[mythtv] [mythtv-commits] Ticket #1104: multi channel audio support
danielk at cuymedia.net
Fri Feb 1 22:18:05 UTC 2008
On Sat, 2008-02-02 at 09:10 +1100, Mark Spieth wrote:
> > Mark, how much work would it be to use ffmpeg's fourier transforms if
> > fftw3 isn't available?
> > Also, if we do use fftw3, we're going to need to check for it in
> > ./configure and not use it if it isn't installed..
> I havent analysed this yet. Note that mythmusic uses fftw3 already.
> Hoever on a quick look at fft.c, fft-test.c it wouldnt be too hard.
> However, lavc fft doesnt have a real-complex mode which only uses 1/2 the
> result (due to odd symmetry inherent in this mode of fft) so I suspect it
> will be slower. If this is important its doable within a few hours.
> Things that need to change are the init/finalize, and filtering needs to be
> modified to use all 8k freq domain samples instead of 4k freq domain samples
> due to the symmetry not being redundant. scaling should be the same.
I think it's important because this still adds another lib requirement.
For MythMusic it isn't a required lib. We should still use fftw3 when
it's available. It really is the fastest free FFT library out there.
> Still working on bug fixes. Ive figured out why swapping from 2 to 6 and
> back doesnt work. still working on a fix but lavc has a couple of changes to
> support it. hopefully an update this weekend for this.
Cool, finding the cause is usually more than half the work.
Did you figure out the problem with DVB radio too?
More information about the mythtv-dev