[vorbis-dev] replaygain support

[John Morton]

On Thursday 27 November 2003 06:56, Josh Coalson wrote:
>  what would make it easier would be a separate library for
>  replaygain with a nice, stable API so multiple projects could
>  use it without too much trouble.  there is the beginnings of
>  such a thing in the FLAC sources; if someone wants to take
>  that and run with it I'd be happy to use it.

I agree. Replaygain generally boils down to float and signed int cases for 
application at the plugin end and the initial calculation. 

vgplay is backend code for vorbis plugins, rather like vcedit, that does 
replaygain (source from tags or where ever you like), preamp gain, hard 
limiting and conditional hard limiiting, and has the iced out blingity bling 
feature of being able to smoothly transition between gain settings while the 
song is playing. It could be kicked into being a general floating point gain 
function with a vorbisfile like interface without too much trouble. 

FLAC has an implimentation of the analyser, which looks pretty much like the 
vorbisgain analyser internals, as far as I can tell, and a gain function 
designed for unsigned int which includes a basic hard limiter, as well as 
dithering.

I don't think it would be too hard to end up with a library containing a pair 
of gain functions for signed int and float, and an analyser that can cope 
with 8/16/24/32/64 bit signed int and float, mono or stereo at a variety of 
sample rates. A bit more work to handle other channel combinations, as 
someone needs to look at the analyser math for each case, but not out of the 
question. 

John

--- >8 ----
List archives:  http://www.xiph.org/archives/
Ogg project homepage: http://www.xiph.org/ogg/
To unsubscribe from this list, send a message to 'vorbis-dev-request at xiph.org'
containing only the word 'unsubscribe' in the body.  No subject is needed.
Unsubscribe messages sent to the list will be ignored/filtered.