Music CDs

[secsee1]

When you buy a music CD what format are they recorded in? the reason I ask this is because a shop bought CD of say 12 tracks seems to take up all of the playing surface, but yesterday I purchsed a downloadable album online which I assume was delivered in mp3 format but when I burnt it to a CD disc the amount of playing space it took up was tiny.

[ChuckFickens]

They aren't in a format as such (not from a normal computer point of view anyhow)

They are in PCM audio which is basically a digital representation of an analogue audio wave
http://en.wikipedia.o...Pulse-code_modulation

The closest format in a computer sense would be a WAV file.

[gingejbee]

Music CDs hold a maximum of about 80 minutes. I've just looked at some (don't forget they play from the centre outwards) and they do not have the whole surface recorded - look at some particularly short ones, say 50 minutes.

[Gromit]

They are in .aiff format which is uncompressed. They usually take up about 35Mb per track. .Mp3s and .mp4s use compression technology to reduce the file sizes dramatically to 5Mb for the same track. So a cd will hold about 18 tracks in audio that hi-fis can play but over 100 tracks in compressed data files that your computer can play.

http://en.wikipedia.org/wiki/Audio_file_format

[ChuckFickens]

"They are in .aiff"

No they are not.

A CD hasn't got a file system on it to have a file format of any type, you can't really directly compare audio on a CD to any type of file.

[secsee1]

Thanks for all of you're interesting answers, you learn something every day as they say, so If I burnt a disc in "Wav" format would this take up more of the playing/recording area of the CD & more importantly will a disc made in this format play on a normal home CD player ?

[ChuckFickens]

Wav files can be compressed, but generally are not, so if you burnt a CD with uncompressed WAV files on it at the same sample rate and bit rate as an audio CD (basically the same quality) then yes, the WAV files would take up about the same amount of space as raw audio files. (the may be minor differences due to differing overheads)

Some CD players would play them, some wouldn't, some might depending on such things as file name lengths, folder structures etc, there is no common standard for that sort of thing.

However, you'd get no benefit from turning a MP3 into a WAV to put it on CD, doing so wouldn't add quality to the audio that wasn't already there.

If you want to put your MP3s onto a CD so any CD player can play them then your best bet by a long way is to use something like windows media player, or nero burning rom (or loads of other burning programs) to actually burn the CD as a proper audio CD rather than a computer CD with audio files on it.

[Gromit]

ChuckFickens and secsee1

FYI

http://www.fileinfo.com/help/cd_audio

[ChuckFickens]

From that link.

"Therefore, the audio format used for CD audio tracks does not correlate directly to an computer audio file type."

[VHG]

>>>when I burnt it (mp3) to a CD disc the amount of playing space it took up was tiny.

When creating a "music" CD from mp3 files you can either put them on the CD in "data" format (so they stay as mp3) or in "Audio" format where they are changed to the format that can be used in normal home CD players.

The actual terms may vary from one CD maker to the other, but basically create a music CD from these mp3 files and choose "Audio" format (or similar) before making the CD.