[matroska-general] Re: =[SPAM?]= Re: Dynamic Range Management

Frank Klemm pfk at fuchs.offl.uni-jena.de
Sun May 25 20:39:56 CEST 2003


On Sun, May 25, 2003 at 04:31:48PM +0200, Steve Lhomme wrote:
> >
> > Question
> > ~~~~~~~~
> > 
> > What do you think about this idea ?
> > Should this be part of Matroska or part of SV8 ?
> 
> It depends if it's a codec specific thing, or it can be applied to any 
> codec. In the latter case, I suggest to put it in Matroska. We already 
> have ReplayGain informations (album and track). And we can add this to 
> any audio block "properties" (saved in the BlockGroup, even better in 
> the TimeSlice). 
>
The Dynamic Changes are not specific to an audio block.
A new setting can be choosen after 64, 256, 1024 or 4096 samples and this
new value is applied smoothly between the two props.


> The problem is that it would be more convenient for the 
> decoder to have the value for each "frame" and not just when it changes. 
> Otherwise when you cut or seek in the file, you will lose that information.
>
Known.

 
> BTW, I'm thinking about when to apply it on decoding. It should be after 
> decoding to PCM, 
>
Dolby Digital applies it to the MDCT coefficients. Side effect is that so
the DRC is applied smoothly.

> so either in the Codec (ie this is codec specific, not 
> supported by all possible codec in matroska) or hacking the output of 
> the codec (dirty hack in DirectShow, it may be easier in MPlayer). So a 
> codec specific system would be easier on the matroska side ;) 
>
Known.


> But that's a feature that could be worth adding. To make all codec equal on this 
> side :) 
>
Known. Guess why I'm asking ...


> And let the codec really deal with coding data. But I'm not sure 
> it will be the case on encoding, as only the codec can know how to 
> manipulate data to make compression better.
>
The task is not to compress(1) the signal to make it easier to compress(2),
but to allow a playback in a noisy enviroment or in the late evening.
Or to apply a fade in and fade out after encoding of the signal.

> 
>  > Generic forms:
>  >
>  >   - up to 32 profiles
>  >   - volume can be changed static and dynamic
>  >   - can be used like DRC and Compression
>  >   - can be used for album replaygain
>  >   - can be used for title replaygain (with additional transition
>  >     between titles, to avoid clicks)
> 
> Good idea. Even though it will need support in the authoring app (not 
> muxing app).
> 

SV8:
- decoder do it automatically
- you have a function 
  - to get number of channels
  - to select the channel
- editing/manupulation tools are SV8 related


MATROSKA:
- range management is done by the matroska framework
- usable for all audio file formats
- editing/manupulation tools are MATROSKA related
- dynamic range stream can have names ...
- more fexible I think

-- 
Frank Klemm


http://www.matroska.org




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