Forums

OT Clock Speeds

Started by Unknown September 27, 2003
Maybe someone here is knowledgable re clock usage in a Windose
environment...

1- If I capture my (high-end) sound card ADC output to disk, is it paced by
the card's clock or the computer's clock?

In other words, the 44100 samples/second is who's "second"?

2- If I play a wav file is it paced by the sound card's clock or the
computer's clock?

3- If I play a CDDA disk (with no sound card involvement), is the
front-panel analog output paced by the computer's clock or by the drive's
own clock?

4- If I use a program to play the same CDDA internally (signal comes
through the internal 40-pin ribbon cable), who's clock is being used?

An educated guess is welcome but please warn me.

TIA
Les
In comp.dsp, vista55remoove@nyc.rr.com wrote:

> >Maybe someone here is knowledgable re clock usage in a Windose >environment... > >1- If I capture my (high-end) sound card ADC output to disk, is it paced by >the card's clock or the computer's clock?
This is the soundcard's clock, based on a quartz crystal on the soundcard. It's possible to use two soundcards in one machine and (using a suitable application - a DAW/multitrack recording software) and either record or play back through both of them at once. The tracks may be off as much as 1/10th second between soundcards after several minutes. You should be able to find where this was tried and documented on alt.music.4-track through groups.google.com. What model do you have that is "high-end"? M-Audio makes several models of cards that are syncable, and may work differently.
>In other words, the 44100 samples/second is who's "second"? > >2- If I play a wav file is it paced by the sound card's clock or the >computer's clock?
Sound card, again.
>3- If I play a CDDA disk (with no sound card involvement), is the >front-panel analog output paced by the computer's clock or by the drive's >own clock?
Definitely the drive's clock. You can power the drive with 5 volts (it may need 12 volts also/instead, I don't know offhand), put in an audio disc, and it will play it all the way through all by itself. Plug headphones into the 1/8" mini stereo jack to listen. Thus a CDROM drive doubles as a stand-alone CD player. The Windows "cd player controller" app reads (I presume using the IDE interface) the drive to see what track and time it's playing, and the drive responds to (I presume IDE) commands to change tracks, start and stop and stuff.
>4- If I use a program to play the same CDDA internally (signal comes >through the internal 40-pin ribbon cable), who's clock is being used?
If you mean, for example, you're playing it with Windows Media Player and "digital playback" is checked, then the data is "ripped" off the disc in real time (read as if the drive were reading a file from a data CDROM), read through the IDE, goes through the motherboard and to the soundcard, and so the rate is then determined by the soundcard's crystal.
>An educated guess is welcome but please warn me.
I'm 98 percent certain on the soundcards (I don't know how M-Audio syncs different cards without a physical connection between them outside of the bus), but 100 percent certain on the CDROM drive as a stand-alone player. Of course the next poster will have incontrovertible evidence to the contrary...
>TIA >Les
----- http://mindspring.com/~benbradley
Hi Ben--

I know your name from the RAP group and I couldn't have asked for a better
responder -- You're knowledgable in electronics and audio, accurate, and
cynical. Thank you for the response. It 'sounds' correct in all respects.

It's a relief to hear the computer's clock is never used to pace the
samples, since these clocks are notoriously inaccurate.

I suppose the M-Audio driver 'syncs' the 2 cards with some periodic
adjustment. Just a guess of course.

I use a Gina20 and I love it.

See you there.

Les
========================

ben_nospam_bradley@mindspring.com (Ben Bradley) wrote:

>In comp.dsp, vista55remoove@nyc.rr.com wrote: > >> >>Maybe someone here is knowledgable re clock usage in a Windose >>environment... >> >>1- If I capture my (high-end) sound card ADC output to disk, is it paced by >>the card's clock or the computer's clock? > > This is the soundcard's clock, based on a quartz crystal on the >soundcard. > It's possible to use two soundcards in one machine and (using a >suitable application - a DAW/multitrack recording software) and either >record or play back through both of them at once. The tracks may be >off as much as 1/10th second between soundcards after several minutes. >You should be able to find where this was tried and documented on >alt.music.4-track through groups.google.com. > What model do you have that is "high-end"? > M-Audio makes several models of cards that are syncable, and may >work differently. > >>In other words, the 44100 samples/second is who's "second"? >> >>2- If I play a wav file is it paced by the sound card's clock or the >>computer's clock? > > Sound card, again. > >>3- If I play a CDDA disk (with no sound card involvement), is the >>front-panel analog output paced by the computer's clock or by the drive's >>own clock? > > Definitely the drive's clock. You can power the drive with 5 volts >(it may need 12 volts also/instead, I don't know offhand), put in an >audio disc, and it will play it all the way through all by itself. >Plug headphones into the 1/8" mini stereo jack to listen. Thus a CDROM >drive doubles as a stand-alone CD player. The Windows "cd player >controller" app reads (I presume using the IDE interface) the drive to >see what track and time it's playing, and the drive responds to (I >presume IDE) commands to change tracks, start and stop and stuff. > >>4- If I use a program to play the same CDDA internally (signal comes >>through the internal 40-pin ribbon cable), who's clock is being used? > > If you mean, for example, you're playing it with Windows Media >Player and "digital playback" is checked, then the data is "ripped" >off the disc in real time (read as if the drive were reading a file >from a data CDROM), read through the IDE, goes through the motherboard >and to the soundcard, and so the rate is then determined by the >soundcard's crystal. > >>An educated guess is welcome but please warn me. > > I'm 98 percent certain on the soundcards (I don't know how M-Audio >syncs different cards without a physical connection between them >outside of the bus), but 100 percent certain on the CDROM drive as a >stand-alone player. > Of course the next poster will have incontrovertible evidence to >the contrary... > >>TIA >>Les > >----- >http://mindspring.com/~benbradley