[icecast] question on downsampling

Akos Maroy
Fri, 06 Aug 2004 14:22:38 -0000

Hi,

Maybe a bit off topic for this list, bt anyway.

I have received several feature requests for DarkIce to support
downsampling of the audio input before passing it to lame or ogg vorbis.
For example the audio read from the soundcard would be 44.1kHz, and lame
would get it at 22.05kHz.

I figure two ways of doing this:

1. For lame, one can specify the input and the desired mp3 sampling
rate, and lame will downsample the data as needed. I didn't find such
possibility for vorbis. For lame, this increases the processing need
quite a lot (almost double as I measure).

2. Downsample in DarkIce, by simple means. For example, from 44.1kHz ->
22.05kHz, simply send one sample for every two imput samples, taking
their average value. This shouldn't result in large computing overhead,
and I could also do it for vorbis.

As there are people on the list more clever than me, I'd like to know
what downsides are there for point 2?

Thanks,

Akos