ssave@caen.engin.umich.edu (Shailendra Anant Save) (12/03/90)
Would some knowledgeable person please answer some questions
that I have:
0> What is the format of storage of digital audio on CDs? What is
the width ie. number of bits? Per channel?
1> What is the frequency of sampling (reading?) of the disk?
1a> What does 4X and 8X sampling mean?
2> What is the total amount of memory on a disk?
3> What type of digital output do you get when you probe the
digital o/p pin on the chip or from the digital output of the
player when available? Does it have start and stop bits? Must
be serial.
Please get as technical as you want.
--Shailendra
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(For those who don't know, a weasel is a wolverine)esmith@goofy.apple.com (Eric Smith) (12/03/90)
In article <1990Dec2.224254.28356@engin.umich.edu> ssave@caen.engin.umich.edu (Shailendra Anant Save) writes: > 0> What is the format of storage of digital audio on CDs? What is > the width ie. number of bits? Per channel? 16 bits per channel 1> What is the frequency of sampling (reading?) of the disk? 44.1 kHz 1a> What does 4X and 8X sampling mean? This is just a function of the player, not the disk. It refers to the use of a digital filter to do sample rate conversion to 176.4 or 352.8 kHz prior to D/A conversion. This allows the use of a simpler reconstruction filter (lowpass analog filter), which is used to remove the frequency aliases above half the sample rate. The simpler filter doesn't have as steep a slope, and doesn't introduce as much phase distortion into the signal. 2> What is the total amount of memory on a disk? It depends on how you look at it. A lot of the disk is taken up by error correction codes. There is also subcode data that is used for the time display, table of contents, etc. CD-ROMs, which add additional error correction beyond that of CD-Audio, are commonly spec'd at 550-650 Mbytes. 3> What type of digital output do you get when you probe the digital o/p pin on the chip or from the digital output of the player when available? Does it have start and stop bits? Must be serial. Depends on the chip set used in the player. Generally synchronous serial. There is no standard for signals inside the player. There are standards for digital audio interconnects. Get the book _The_Art_of_Digital_Audio_. -- Eric L. Smith Opinions expressed herein do not necessarily reflect those esmith@apple.com of my employer, friends, family, computer, or even me! :-)