Audio files are bad, no they're good, no they're bad, no they're ....

Question

I downloaded some classical music (yes I paid for it) in the form of an mp3 file (Rachmaninoff: 24 Variations on a Theme of Paganini) - I am giving a lecture on this music and wanted to segment it into the theme and the 24 variations, 25 sections in all. I imported it into FCP5, opened it (the soundtrack) in the viewer, then placed the 25 markers along its length. Then I set in and out points at each marker and created 25 new clips. I then pulled each of these sub-clips, one at a time, into the Timeline, rendered each, and exported each to a new folder. I then opened iTunes, created a new playlist, and copied the clips into the new playlist, then burned them onto a CD. The result was not very good - it sounded as if I had "dropped frames" (is that the same in audio, dropped frames?) - there were discerible breaks in the music as I listened on the CD, not acceptable for even casual listening, much less lecturing. The original file sounds quite good, nothing wrong with it. The breaks in the continuity of the music in the CD clips occur sporadically along the course of the music on each.
Since I also have Soundtrack Pro, I went back to the original file, opened it into Soundtrack Pro, cut the music into the same clips there, and sent the saved clips to a new folder. When burned to a CD they are perfect, not a defect to be heard.
I do notice that the exported files from Soundtrack Pro are wave files (I selected that formet), and the exported files from FCP5 are apparently movie files (the "Get Info" screen identifies them as movie files, DV/DVCPRO NTSC Integer (Big Endian), Timecode 720 X 480.
Since the "movie files" did manage to make it onto the CD and play at all, they obviously work, but not very well. So I have some questions:
1) if I had incorporated these audio clips into a real movie as the soundtrack, and exported the final film onto a DVD would I have had the same problem?
2) if I had exported these audio only movie files onto a DVD disk instead of a CD would that have made a difference?
3) what's so "right" about WAVE files?
4) could I have exported the individual clips in some other audio format (.wav?) other than the native movie file - I should emphasize that I did choose "soundtrack" under the "Export file" command in FCP5! I didn't see any other choices.
I'd really like to understand what is happening, I have a lot of editing to do in the near future and audio was always my nemesis (video is so simple by comparison) when I used and XP system.
Barry

Answer 1

Thanks. I am new at this. Your kind answer prompts another few questions:
1) when I buy music from iTunes, they arrive in .mp4 format (my Rachmaninoff was purchased from eMusic and they use .mp3). I notice that neither FCP5 nor Soundtrack Pro (by the way, Soundtrack Pro is bundled with FCP5 when purchased) seems able to read ("open" and "import" won't work) the .mp4 format. And neither will convert the format, I get an error message that it's been encoded with a protective code and cannot be edited. However, I am able to burn the .mp4 file to a CD, then import the file from the CD back into the hard drive, and import it into Soundtrack Pro or FCP5. What kind of "protection" is that, and why am I being restricted and forced to use this labyrinth technique to be able to edit my sound file that I bought, paid for, and own?
2) I also note that in Soundtrack Pro I have a choice of several formats to export to - both AIFF and WAVE seem to be compatible with FCP5 - the manuals that came with FCP5 define the different file formats, but don't really suggest one or the other as superior. I notice that some file formats have special uses, like crossing over to another audio system, that doesn't apply to me as I am only using FCP5 and iTunes. So is there a real difference between AIFF and WAVE that should make me favor one over the other? I get the feeling (from the manual) that AIFF is preferred, I just want to understand why (if that's true).
3) still curious about my other question in the original questions: would the FCP5 generated "movie files" (that have only audio, no video) have worked OK if I had burned them to a DVD disk instead of a CD?
Again, thanks in advance.
Barry
Mac G5 Mac OS X (10.4.8)