Re: Controlling and reading a usb radio

[Deron <de...@pa...>]

On 5/7/12 4:13 PM, Peter Stuge wrote:
> Deron wrote:
>>>>         bInterfaceClass         1 Audio
>>>>         bInterfaceSubClass      2 Streaming
>>> Those two interfaces are standard USB classes, meaning a generic
>>> usb audio driver should be able to handle it already.
>> Thanks for the info. What would be the easiest way to pull audio
>> data from it then?
> What do you want to do with the audio data?
>
> You do not need to consider the fact that this is a USB device at all
> beyond the interaction with the HID class interface, the device
> appears as a sound card in your system. Try:
>
> cat /proc/asound/cards
>
> Run alsamixer or similar to set mixer controls, and an audio
> recording software to record audio.
>
>
> //Peter
>

I guess I know less about Linux audio then I do USB!

Indeed, it shows:

  1 [Radio          ]: USB-Audio - ALERT FM Radio
                       Axentia Technologies AB ALERT FM Radio at 
usb-0000:00:1a.1-1, full speed

I realize this may be beyond the knowledge of this list, but I'll 
explain anyway. I'm just looking for the pcm audio stream (be it 16bit, 
2 channel or whatever) so that my code can look for the audio tones that 
precede the EAS (the Emergency Alert System used in Canada and the US to 
broadcast severe weather warnings and other emergency notifications) and 
act accordingly. So opening a device/pipe is perfectly acceptable. 
Recording to disk and then checking it after the fact would be a bit 
difficult, but I suppose the tools might let me pipe it to my 
application(?).

I'm guessing I need to look into ALSA?

Deron