir Sviridenko; codec-bounces@ietf.org Cc: Slava Borilin; Dmitry Yudin; codec@ietf.org Subject: RE: [codec] #28: Layered bit-stream Hi Vladimir, >2/ we think that VoIP and Videoconferencing systems are users of such >codecs. Could you please explain your position a bit? As far as I understand, layered coding helps if multiple streams having the sample content but different rates must be generated. For example, if a conferencing system stream the same audio stream to N users but each users has a different bandwidth. Just encode all layers and drop the higher layers for the low bandwidth users. This approach is easy and efficient and reduce the encoding complexity. The arguments against are simple. a) First, this use case is a local optimization only. Thus, the must not be standardized. b) Second, instead of layered coding one can use other ways of tweaking the implementation performance. For example, if you calculate a 512 FFT do get two 256 FFTs for free. I bet there are thousand other shortcuts which I am not aware of. Thus, I have the opinion that layered coding is not worth the extra bandwidth of 20 or more percentage. It is just good locally but not needed for interoperability. Yours, Christian >Yours, >Vladimir Sviridenko >SPIRIT > >-----Original Message----- >From: codec-bounces@ietf.org [mailto:codec-bounces@ietf.org] On Behalf >Of codec issue tracker >Sent: Sunday, May 02, 2010 5:10 PM >To: hoene@uni-tuebingen.de >Cc: codec@ietf.org >Subject: [codec] #28: Layered bit-stream > >#28: Layered bit-stream >------------------------------------+---------------------------------- - >---- > Reporter: hoene@... | Owner: > Type: defect | Status: new > Priority: minor | Milestone: >Component: requirements | Version: > Severity: Active WG Document | Keywords: >------------------------------------+---------------------------------- - >---- > Shall layered coding be supported? > Who needs it? > Can we drop this requirement? > >-- >Ticket URL: <http://trac.tools.ietf.org/wg/codec/trac/ticket/28> >codec <http://tools.ietf.org/codec/> > >_______________________________________________ >codec mailing list >codec@ietf.org >https://www.ietf.org/mailman/listinfo/codec
- [codec] #28: Layered bit-stream codec issue tracker
- Re: [codec] #28: Layered bit-stream Christian Hoene
- Re: [codec] #28: Layered bit-stream Christian Hoene
- Re: [codec] #28: Layered bit-stream stephen botzko
- Re: [codec] #28: Layered bit-stream Christian Hoene
- Re: [codec] #28: Layered bit-stream Dmitry Yudin
- Re: [codec] #28: Layered bit-stream Dmitry Yudin
- Re: [codec] #28: Layered bit-stream Dmitry Yudin
- Re: [codec] #28: Layered bit-stream codec issue tracker
- Re: [codec] #28: Layered bit-stream codec issue tracker
- Re: [codec] requirements #28 (closed): Layered bi… codec issue tracker