Can jitter be fixed in advance?

[johnthedoctor]

Sorry if it's a stupid question, I'm trying to learn.

The jitter thing does get me confused. Beginning the see the problems with digital signals but I'm wondering why my PC has to treat every wav file as if it's never seen it before. If sending the signal to the dac makes it come out wrong, ie. jitter, would it be possible to calculate the error and create a 'wrong' wav file that was jitter correct when it got to the dac?

iow, is there any way of processing wav files to get them sounding better?

[dsavitsk]

If you drop a glass on the floor, it will break into many pieces. Is there any way to drop broken glass on the floor such that it will reassemble itself?

[anatech]

Hi johnthedoctor,
What dsavitsk is saying is that jitter is a random timing error. No program will eliminate it. There may be better ways to process it but that's up to your harware and driver developers.

-Chris

[Sunsun22]

If jitter is a problem when CD plays, is it possible to copy the files to PC then play it from the hard disk?

Copying files from CD to hard disk has to start with the CD ROM that produces jitter and eventually distorted the music file. However, file copy has CRC check that the PC will compare the file between CD and hard disk, correct and re-correct until the two files are identical. When hard disk replay the file, would jitter still present?

[b-square]

Originally posted by Sunsun22
If jitter is a problem when CD plays, is it possible to copy the files to PC then play it from the hard disk?

Copying files from CD to hard disk has to start with the CD ROM that produces jitter and eventually distorted the music file. However, file copy has CRC check that the PC will compare the file between CD and hard disk, correct and re-correct until the two files are identical. When hard disk replay the file, would jitter still present?

yes, jitter will still be an issue, though likely for different reasons. you want less jitter, you use a good clock.


bb

[Mikett]

jitter is NOT part of the data but is a result of data bits not coming "on time". You can have BIT accuracy but the tiiming is off. You have to appreciate that when a data file is converted back into music, it is crucial that everything be perfectly on time because we hear things based on timing NOT based on the accuracy of the bits. Just imagine if your ears heard half a word wrong and the speaker had to retransmit..... kinda hard to "erase" half the word you heard right? CRC is only there to ensure the integrity of the file while it is being handled. It has nothing to do with timing. Most things in the digital domain are time independent.
To further illustrate the point, imagine what happens if the half of all the words sent to the digital to analog converter stopped for a second. Can we ask the DAC to wait? How does the DAC tell our ears to wait for the balance of the words????????

But to answer your question, YES, you can reduce jitter at the source but further down the road, you might get it back again depending on your hardware etc....

[BlackCatSound]

You are of course assuming that the material in question was converted into digital form using a totally jitter free ADC process.

[b-square]

Originally posted by BlackCatSound
You are of course assuming that the material in question was converted into digital form using a totally jitter free ADC process.

no, i'm assuming that regardless of how the adc was done, the best possible reconstruction will come with low jitter dac.


bb

[Sunsun22]

Noted the reasons. Another way get into my mind. Does buffer helps to reduce jitter? The CHORD 64 DAC says it has a buffer to reduce jitter. If this is correct, can we read the whole file to a buffer before playing?

[el`Ol]

Jitter can be corrected in advance, because there is "good jitter" (random) and "bad jitter" (regular), so you can cover bad by good jitter. You have to convert files to minimum twice the sample rate. I am quite sure modern sample rate use this technique and that is the reason why they have become popular in high-priced CD-players.