[quote]Originally posted by Mike Ghost:
<strong>A question. What's the difference between WAV files and AIF files. Now for longest time I thought Musical CD's use AIF files, but a friend of mine making a copy of musical CD for me said she made a mistake. She recorded it as MP3 file instead of standard WAV files to play in CD Players. I argued with her saying that it's AIF files. When I research on the Internet to find out which, I found something call standard "Red Book." Could some one clarify this for me?</strong><hr></blockquote>
don't flame me if i've skipped a bit... error correction research in progress,
but here's what i remember from my early audio days
Audio Interchange File Format (AIFF) - always 16bit 44kHz Stereo and always raw
was built for x-platform compatibility in CD playback decoders as well as software - predates
Windows Audio Video (WAV) which also does 16/44/S but later with codec/compression settings - i'll have to look up by how long.
Macs always did AIFF, even back in the day when the only other common format was SUN's 8 bit 11kHz mono .AU extension. PC's would read the same data as AIFF, but once processed and saved, the extension was changed to .WAV (hand of bill?)
There was a period where porting AIFF files to WAV files could be accomplished by just renaming the file. Macs using SoundEdit or other tools could easily read and write WAV files, but if they had been compressed (2:1 and 4:1 were available options at first) playback would sound thinner than the uncompressed version of either WAV or AIFF.
By the time Quicktime was launched in '90 compression options to trim filesize were more common in the storage of computer-accessed audio, but the CD-DA standard was still based on RAW - uncompressed audio as AIFF or WAV.
Red book was co-developed by Philips and Sony as the definitive standard of CD-Digital Audio. The physical specs of the mylarized platter were set and the data length of 74 minutes was the minimum duration required to hold what Sony considered the benchmark of classical music collections...
a specific recording of Beethoven's 9th as conducted by von Karajan with, IIRC, the NY Philharmonic. <a href="http://www.cdrfaq.org/faq02.html#S2-29
" target="_blank">see here for links... maybe part legend</a>
In order to licence the "'CD' logo", a disk must be 100% Red book 'compatible' and you will find some new stories out regarding certain copy-protection schemes which do not formally conform to Red Book and for which Philips intends to withold the right to call such a disc a CD.
Wav files are basically the same creature, and a music CD filled with AIFF will play the same as a music CD filled with WAV with a few small exceptions.
There are different encoding algorithms that will compress the raw audio data and generate a modified version of the output file. In the WAV world, the most common are PCM for Pulse Code Modulation (ok for CD Audio), and ADPCM for Adaptive Pulse Code Modulation (sometimes cranky). Sadly (thanks M$), the resulting compatibility of the output WAV differs.
Attempting to import WAV files into applications like Flash sometimes fails or generates timeshifts and poor playback. 99.9% of the time, the problem is the wrong codec has been used... running the WAV through a sound program to convert from PCM to ADPCM (or vice versa as required) usually fixes this.
Following on from Red Book were lots of new colours... Yellow, Orange, White, Blue, Green... for cd-rom, enhanced, philips CD-I technology, PhotoCD, etc... some details can be found <a href="http://osta.org/technology/cdr.htm#c
" target="_blank">here</a> <a href="http://osta.org/technology/cdqa.htm
" target="_blank"> and here in the FAQ</a> <a href="http://www.cdrfaq.org/
" target="_blank"> or here</a>
All later colours are supposed to be backwards compatible with earlier colours so that any device that can read, say, Photo CD, can by definition read CD Audio, or Multisession CD-XA.
Enhanced music CD's combine plain vanilla AIFF music with computer data on the same disc. The big trick with enhanced music CD's is that to play in a traditional Audio stereo, the first track must be music, not data (otherwise you'll blow your speakers with squealing infonoise).
At the same time, in order to have your computer think such a disc isn't just plain CDDA but actually has videos or lyrics (usually in a Macromedia Director front end), your computer needs the 'first' track to be FAT table-like file directory. Discussions of enhanced music CD's usually refer to their workarounds by the method of 'cheating' this information onto the disc in the form of "pre-gap", "half-gap" or similar.
MP3 data is a whole different animal as the decoding device isn't just a bitsampling laser, but now has to uncompress the MP3 stream with some CPU cycles, so unless your CD player has a clever chip in it (as some car MP3 players do), MP3 music is only usable for computer playback, and then it's fundamentally just a data disc and not technically an Audio CD, at least according to Philips and Sony.
for tons more technical info, including different block sizes per format, chemical analysis of the cyano- and other dyes used in making CD's (and their impact on data stability), and more, visit the comprehensive Optical Storage Technology Association website <a href="http://www.osta.org
hope this helps
(edit links added)
[ 07-10-2002: Message edited by: curiousuburb ]
[ 07-10-2002: Message edited by: curiousuburb ]</p>