Re: [SoX-users] audio length is neither known nor given ?

[Thor A. <ta...@to...>]

On Thu, Sep 22, 2011 at 09:20:15AM +1000, pj...@pj... wrote:
> I wrote:
> >   box8 (debian) 201109> play 16_1148_xv.wav fade 0 0 1.0
> >   ...
> >   play FAIL fade: cannot fade out: audio length is neither known nor given
> >  http://www.pjb.com.au/tmp/16_1148_xv.wav
> 
> Chris Bagwell wrote:
> > Your probably using a length changing effect without knowing it
> > during your playback.  Use the -V option to see whats being added.
> > In this case, probably your sound card requires resampling the
> > audio to a certain rate.  Resampling is a length changing affect.
> 
> So I tried writing to a file:
> 
>   box8 (debian) 201109> sox 16_1148_xv.wav x.wav fade 0 0 1.0
>   sox FAIL fade: cannot fade out: audio length is neither known nor given
>   box8 (debian) 201109> sox -V 16_1148_xv.wav x.wav fade 0 0 1.0
>   sox: SoX v14.3.1
>   sox INFO formats: detected file format type `wav'
> 
>   Input File     : '16_1148_xv.wav'
>   Channels       : 2
>   Sample Rate    : 44100
>   Precision      : 16-bit
>   Duration       : 00:01:23.75 = 3693532 samples = 6281.52 CDDA sectors
>   File Size      : 14.8M
>   Bit Rate       : 1.41M
>   Sample Encoding: 16-bit Signed Integer PCM
>   Endian Type    : little
>   Reverse Nibbles: no
>   Reverse Bits   : no
> 
> 
>   Output File    : 'x.wav'
>   Channels       : 2
>   Sample Rate    : 44100
>   Precision      : 16-bit
>   Sample Encoding: 16-bit Signed Integer PCM
>   Endian Type    : little
>   Reverse Nibbles: no
>   Reverse Bits   : no
>   Comment        : 'Processed by SoX'
> 
>   sox FAIL fade: cannot fade out: audio length is neither known nor given

I also see this issue, upon exploring it further I found that this seems
to be a general problem, filelength does not seem to be propagated to
the effects chain, at least not through the effp->in_signal struct. I
traced it back to line 166 of effects.c:

*in = effp->out_signal;

Removing that line fixes the issue. What other ramifications this has is
not clear to me, but I see no obvious ill effects ... but I may be
blind.

-- 
best regards
Thor Andreassen