• Registered: 2010-12-28
  • Posts: 12

Topic: Infocast 8" Microphone

I was wondering if anyone could tell me how to access the microphone.

I tried via SSH

arecord -d 10 -f cd -t wav test.wav

but it was just an empty file no sound in it

Thanks
Jeff

  • Registered: 2010-12-29
  • Posts: 1

Re: Infocast 8" Microphone

I was wondering the same thing? I dont know of any application that uses what appears to be the microphone on the front of the unit.. has anyone confirmed it is even plugged in to anything on the hardware side?

  • Registered: 2010-12-28
  • Posts: 12

Re: Infocast 8" Microphone

I did open it up and a small 2pin cable is plugged in. did not remove bezel of lcd to ensure it was a mic

  • Registered: 2010-12-28
  • Posts: 12

Re: Infocast 8" Microphone

Anyone have an option I can try?

  • From: Orange County, CA
  • Registered: 2011-01-02
  • Posts: 5

Re: Infocast 8" Microphone

It looks like you need to set some things in amixer to get recording to work. Start with

amixer contents

to get a list of the controls. I've been able to record if I set the Mic Bias control to on, and set the Capture PGA switch to on. You'll probably want to boost the capture volume as well. Your IDs will probably be the same as mine, but double check them just in case:

# Set Mic Bias to on
amixer cset numid=10 on
# Set Capture PGA Switch to on
amixer cset numid=21 on
# Volume: Use some combination of Capture Boost Volume and Capture PGA Volume
amixer cset numid=18 2
amixer cset numid=19 50

Then arecord should give you sound (you might want to add in -vv to let you confirm levels as you record).

Where I am currently having difficulty is applying other recording output options. '-f cd' works, but trying to set any options manually seems to give incorrect headers for the audio data, and playback that is several octaves lower. Any ideas on that one?

  • Registered: 2010-12-28
  • Posts: 12

Re: Infocast 8" Microphone

Worked like a charm. Although I had to bump both the boost and cap volume to max to make it useable. Thanks so much.


What manual settings are producing that? Ill see what I can figure out.

  • From: Orange County, CA
  • Registered: 2011-01-02
  • Posts: 5

Re: Infocast 8" Microphone

I looks like the main problem I'm having is with is the channel parameter. 

arecord -vv -t wav -f U8 -c 2 -r 11025 test.wav

records fine, but 

arecord -vv -t wav -f U8 -c 1 -r 11025 test.wav

gives me an octave-down effect. Using -f S16_LE gives me problems with -r 22050, -r 8000, -c 1, etc., but 16-bit is probably overkill so I'm not as concerned.

Seeing as how the mic on the Infocast is mono, recording one channel of nothing seems like a waste, especially given the limited resources available on the device.

  • Registered: 2010-12-28
  • Posts: 12

Re: Infocast 8" Microphone

I tried a few before you posted without setting rates and channel#
All of mine were consistently higher octaves(chipmunk style).
the -f cd option was the only one to produce sound close to actual.
I would almost bet there is a problem with the compression codec.

I did run into a snag though. I thought the WM8961
was a full duplex chip however when I applied the settings it killed sound


Two options I can think of off the top of my head would be bridge the linput and rinput leads on the chip

or

pipe the sound to an encoder like lame

9 Reply by nightsbird (edited by nightsbird 2011-01-03 08:33:20)

  • Registered: 2010-12-28
  • Posts: 12

Re: Infocast 8" Microphone

arecord -v (Might have some insight)

RIFF$ÿWAVEfmt @dataÿRecording WAVE 'stdout' : Unsigned 8 bit, Rate 8000 Hz, Mono
Plug PCM: Linear conversion PCM (S16_LE)
Its setup is:
stream       : CAPTURE
access       : RW_INTERLEAVED
format       : U8
subformat    : STD
channels     : 1
rate         : 8000
exact rate   : 8000 (8000/1)
msbits       : 8
buffer_size  : 4032
period_size  : 1008
period_time  : 126000
tick_time    : 0
tstamp_mode  : NONE
period_step  : 1
sleep_min    : 0
avail_min    : 1008
xfer_align   : 1008
start_threshold  : 1
stop_threshold   : 4032
silence_threshold: 0
silence_size : 0
boundary     : 2113929216
Slave: Hardware PCM card 0 'SILVERMOON WM8961' device 0 subdevice 0

Its setup is:
stream       : CAPTURE
access       : MMAP_INTERLEAVED
format       : S16_LE
subformat    : STD
channels     : 1
rate         : 8000
exact rate   : 8000 (8000/1)
msbits       : 16
buffer_size  : 4032
period_size  : 1008
period_time  : 126000
tick_time    : 0
tstamp_mode  : NONE
period_step  : 1
sleep_min    : 0
avail_min    : 1008
xfer_align   : 1008
start_threshold  : 1
stop_threshold   : 4032
silence_threshold: 0
silence_size : 0
boundary     : 2113929216
  • Registered: 2010-12-28
  • Posts: 12

Re: Infocast 8" Microphone

I built ogg and speex and piped raw into it using this

arecord -d 10 -f S16_LE -r 8000 -t raw | speexenc --le --16bit --rate 8000 --stereo - /mnt/storage/test2.ogg

The sound was about spot on except it output

Recording raw data 'stdout' : Signed 16 bit Little Endian, Rate 8000 Hz, Mono
Encoding 8000 Hz audio using narrowband mode (stereo)
overrun!!! (at least 157.131 ms long)
overrun!!! (at least 120.376 ms long)
overrun!!! (at least 114.634 ms long)
overrun!!! (at least 5.743 ms long)
overrun!!! (at least 2.132 ms long)
overrun!!! (at least 112.745 ms long)
overrun!!! (at least 9.566 ms long)
overrun!!! (at least 121.684 ms long)
overrun!!! (at least 7.929 ms long)
overrun!!! (at least 114.624 ms long)
overrun!!! (at least 4.777 ms long)
overrun!!! (at least 113.773 ms long)
overrun!!! (at least 7.037 ms long)
overrun!!! (at least 28.974 ms long)
overrun!!! (at least 0.136 ms long)
overrun!!! (at least 95.947 ms long)
overrun!!! (at least 118.006 ms long)
overrun!!! (at least 112.795 ms long)
overrun!!! (at least 0.790 ms long)