[AndrewZander]

Greetings!
 
I was wondering if someone could tell me how burning hi-res (i.e., 24/96) audio files to a CD would work. 
 
For example, what determines which data is copied to the CD and which data is not? Is this process 'smart' enough to know what data should and should not be written to the CD?
 
Would doing this result in essentially the same data that would be found on a commercial CD of the same album?
 
Obviously copying hi-res audio to a CD sort of defeats the purpose of having hi-res audio files, but sometimes it's convenient to have a CD for compatibility purposes. 
 
Thanks!

 

[esldude]

If what you want is to put hirez files on a CD so you can play them back on any regular CD player then they will have to be downsampled.
 
For instance a 192 khz sample rate at 24 bits will need converting to 44.1 khz sample rate, and dithered to 16 bits. 
 
There is software to do that.  I am pretty sure some good burning software will do it on the fly for you. 
 
Within the ability of 44.1/16 yes it will sound the same.  You are losing ultransonic frequency response, and the low level noise may be raised though likely not enough you will notice.  The real benefit of re-mastered or re-released Hirez material is that it has been or may have been more carefully mastered.  That will still show through on CD. 
 
If you can give a little detail about whether you are on Windows or Mac or Linux, and if this is what you have mind to create CD playable copies then we could be of more assistance.
 
 
If on the other hand you are wishing to put the whole hirez file on a CD without downsampling, you can only do that by placing it there as a data file.  It won't play on an audio CD player.  But any computer could read that data file and play it back. 

 

[AndrewZander]

  If what you want is to put hirez files on a CD so you can play them back on any regular CD player then they will have to be downsampled.
 
For instance a 192 khz sample rate at 24 bits will need converting to 44.1 khz sample rate, and dithered to 16 bits. 
 
There is software to do that.  I am pretty sure some good burning software will do it on the fly for you. 
 
Within the ability of 44.1/16 yes it will sound the same.  You are losing ultransonic frequency response, and the low level noise may be raised though likely not enough you will notice.  The real benefit of re-mastered or re-released Hirez material is that it has been or may have been more carefully mastered.  That will still show through on CD. 
 
If you can give a little detail about whether you are on Windows or Mac or Linux, and if this is what you have mind to create CD playable copies then we could be of more assistance.
 
 
If on the other hand you are wishing to put the whole hirez file on a CD without downsampling, you can only do that by placing it there as a data file.  It won't play on an audio CD player.  But any computer could read that data file and play it back. 

Thank you for your response!
 
I'm using a Mac, and what you describe is exactly what I have in mind. 
 
Are there any recommended apps/methods that accomplish this task better than others? I have some limited experience with Audacity, but it would seem that this program would be able to accomplish the task of downsampling the audio file to 16/44.1 in order to burn it to a CD.
 
Thank you!

 

[esldude]

Yes, Audacity would do the conversion for you.  There are probably better bulk converters or burning programs that do it as part of the burn.
 
I am not a Mac user, so one of them would probably be better able to recommend software to you. You could look at www.sourceforge.net and see what is available for Mac.  Those will be free, so other than trying it out no cost. 

 

[limpidglitch]

  Thank you for your response!
 
I'm using a Mac, and what you describe is exactly what I have in mind. 
 
Are there any recommended apps/methods that accomplish this task better than others? I have some limited experience with Audacity, but it would seem that this program would be able to accomplish the task of downsampling the audio file to 16/44.1 in order to burn it to a CD.
 
Thank you!

 
If you already have your music organized in iTunes there is no reason not just to use it for this task as well. A good alternative, and a real Mac stalwart, is XLD. Very handy for all sorts of audio conversions.
Feinschmecker will tend to use SoX, though if you're not comfortable with Terminal and MacPorts, I wouldn't bother.

 

[AndrewZander]

   
If you already have your music organized in iTunes there is no reason not just to use it for this task as well. A good alternative, and a real Mac stalwart, is XLD. Very handy for all sorts of audio conversions.
Feinschmecker will tend to use SoX, though if you're not comfortable with Terminal and MacPorts I wouldn't bother.

I wasn't sure iTunes was a better solution when it comes to downsampling the audio files, but yes, using iTunes would certainly be convenient. 
 
Thank you for your response.

 

[limpidglitch]

   
 
For example, what determines which data is copied to the CD and which data is not? Is this process 'smart' enough to know what data should and should not be written to the CD?
 
 

 
Monty over on Xiph.org (and intermittent poster at this forum) has made a nice video explaining the quantization (xBit to yBit) part of that.
If that doesn't satiate your curiosity there is a nice article on Wikipedia. Personally I find all the integral equations and talk of entropy a bit intimidating, but it is easily ignored.
 
The downsampling (or upsampling, essentially the same, just in reverse) is rather simple. 
 
If we take 96kHz to 44.1kHz as an example:
 
The least common denominator of 96 and 44.1 is 14112. (96x147 = 44.1x320 = 14112)
 
First step is to multiply the 96kHz stream by 147. Imagine beads on an elastic string, pull the string to 147 times its original length and fill the equal sized spaces between the beads with empty bits, or zeros.
Second step is to apply a low pass filter at half the sampling frequency of the frequency you are sampling down to. (44.1kHz/2 = 22.05kHz)
Third step is to divide the intermediate stream by 320. If you have that long string of beads, it would be like starting at a random place and go along picking every 320th bead, and throwing away every bead in between.
 
That is downsampling, simplified.

 

[limpidglitch]

  I wasn't sure iTunes was a better solution when it comes to downsampling the audio files, but yes, using iTunes would certainly be convenient. 
 
Thank you for your response.

 
I see no rational reason for why Apple shouldn't have this process well figured out, after all it isn't witchcraft, just maths.

But if you want it confirmed you can do a dry run and compare files.
If if you choose AIFF under Import Preferences and 44.1/16 you can afterwards ctrl-click any track and click Make AIFF-version.
Compare blind using ABXer for that true objectivity.