[Flac-dev] Support .cda as input files

[Steve Fosdick]

On Fri, 14 Sep 2007 01:10:09 +0200
"Harry Sack" <tranzedude at gmail.com> wrote:

> does anybody know why dvd use files for audio and video but audio cd's not?
> What could be the reason for this?
> e.g. they could make a file for each track and just put them on an
> audio cd and make cd players compatible with this format. So for me it
> has always been a mystery why audio cd's work this way.

My best guess is that at the time CD audio was designed computers (which had the concept of files and a filesystem) and audio equipment were pretty much separate camps.

So when the CD audio format was designed the reference the designers had was the LP record. They made a format that had a continuous stream of data in a spiral around the disk, just like the LP has a continous groove, and which can be divided into "tracks" which hold songs or movements.  The new part of the CD format was a way to encode PCM (digital) audio with error correction onto optical media.

It was only later that the computer industry realised that the disk could also be used to hold data and, because it was cheap to make and the player technology was well understood, would be economicly viable.  So a standard for putting data "sectors" onto the CD media with extra error correction was developed and a corresponding standard for laying out the filesystem within the available storage (ISO 9660).

There is also the fact that a CD player was expected to implemented in hardware or with a very simple processor so the format had to be simple.

By the time DVD was being designed (and it's subequent sucessors to be) CD-ROM has been around for a while and DVD players were expected to have internal software that could cope with the complexity of working with a filesystem on the disk rather than a simple data stream.

Steve.