Music CDs

[monkey0506]

Why must the .CDA (CD Audio -- This is the file type your music is converted to when you burn it to CD) file type be so huge?  I have 1.14 GB of music (which lasts several days) on my hard drive, which I am backing up to CD (so I can format cause my comp is screwed up) but anyway, I've noticed that if I had tried to save my music as a music CD (one playable from say, a CD player) it would take at least like 5 or 6 CDs (actually, I just calculated it, and it's 12 (11.1-something)), but burning it as a data CD (since it's just a back up), I can fit it onto two.  I think this file format needs a revamping...

Well, I think that's about it.  I'm burning the last CD now, and then I'm going to format.  If you really have to know why, I'll tell you later once I get it running again.  (Which is why I'm taking 4 CDs to make a proper backup of all my stuff.)

[Gilbert]

What are the format your 1+ GB music originally in? MP3? OGG?

Note that CD audio is standardized to uncompressed 44,100 Hz 16-bit stereo PCM.

So, one second of CD audio takes about:
44100*2*2 = 176400 (bytes) ~=172KB
(that's why 1X CD reading speed is about 150KB/s, first *2 is 16 bit, second *2 is stereo)

so, one minute of audio is about:
172 * 60 = 10335 (bytes) ~= 10MB
So for a normal CD it can hold about 1 hour of audio (well max 74 minutes for standard media, not coutning overburnt CDs).

Note also that it's not a file format. CD audios are raw data written into tracks, those .CDA file visualizations is just the crappy way of displaying them in file manager under Window$.

If you're just backing up the files and are not going to have them played with standard CD players, just backup the original files.

[TheYak]

Yep, CD-Audio is handled different ways by different file systems.  For XP/NTFS, the .CDA files are just shortcuts to the RAW data.  If you were to copy the CDA's from an audio CD, you'd end up with a dozen KB of useless files.  In other OS's, the CDA's might be displayed at their actual RAW filesize but it's still just a designator showing the different tracks and the space they take up. 

CDA-burning isn't determined so much by the initial size as the time of play.  If I have a full 74 minutes of crappy 64Kbps .mp3s, and the same 74 minutes of 192Kbps files, it'll be the same space consumed on an audio CD, at the same khz (44.1), stereo & 16-bit..  the 64kbps files will just sound crappier.   If you need to backup the music just for archive purposes, it ought to fit neatly on 2 cd's.. otherwise, the number of discs will be determined by the total length (time) of the tracks.

[LGM]

I think your grasp on audio files is completely lacking...

An Audio CD is it's won file system. Those .cda's you see are links, as was said before, to actual "tracks" on the CD. These tracks hold the song. The reason the song is so big is because it's RAW audio.. No compression at all, which takes up alot of data. The average song roughly equals about 50MB. So naturally, when you pack them up as a real audio CD, it would take a considerably larger amount of CDs to back up then if you were to make a normal data CD.

It's nothing anyone can "improve." An unompressed 44.1khz audio file will always be big. Unless CDs somehow incorporate FLAC, a lossless compressor, you'll just have to back up your MP3s with a data CD. (It takes me 12 CDs to back up mine o_0)

[Snarky]

Monkey_05_06, are you really unaware that MP3s (or OGGs, WMAs, M4Ps or whatever file format your music is in) use lossy compression? That the reason they're able to get the music files so small is that they cut out parts of the sound and distort others? You may not hear the difference, but they are not the quality of the original files.