Support and General Use > Hardware
Presenting iPod as a standard USB mass storage device for in-car use?
gevaerts:
--- Quote from: NiHaoMike on April 02, 2010, 05:15:31 PM ---Is there anything wrong with using a generic mass storage ID?
--- End quote ---
There is no such thing.
Llorean:
The IDs belong to other companies. There's no such thing as a "generic mass storage ID." They identify the vendor and product of the device.
We contacted the USB-IF and were told that even though we implement our own USB code, we do not need to purchase our own USB IDs because we're using the original ones of the device.
If we were to start identifying as devices other than that which the player actually is (in terms of vendor ID and product ID) we would likely then need to purchase our own ID as the alternative one. This is expensive.
bifter:
What about using the ID of an alternative manufacturer then? Is this illegal?
Is my example of browser agent switchers different? Firefox for example has an extension that fools Web sites into thinking that your browser is IE or Opera, etc.
If it were permissable I think this would be a useful feature. Not just for circumventing the VAG head unit parsing (if indeed this is what is happening) but I should imagine there might be other uses for it.
gevaerts:
--- Quote from: bifter on April 02, 2010, 05:38:18 PM ---What about using the ID of an alternative manufacturer then? Is this illegal?
Is my example of browser agent switchers different? Firefox for example has an extension that fools Web sites into thinking that your browser is IE or Opera, etc.
If it were permissable I think this would be a useful feature. Not just for circumventing the VAG head unit parsing (if indeed this is what is happening) but I should imagine there might be other uses for it.
--- End quote ---
It's not illegal. If we would do this, the USB-IF might not be happy about it, but since we didn't sign any document they can't do much about it. From a technical point of view I really don't like it though. If a host refuses to believe that a device is Mass Storage because of its VID/PID, that host is broken.
Your browser user agent analogy does make some sense. These things can trick broken webservers into serving you content anyway, but they will also trick well-working webservers into giving you content that doesn't work because it was tweaked for the browser you now pretend to be (possibly to work around bugs in it).
Suppose you want to format and reinstall rockbox, so you plug it in, format the disk, and then run Rockbox Utility. How is that supposed to find out which player you have if you've changed the USB IDs?
bifter:
--- Quote ---If a host refuses to believe that a device is Mass Storage because of its VID/PID, that host is broken.
--- End quote ---
In this case it seems the manufacturer may have broken it deliberately. It would be pretty typical of Apple's approach to things and I guess VAG get some kind of kickback from the sale of iPod connectors?
--- Quote ---Suppose you want to format and reinstall rockbox
--- End quote ---
Are you saying the tags are coded into the firmware? I guess I don't understand the technicalities but, if this is the case, does the utility not look at the Apple firmware to ascertain the model anyway? I'm guessing that these ID tags are still there as when I boot into Apple OS the head unit still rejects it.
In any case would there not be another tag that could be set and picked up by the Rockbox utility such that it would recognise that the IDs have been changed and prompt the user to manually select the player? Just a thought.
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