[vorbis-dev]Newbie question

[Beni Cherniavsky]

On 2003-01-19, Segher Boessenkool wrote:

> Rob D wrote:
> >
> > The problem isnt with finding a place to store the settings. They are stored
> > in a separate database, works fine, and is per album, and not per song
> > anyway.
> >
> > You are right in that it wouldnt make sense to store volume/EQ settings in
> > the file, because as you mentioned, the sound system it is played back on
> > has a huge affect on the sound relationship.
> >
> > The problem is not knowing how to tell the decoder I want 85% volume as
> > opposed to the normal volume when it is creating the PCM samples.
>
> The least-processor-intensive way of doing this would be to either scale
> the floor-decibels table, or the mdct windows.You'll have to hack this
> into the libs yourself, though.
>
I recall a disscussion on permanently changing the volume of a vorbis
stream (see http://www.xiph.org/archives/vorbis-dev/200105/0139.html and
forward).  From it I gather that for long enough streams, presclaing
something in the codebooks can be even more effecient.  This is probably
hairy to do properly and it doesn't allow changing the volume during
playing.  There was also mention of a per-packet master volume setting;
adjasting it in the packet prior to the decoding is probably best (and it
could even be done between libogg and libvorbis without touching their
internals; I don't know if that will be easier).


-- 
Beni Cherniavsky <cben at tx.technion.ac.il>

There is an Excel spreadsheet here.  Do you want to open it? y
There was a grid bug in the spreadsheet.  The grid bug bites.

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