[Ffmpeg-devel] alsa input / output

Rich Felker dalias
Wed Mar 21 03:42:38 CET 2007


On Wed, Mar 21, 2007 at 12:52:47AM +0000, M?ns Rullg?rd wrote:
> Assuming the input is not undersampled, is there not exactly one
> mathematically correct resampling?  It's been a while since I studied
> signal processing, so I may have forgotten something.

Yes. Unfortunately it's O(?)... :)
The mathematical model (signals that are infinite in time) sadly does
not actually correspond to reality, and no one really knows what the
correct model (as opposed to this ideal model) should be. Fortunately
the error is sufficiently small that you can pretend the ideal model
is real if you use moderately long windows.

> BTW, ALSA 1.0.14-rc3 can use libavcodec for resampling.

Great, Nik's patches were accepted I guess! However, I bet this means
all sorts of nightmares for symbol namespace clash..... Or do I
misunderstand how ALSA libs work?

Rich




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