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Author Topic: The Pace of Digital Audio?  (Read 1794 times)

mark4man

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The Pace of Digital Audio?
« on: June 12, 2004, 07:01:00 pm »

Hey...

No...this isn't one of those "state-of-the-art" type questions (& please don't regard it as a dumb one, either)...but somewhere in my studies, I sort of glossed over this area, taking everything for granted as, let's say...automatic.

The question is:

What determines the pace of PCM digital audio (in terms of both recording & playback)?

Is it the synchronization & address information included with the Data Coding applied during the record modulation (PCM) process (in the ADC)?  (& then reversed in the DAC)?

[Now, as an example of how I came to this question...

...in my native DAW (SONAR XL), I set the tempo of a project; & connect a synth module to the puter.  The DAW plays the instrumentation from the module in accordance with the notation within a MIDI track...at that set tempo.

I now record the MIDI music as 16/44.1 digital audio; & the now time needle rolls at a certain pace.

(BTW - I understand that the project tempo is a reference value related to MIDI sequencing...that the needle always rolls at the same pace...& that the only aspect that changes is the graphic representation of how far apart the measures are positioned...this I know.)]

But, as just mentioned, the needle always rolls at the same pace.

I bounce my multiple audio tracks to a stereo .wav file, open & play the .wav file in my audio editor (WaveLab); & the needle rolls at the same pace.

I burn the .wav file to CD-R, play the composition on my bookshelf stereo system; & it plays at the same pace.

If this is all simply determined by a master clock in each device (from the sound card to the CD player)...do the clocks all run in real time (i.e., 1 sec. = 1 sec., 1 min. = 1 min., etc.)...& the pace of the clock being determined by the sample rate of the PCM audio in ratio to the sync info embedded in the file?

Is that it?

If not...what is it ('cause all of a sudden, this is driving me nuts, for some reason.)

Thanks very much,

mark4man
Mark Forman
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