[mythtv] Question/request: mythtranscode resampled output

Geoffrey Hausheer ou401cru02 at sneakemail.com
Sat Oct 18 15:08:04 EDT 2003


On Sat, 18 Oct 2003 08:21:01 -0400, "Joseph A. Caputo
jcaputo1-at-comcast.net |mythtv/1.0-Allow|" <s9v7hefgnx0t at sneakemail.com>
said:
> Hi,
> 
> I've been poking around in the code trying to figure out how to do this, 
> but I'm just not familiar with all of the Nuppel/Lame/libavcodec stuff, 
> and I thought maybe someone more familiar might say 'oh, yeah, that's 
> easy...'
> 
> What I'd like to do is add the capability for mythtranscode to resample 
> the audio (I can add the support code; i.e., command line switches, etc; 
> it's just the actual resampling that I'm uncertain of).  I'm primarily 
> interested in having the output resampled when using 'raw' output from 
> mythtranscode, but I suppose some might find it useful (??) in a 
> transcoding profile as well.  Anyway, cursory examination makes me think 
> that currently the AudioOutput/AudioBuffer classes kind of 'no-op' the 
> output sample rate stuff and just assume it's the same as the input 
> sample rate.  Is this correct?  I'm kind of lost as to where to hook 
> stuff up.  If someone familiar with this code is willing to give it a 
> shot, I'll happily 'trade' patch efforts for some UI-type work.
> 
I'm not sure of a good way to do that.  Once we have an algorithm that
resamples the audio, it should be added to the AudioReencodeBuffer class.
 But I think such resampling needs to be done in the frequency domain,
and I don't remember any of my Laplace transform stuff.  Maybe it can be
done easily in the time domain (it's been 10 years since I've done audio
processing, so i really don't know).  If you like, I'll take a look at
it.  I wouldn't expect it to take much coding to implement.  I guess the
real question is why you need it?  Most tools that can read the fifo
output data should be capable of resampling the data.

.Geoff


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