Re: [codec] #28: Layered bit-stream

["Christian Hoene" <[e-mail]>]

Hi Dimitry,

>Hi Christian,
>
>From application point of view, the layered stream structure allows
>server manipulate channel bandwidth individually for each user with zero
>performance overhead. 

I understand. Because you as an application programmer want to have an easy life, the codec designer shall develop a more
complicated codec? In addition, everybody should suffer from a higher bit rate? No, that is not fair.

> Obviously, conferencing is the most important use-case.

No, end-to-end connections are more frequent than conference calls.

>
>> 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?

I mean that the layered coding is only used within one computer. It is not important in-between computers. And, it is only a
performance optimization that make the conference gateway faster.

Sincerely,

 Christian


>
>> 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:[e-mail]]
>Sent: Wednesday, May 05, 2010 11:02 PM
>To: Vladimir Sviridenko; [e-mail]
>Cc: Slava Borilin; Dmitry Yudin; [e-mail]
>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: [e-mail] [mailto:[e-mail]] On Behalf
>>Of codec issue tracker
>>Sent: Sunday, May 02, 2010 5:10 PM
>>To: [e-mail]
>>Cc: [e-mail]
>>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/>
>>
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