[LAU] stereo channel differeces

[Robin Gareus]

On 01/01/2013 07:07 PM, Brent Busby wrote:
> First off, Happy New Year to all!  :)
> 
> Can anyone recommend a quick way of seeing the differences highlighted
> visually between two channels in a stereo sample...sort of like a
> graphical 'diff' for waveforms?
> 
> I think I may have some Akai MPC2000 samples that somehow were saved by
> the Akai as mono samples even though they actually contain two channels
> and are really stereo:
> 
> Using 'sndfile-info' on them reports them as mono, but it's just looking
> at the 22nd byte in the file, which should contain 0x00 or 0x01 to say
> if it is mono or stereo.  The file contains 0x00 in that location, so
> sndfile-info believes that it's mono because the file header says so.
> 
> However, if I flip the bit in a hex editor and resave the file, now I
> can load the file in a sample editor and it seems to have two channels
> which play at double speed.  I'm still not positive I'm hearing stereo
> (if I am, it's very subtle), but I'm definitely seeing two channels
> visually, and I know this sample was sampled on the Akai in stereo.
> 
> Any way to do a graphical comparison that will highlight even small
> channel waveform differences?
> 

Invert the phase of one channels (volume *=-1) and downmix to mono. If
both channels are identical it'll result in a flat zero line.

I'd use rezound for that, but pretty much any soundfile editor should do.

HTH,
robin