Hello Everyone,

In my new job I've been assigned to create a proof of concept "mp3 player" using an existing product from our company. Trouble is, I've not done anything with audio before and the timeframe is tight. I guess my new boss thinks it's a piece of cake - "it's only software, after all, right?" The main problem is that this Linux-based device doesn't have _any_ audio capability so we're having to engineer something. The current plan is to connect a fancy Bluetooth (CSR BC5) chip and use it for the audio-output stage.

Although I don't think this forum is necessarily the right place to go looking for help, I'm hoping someone can point me in the right direction for where to get some education. I really don't understand the finer points of how the audio signal gets to the device driver and this is where some help would be appreciated. Specific questions I have are:

What's the general flow of the data from the disk file (or streaming audio source) to the device driver? Is it: MP3file -> streaming software -> codec -> driver or// MP3file -> streaming software -> Codec -> streaming software (e.g. via callback) -> driver? (or does it even have a standard approach?)
The Bluetooth part can be connected by UART or USB to the host. USB would be better because the BT part enumerates as an audio-class device. This would probably solve my problem, but our Linux device hasn't an available host-side interface, I'd have to delve into USB OTG and maybe cut and jumper some traces. That leaves UART. I don't see how a UART can be made to look like an audio device unless I write a driver that presents as an audio interface to Linux and exchanges the audio traffic between user space at the top-end and the UART on its bottom-end. Is there an easier way to create an audio interface out of a UART?

I've downloaded several packages to take a look at how they implemented, but they all contain dozens (or hundreds) of files. Progress through will be slow, but I'm guaranteed to find an answer. I've got copies of:

gstreamer
MuSE
madplay

Between the three of these I think I'll be able to figure something out (needs to be ported to ARM9). Is anyone able to make a recommendation?

Thanks for reading this post - I promise not to be a pest on this list (but would be happy to share my eventual solution, if anyone wanted to know it)

Regards,

Pete Moss.