Dynamic USB mass storage interface

[moldsvor]

I am working on a concept that would require a modified type of USB mass storage interface. I am not a software guy myself, so I would appreciate some feedback if the concept described below would be feasible. It would be great if someone could recommend a consultant with relevant experience that could develop a demonstrator of the solution.

The concept would need to use a USB mass storage interface to stream live content to e.g an amplifier with USB input. In general amplifiers would be able to play back most ordinary USB-drives with e.g. mp3 files stored. In order to stream live content, one would need to do a couple of modifications:
a) The host must be tricked into believing that the "file" (actually a virtual file) "goes on forever"'
b) The virtual USB-drive must be able to update the contents of the file while the host is reading from it, including meta information

It should also be possible to have multiple "files" on the virtual USB drive such that the host (e.g. an amplifier with remote control) can select between different live streams by using the "previous"/"next" controls.

1. Would such a solution (described below) be possible
2. How much of an effort/cost would it be to develop a demonstrator of the technique (on e.g. a microprocessor evaluation board)

Any feedback would be appreciated!

[Jan Axelson]

Every USB communication is between a device and a host. To communicate with USB drives and speakers, you would need USB host hardware and firmware. The host would need to support isochronous transfers for the speakers.

Perhaps you can store the data in multiple files and play, then delete, them in sequence.

An embedded Linux system would be one possibility:

http://www.lvr.com/embedded_host.htm

Jan

[moldsvor]

I think I thought this a bit differently: When plugging a USB pen into an amplifier, the amplifier would act as a master reading the contents from the USB pen. In my case the device would have to emulate a USB pen (being the slave) and play tricks with the file system in order for the amplifier as USB master device to never reach EOF.
The amplifier could then change to another "file" on the USB pen (or actually my device) in order to play another live stream.

This will work for master units that read until EOF before stopping. It might be more challenging if the master reads the file size first and stops when reaching that level.
One might not be able to find a really general solution that would work with ALL master units since one will be stuck with the software on the master unit.

[Jan Axelson]

If by "master" you mean "USB host," then yes, the same device/system with the amplifier could also contain the USB host hardware and firmware.

I think it would be easier to make something that works with files the conventional way rather than something that has to play tricks to implement something unconventional.

Jan