Joachim Backes > Weird: Inserting an audio CD, then clicking (inside the desktop) with > nautilus on the computer icon and then on "CD/DVD Drive: Audio Disc", > the next nautilus window shows a window with title: "These files are > on an Audio CD." with a file list like "Track 1.wav", "Track > 2.wav",... > > You may see the nautilus window at: > "http://www-user.rhrk.uni-kl.de/~backes/UL/nautiluswindow.jpg"; Yes, I know. Did you actually read what I said? It's faking it. Audio discs are not mountable, and have never been mounted. Nautilus is giving you an interface that pretends. Some other things can do the same trick. The clue is when not everything can do it, because their file chooser gadget only reads the actual directory tree, and doesn't interact with the handler. And, when you list all the "mounted" file systems, it's not present. There is no file system, nor "files" on a compact audio disc. There are no wave files. There isn't even audio data streamed on the disc in a manner similar to a wave file. There's a table of contents (TOC) at the start of the disc that says how far in, and how far for, each track is located. Then there's a stream of encrypted audio data. It's encrypted, in a non-secret way, for error handling (*). There's enough spare space in the track audio data that some people have included a tiny bit of text so that the track title can be shown on the player. All of which requires a handler to give you an interface to it. When you double-click on a fake wav file in Nautilus, it could start playing the disc in any number of ways, depending on what command is associated with the action. Send a play command to the drive, and let the drive output audio. Send a play command to a CDDA player program. * Audio for a compact disc is a pulse code modulation (somewhat similar to a wave file), in a sequential continuous left audio, then right audio, sequence. *BUT*, it's then scrambled using an old military encryption scheme, for error handling. And put onto the disc in that form. If it were unscrambled, then missing data would have large dropouts in the audio. Imagine this email where the middle paragraph was lost, you'd have no way to know what was there to reproduce it. But if you pre-scrambled it in a defined way, then a large blob in the middle of that scrabled data going missing in transit is only going to be a few letters in each word, scattered throughout the message, when unscrambled. It's reasonable easy to work out what a missing letter ought to be, and fake the missing letter. Of course, it's not 100% accurate, but far less noticeable than dropouts on linear data, where the equivalent of whole words regularly go missing, and larger segments a bit less often. In the case of an audio signal, if at one moment the audio was 1.435 volts, then there was a missing bit, then the next moment the audio was 1.437 volts, the error correction could reasonably replace the missing moment with 1.436 volts of signal (half way between the two existing bits of data). Rather like repairing a broken step on a staircase, you have the adjacent steps as a guide to what ought to be between them. For what it's worth, it's quite common that audio discs play back through a mass of continual errors, but you never notice it (if your player isn't crap at error handling). It's one reason why some discs are damn near impossible to rip, but apparently play fine (ignoring deliberately broken discs, by the manufacturers, in an attempt to thwart copying). -- [tim@localhost ~]$ uname -r 2.6.27.25-78.2.56.fc9.i686 Don't send private replies to my address, the mailbox is ignored. I read messages from the public lists. -- users mailing list users@xxxxxxxxxxxxxxxxxxxxxxx To unsubscribe or change subscription options: https://admin.fedoraproject.org/mailman/listinfo/users Guidelines: http://fedoraproject.org/wiki/Mailing_list_guidelines
![http://www-user.rhrk.uni-kl.de/~backes/UL/nautiluswindow.jpg"](http://www-user.rhrk.uni-kl.de/~backes/UL/nautiluswindow.jpg"){kind=link}
