I have a Leopardboard 365 loaded with the RR Leopardboard Free SDK. I am able to stream (gstreamer) audio from my host to the Leopardboard and hear it through headphones attached to the audio-out jack. I can also hear audio produced by the audiotestsrc locally through the same headphones.
I can't, however, get the microphone attached to the audio-in port to work. The simplest gstreamer pipeline should work,
gst-launch alsasrc ! alsasink
but nothing is heard, though gst-launch reports no errors.
So, what am I missing? Does the audio-in port support simple microphone input or is it expecting some other type of input device? Is there some specific hardware device i need to specify to alsasrc? Do I need to use one of the TI elements?
Thanks for your help!
At this point the 'mic input' is working more like a 'device input' since the bias voltage for the microphone is disabled (even if you enable it writing the TVL320AIC3104 register).
Pablo BarrantesEmbedded Software EngineerRidgeRun
We tested by connected an mp3 player or a PC audio out to the leo365 board. Microphones are tricky. You might be able to play with the AIC registers using i2c-tools to find the proper settings for your microphone, then update the driver to support your configuration.
You can see how we tested audio in at
Thanks Todd and pablo,
I have it working with a DVD player as my audio input.
Now, is there a way to eliminate some of the REALLY loud "background" hum I'm hearing?
Sounds like a ground loop. Try a battery powered mp3 player.
Also, you can try running 'alsamixer', find the AGC option and activate it (use the 'm' key for that).
That might reduce the noise you're hearing
No, AGC doesn't reduce noise. AGC makes noise louder.
Looking at the schematics of Leopardboard and TI's EVM board shows that the Audio Line has been completely removed in Leopardboard and the Audio jack on the Leopardboard is in fact the Mic line.
Leopardboard 368 - Audio Line
EVM368 Audio Lines
As I know the difference between a Mic input and an Audio Line-In, is the biasing voltage which turns the microphone on and received the audio signal.
So it seems that the problem is probably in the software settings.
For more information you can check TI's EVM board documents: