[mythtv] Time Stretch with PVR-350 (Possible solution to adjust audio pitch)

Nick Rosier nick.rosier at gmail.com
Sat Apr 30 15:02:11 UTC 2005

On 4/30/05, Allan Stirling <Dibblahmythml0015 at pendor.org> wrote:
> Frank Riley wrote:
> >>The code's already in Myth to do this - It's just a matter of "plugging
> >>it in" for this special case, if I understand the issue.
> > Could you please explain? I was approaching it such that I would capture the
> > sound from line in, then send the captured sound through the existing sound
> > code for playback. I don't currently see any code to do the line in capture.
> > Am I missing something?
> I was specifically talking about the time stretch pitch adjustment that
> the poster I commented to was thinking needed reimplemented.


AFAIK it is there if you're not using a PVR-350 to do the decoding,
i.e. software MPEG2 decompression; the 350 doesn't adjust pitch (well
I've heared it maybe can do it for x1.5 but then the driver would have
to implement it).
There's a checkbox in the setup where you can specify that you are
using the 350 audio out (so the volume controls etc don't work). I'm
suggesting adding an option where you tell MythTV that the 350-audio
is redirected to line-in of your soundcard; line-in is real-time
pitch-adjusted and played back through your soundcard to your stereo.


you might be able to re-use the soundtouch libraries currently used by
Myth to do the pitch-adjust if you are using software MPEG2
decompression. I was trying with sox as I know how to work that one.


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