Vorbis dev - Nov 2005 - wavelet transform

Hello,

I am thinking about plugging in Discrete Wavelet Transform as
described in Vorbis I spec:

1.1.2. Classification
Vorbis I is a forward-adaptive monolithic transform CODEC based on the
Modified Discrete Cosine Transform. The codec is structured to allow
addition of a hybrid wavelet filterbank in Vorbis II to offer better
transient response and reproduction using a transform better suited to
localized time events.

Could anybody tell me if it's good or bad idea?


--
Dominik Zalewski

Adam Mickiewicz University, Department of Mathematics and Computer Science
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On Tue, Nov 29, 2005 at 10:54:46AM +0100, Dominik Zalewski
wrote:
> Hello,
> 
> I am thinking about plugging in Discrete Wavelet Transform as
> described in Vorbis I spec:
> 
> 1.1.2. Classification
> Vorbis I is a forward-adaptive monolithic transform CODEC based on the
> Modified Discrete Cosine Transform. The codec is structured to allow
> addition of a hybrid wavelet filterbank in Vorbis II to offer better
> transient response and reproduction using a transform better suited to
> localized time events.
> 
> Could anybody tell me if it's good or bad idea?
As a direct replacement for the MDCT?  Very likely a bad idea. For
one, encoder doesn't know how to analyse the output of a DWT, and even
if it did, it will probably give mych poorer energy compaction than
the MDCT.

Wavelets have their use, but not really as a substitute for the MDCT.

Monty