Well, it was easy enough to compare ATRAC3 at 66, 105, and 132kbps to a WAV
file. It was much harder to compare plain ATRAC since I couldn't get it
directly onto my PC (yet). There appears to be too much jitter when playing
back from my JB920 thru TOSlink into my Canopus MD-Port and into the PC over
USB.
For the ATRAC3 comparisons, I used a WAV file ripped directly off CD.
(Altan's Harvest Storm, track 10, The Rosses Highlands). For the ATRAC file,
I digitally copied the CD track from my DVP-C600D to the JB920 (using
TOSlink). I then played the MD track over TOSlink into the computer.
Unfortunately, I was completely unable to synchronize the MD copy with my
original WAV file. I could analyze the samples and sync-up at a given point,
but within about 10000 samples it was out of sync again. Figuring that there
may be jitter introduced when playing the CD to MD, I
re-recorded the original WAV file as well: I recorded the music track from
CD to MD, and also recorded the digital output of the JB920 on the PC at the
same time. (I.e., digitally recorded the monitored audio.) I figured this
would give me a WAV file with the exact same CD jitter characteristics as
what the JB920 recorded. I then played back this new MD track, recording it
onto the PC, and compared this track with the monitored track. Again, I
could sync-up at one point, but the two tracks would be out of sync within
about 4000 samples. So, it's been pretty much impossible for me to do a
direct bit-for-bit comparison of the ATRAC audio with the original WAV data.
I wonder if any of the available re-clocking jitter-reduction boxes would
help here...
-- Howard Chu
Chief Architect, Symas Corp. Director, Highland Sun
http://www.symas.com http://highlandsun.com/hyc
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