[mythtv] Re: [mythtv-commits] mythtv commits libsamplerate andlibsoundtouch integration

Mark Spieth mark at dclabs.com.au
Tue Oct 26 13:17:16 UTC 2004

libsamplerate does not appear to do time stretch, only samplerate

from the web page of soundtouch.
a.. Tempo (time-stretch): Changes the sound to play at faster or slower
speed than original, without affecting the sound pitch.

The sample rate stays the same. the sound is compressed/expanded without
affecting the understandability etc.
thus you can fast forward with audio on at various rates to x2.
I have currently got soundtouch installed in libmyth/soundtouch
Is that acceptable? I suppose it doesnt matter in the long run. just when I
submit the patch.
Ill reposition if an alternate spot is favored.
yes I was going to put it in that class with hooks into the derived classes.


----- Original Message ----- 
From: "Ed Wildgoose" <lists at wildgooses.com>
To: "Development of mythtv" <mythtv-dev at mythtv.org>
Sent: Tuesday, October 26, 2004 10:27 PM
Subject: Re: [mythtv] Re: [mythtv-commits] mythtv commits libsamplerate
andlibsoundtouch integration

> Mark Spieth wrote:
> >I would like to integrate libsoundtouch into myth.
> >what is the preferred way/location? looks like it may fit in with
> >libsamplerate in concept.
> >what libsoundtouch can do is to time stretch audio whilst keeping the
> >rate constant.
> >i.e. a 1.05 factor faster will reduce the number of samples by 5% keep
> >quality audio the same.
> >I will hold off until this is stabilized. oss and alsa audio modules is
> >where I was going to put the processing.
> >it introduces about 100ms latency which is not too bad.
> >
> >
> You can do all of this and more using libsamplerate.  It takes arbitrary
> resampling ratios.  It will do it with zero latency as well...
> Look to add such code into the AudioOutputBase class and then all the
> subclasses will inherit from it.
> There is still a little bit of refactoring to come to the audio classes,
> but that main checkin will probably have all the main stuff.  It should
> make this kind of thing a heap load easier to integrate.
> Let me know if you have some problems using it
> Ed W
> _______________________________________________
> mythtv-dev mailing list
> mythtv-dev at mythtv.org
> http://mythtv.org/cgi-bin/mailman/listinfo/mythtv-dev

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