Re: [SoX-users] SoX Stats: add peak position? (N Arora)

[nitin a. <nit...@gm...>]

Hello,

"The min and max values and postions as reported by soundforge seem to be
the same in the mono file and in the right channel of the stereo file.
Where do monotest.wav and stereotest.wav come from? Also, a 3s file and
a 53s file are probably small enough, can you please put them somewhere
for download?"

They're just files I made up with Sony Sound Forge and a snippet of
something lying around at work.
I've uploaded a zip file here:
http://opensourcelibrarian.org/statTest/sony_vs_sox.zip

It has 4 WAV files (mono, 2 stereo, and a quad-channel) and a text file
comparing the results.
The stereo files are slightly different than the ones I posted about last
week. I shortened them to make the zip files smaller but the text file has
up-to-date comparisons between the two applications' statistical reports.

It looks with stereo files, the ratio is 2:1 in terms of SoX:Sound Forge
regarding the sample at which the max or min is reported to be.
That is to say if SoX is saying the max value occurs at sample 20, then
Sound Forge is saying it occurs at 10 and also specifies which channel it's
coming from.

With a quad-channel file, SoX was reporting a sample location of 4x what
Sony was reporting.

"Could the "*2" difference be caused simply by disagreeing on what
"sample" means? In soundforge, is "sample" the sampled data for
both left and right channel, or just one of them? That could
be an explanation, because the values themselves are the same:
51.904 max and -53.473 min.

(Which does not explain it for the mono case, however.)
"

Are you saying that for SoX it's adding up ALL the samples up to the point
at which the peak occurs and reporting that sample as the location of the
peak regardless of how many channels there are?
The Sound Forge definitely appears to be considering each channel
individually. i.e. the sample start position for each channel is "0" for
Sound Forge whereas for SoX the starting point is sample "0" only for the
first channel.
I still don't understand what's going on with the discrepancy regarding the
mono file though. The max/min percentage values are the same for both apps,
but in terms of position they only agree on the location of the max.

"Why does this report the min and max values in dB
(so that I cannot directly compare it to the above)?"

Sorry that was my bad in not changind the setting. More me getting
cross-eyed. :-)
The text file I mentioned doesn't have this mistake.