Re: [SoX-users] sox adding noize when file smashing

[Chris B. <ch...@cn...>]

On Wed, Mar 05, 2008 at 01:15:54PM -0700, Robert Ferney wrote:
> Hi Yall,
> I'm using sox to convert and downgrade audio files to 8bit 8khz mono wav
> files ( Microsoft PCM and IMA ADPCM encodings ) to be used in a hardware
> device, which is only programmed to read those two formats.
> 
> Test input file is 16bit 44.1khz WAV
> 
> I'm currently using..
> > sox input.wav -s -1 -r8000 -c1 output1.wav stat
> and
> > sox input.wav -s -1 -r8000 -c1 output_.wav stat
> 
> When I listen to the files afterwards, I can hear static in the background.
> How can I eliminate this?
> When using GUI tools to do the transformation, they don't have the static I
> hear from SoX
> sox -version reports..  sox: v13.0.0
> 

I don't really use ADPCM files so can't comment much on if I've heard
noise or not.  But here are some suggestions that might help:

1) Upgrade to v14.0.1 in case a bugfix in this area was already done.
2) Try lowering the volume some to prevent clipping.

  sox -v 0.80 input.wav -s -1 -r8000 -c1 output1.wav

3) Do a search on the SoX mailing list for ADPCM and DCShift.  Rob's
mentioned in the past about how you can add a filter effect to
the command line to simulate what some GUI's are doing.  It may
clear up your noise.  A DCShift could be the cause of clipping/noise.

Chris