Noisy audio input on Jetson TK1

Hi,

We have been trying to record a audio from the audio input jack by giving a line in from an external source like a mobile phone. When recorded using arecord the output is very noisy and we can barely here the audio.

Further if we do not play anything also we hear a noise.
Are there any drivers or any software issues that we might have missed? We currently have installed the driver package from the nVidia.

Please help us.

Thank you !

There are a lot of things which could affect audio. Here’s something I’ve used in the past on the JTK1 microphone jack:

amixer cset name="Stereo ADC MIXL ADC2 Switch" 0
amixer cset name="Stereo ADC MIXR ADC2 Switch" 0
amixer cset name="Int Mic Switch" 0
amixer cset name="ADC Capture Switch" 1
amixer cset name="RECMIXL BST1 Switch" 0
amixer cset name="RECMIXR BST1 Switch" 0
amixer cset name="RECMIXL BST2 Switch" 1
amixer cset name="RECMIXR BST2 Switch" 1
amixer cset name="Stereo ADC L1 Mux" "ADC"
amixer cset name="Stereo ADC R1 Mux" "ADC"
amixer cset name="Stereo ADC MIXL ADC1 Switch" 1
amixer cset name="Stereo ADC MIXR ADC1 Switch" 1
amixer cset name="Stereo ADC MIXL ADC2 Switch" 0
amixer cset name="Stereo ADC MIXR ADC2 Switch" 0
amixer cset name="IN1 Mode Control" "Single ended"
amixer cset name="IN2 Mode Control" "Single ended"
amixer cset name="Mic Jack Switch" 1

arecord -t wav -c 1 -d 4 -v tmp.wav
aplay tmp.wav

If there is a mismatch between sample rate and playback you can expect some pretty horrible sounds. In more subtle cases it can be nothing more than EMI from another copper trace (square waves are the ultimate in spikes of EMI). More description of the noise would be of use, though if you could post a copy of a file somewhere with the actual audio it might help more.

Thanks for the answer!
We changed the sample rates and tried. But thew problem was there.
Finally we tried changing gain level in alsamixer and we reduced all the boost levels and a decent sound now can be recorded.