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2-41] What's Audio Master Quality (AMQ) recording?




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This article is from the CD-Recordable FAQ, by Andy McFadden (fadden@fadden.com) with numerous contributions by others.

2-41] What's Audio Master Quality (AMQ) recording?

(2002/05/08)

Yamaha developed Audio Master Quality Recording to compensate for higher
"jitter" in recorded CDs. This is not the kind of jitter addressed by
"jitter correction" in CD rippers (2-15). This is the "jitter" that people
selling fancy stereo equipment talk about.

Jitter is time-base error. It's not a corruption of the digital '1's and
'0's, it's a distortion of the timing in which the '1's and '0's arrive at
their destination. This doesn't affect extraction of audio, so you don't
need to worry about this kind of jitter when reading a CD or ripping to MP3.
You do need to worry about it when listening to a CD.

The digital signal is read from a CD via an analog process: bouncing a
laser off of "pits" and "lands" on a CD. Various factors can prevent
the signals from arriving at the right place at exactly the right time.
High-end CD players can correct these anomalies, but many don't.

AMQ extends the length of the pits and lands on the CD in an attempt to
produce a more stable signal. This reduces the recordable length of the
CD -- a 74-minute disc only holds 63 -- but produces noticeably improved
audio (says Yamaha). The process works because CD players automatically
adjust the rotation speed.

Yamaha's explanation: http://www.yamaha.ca/computer/cp_AudioMQR.asp

See also section (4-18-2).


 

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