MP3 Decoding from flashcard without decoder chip

Easiest way is to get a USB SD reader.

Of course, you need USB host support on the PPC.

MP3s are files, not tracks, in most implementations.

Depends on the PowerPC. Easiest way is more likely to use GPIOs or the on-chip SPI controller, if they have any.

Yep of course. Sorry. So the controller would look through the files on the external file system reading header info from each mp3 file to determine track name / lenght etc. Right? Any links to how this is done in practice?

Yep the idea is to use the SPI for this purpose.

look for yampp d.

Yes, there is a header at the beginning of each mp3 file.

Same as reading/writing any files on the flash, usually FAT file system. Most OS would have FAT fs on USB drives/readers. You might have to do it yourself on SPI.

What is with this USB fetish?

Most OS that have a FAT filesystem would be properly designed, with a layered driver model. The filesystem driver would not care if it is reading from SPI or from USB or from anything else, for that matter.

As a point of order, a "USB" block device is really an ATAPI device on top of a USB transport layer.

Thanks but this implementati> Most OS would have FAT fs on USB drives/readers. You might have

So I require a fat32 file system on the controller which uses the SPI driver to read the files back. I should check the interface that the file system requires the SPI driver to support, right? I gather that NOT all file systems expect the same interface or is it OS dependant? Thank

Thanks but this implementati> Most OS would have FAT fs on USB drives/readers. You might have

So I require a fat32 file system on the controller which uses the SPI driver to read the files back. I should check the interface that the file system requires the SPI driver to support, right? I gather that NOT all file systems expect the same interface or is it OS dependant? Thanks

The interface between FS and block device driver is OS dependent.

If you are not using an OS, one free FAT filesystem for you to play with is mine,

Thanks for the quick response, and sorry all for the double post.

So what governs the API? Is it the vendor of the FS? If a file system is POSIX complaint then it is clear what the driver interface (open, read, etc.) will be right?

Thanks for the link; I'll at least look here to get more of a feel for the subject.

Thank all for helping my understanding.

Lewin,

And a great help it is! BTW some time ago I sent you some patches at zws.com for it (one involving pointer underrun is necessary); please let me know if you got 'em.

Regards,

Michael Grigoni Cybertheque Museum

Could be done, but not currently done for most os.

Implementations are os specific. USB storage devices with Fat/Fat32 are standard for Windows and Linux.

Hi!

I didn't get those. I have cyclic problems with antispam measures being enforced upstream of me. Some days I'll receive four thousand bounced spams that had zws.com/larwe.com return addresses. Some days I won't receive any mail at all. Please resend :)

I'm on shaky ground here, but I believe the answer to this is no. POSIX standardizes what the app layer sees. The way the OS talks to internal FS components is not part of this equation.

Windows XP has a token POSIX compliance, but XP device drivers, including installable file systems, are in no way compliant with any kind of published standard.