A few more notes:

1.  If your DAW does not have an "audio file compare" 
    function, you can also generate an MD5 checksum
    for the original file and the "reverse 2x" file.
    The MD5 checksums should be identical.  I just 
    ran this test with my Cube-Tec Audiocube software,
    and the checksums were indeed identical.

2.  In case it wasn't clear, it should not matter 
    whether you are reversing a stereo or mono file.
    I ran the tests described here on an interleaved
    stereo BWF WAVE file.

Eric Jacobs

The Audio Archive, Inc.
tel: 408.221.2128
fax: 408.549.9867
mailto:[log in to unmask]
http://www.TheAudioArchive.com
Disc and Tape Audio Transfer Services and Preservation Consulting

-----Original Message-----
From: Eric Jacobs [mailto:[log in to unmask]]
Sent: Thursday, October 08, 2009 8:47 AM
To: Association for Recorded Sound Discussion List
Subject: RE: [ARSCLIST] Reverse engineering



On Thursday, October 08, 2009 7:36 AM, Steven Smolian wrote:

> Is there a loss of data accuracy when reversing a sound 
> file?  In mono?  In stere?

Mathematically, no loss.

Implementation, possible loss.

Reversing the audio is relatively straight-forward, and 
is usually implemented correctly in most DAWs.

If your DAW has an "audio file compare" function, you 
can run a quick experiment to validate that the reversal
process is accurate:

   - select a file
   - make a copy of the file
   - reverse the copy and then reverse it again (reverse 2x)
   - save the "reverse 2x" copy
   - compare the original file and the "reverse 2x" copy

The two files should be absolutely identical.

I just ran this test on my Cube-Tec Audiocube (64-bit 
version of Wavelab 6.10) with a short 7-minute audio file, 
and the entire process above took less than 4 minutes.

The two files were indeed absolutely identical.

Eric Jacobs

The Audio Archive, Inc.
tel: 408.221.2128
fax: 408.549.9867
mailto:[log in to unmask]
http://www.TheAudioArchive.com
Disc and Tape Audio Transfer Services and Preservation Consulting