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I have a Raspberry Pi B+ model and I am using a USB sound card to record audio. The problem is that I am only getting static and loud humming when recording, with nothing else actually recorded. I am having the exact same issue as described here, only he has a B model.

I have tried a few different asound.conf files, and restarting alsa, but it did not make a difference, other than restricting what formats I can record in.

I can play back the standard sounds on raspbian through the speaker/output/earphone jack on the USB sound card, which plays back fine.

The two USB sound cards I have tried are both C-Media based chipsets:

  1. 7.1 Channel USB External Sound Card Audio Adapter
  2. Virtual 5.1: I cant post more than two links, so search Amazon for "Virtual 5.1-surround USB 2.0 External Sound Card"

I have tried different ways to record via the mic and aux plugged in. I have tried different rates and formats:

pi@pi-roshnee-lm ~/pi_scripts $ arecord -f S16_LE -c1 -r44100 -t wav test.wav
Recording WAVE 'test.wav' : Signed 16 bit Little Endian, Rate 44100 Hz, Mono
pi@pi-roshnee-lm ~/recordings $ arecord -D plughw:0 -r 48000 test.wav
Recording WAVE 'test.wav' : Unsigned 8 bit, Rate 48000 Hz, Mono
pi@pi-roshnee-lm ~/recordings $ arecord -D plughw:0 -r 16000 te st.wav
Recording WAVE 'test.wav' : Unsigned 8 bit, Rate 16000 Hz, Mono
pi@pi-roshnee-lm ~/recordings $ arecord -f S16_LE -D plughw:0,0 -r 48000 test.wav
Recording WAVE 'test.wav' : Signed 16 bit Little Endian, Rate 48000 Hz, Mono

I have tried pulling the mic out slightly, which as no effect

I have tried switching to USB1.1, which has no effect:

pi@pi-roshnee-lm ~/recordings $ cat /boot/cmdline.txt

dwc_otg.lpm_enable=0 dwc_otg.speed=1 console=ttyAMA0,115200 console=tty1 root=/dev/mmcblk0p2 rootfstype=ext4 elevator=deadline rootwait

The cards picks up as follows:

pi@pi-roshnee-lm ~ $ dmesg

3.303196] usb 1-1.5: new full-speed USB device number 4 using dwc_otg
[    3.434770] usb 1-1.5: New USB device found, idVendor=0d8c, idProduct=013c
[    3.449598] usb 1-1.5: New USB device strings: Mfr=1, Product=2, SerialNumber=0
[    3.473047] usb 1-1.5: Product: USB PnP Sound Device
[    3.479635] usb 1-1.5: Manufacturer: C-Media Electronics Inc.      
[    3.513315] input: C-Media Electronics Inc.       USB PnP Sound Device as    /devices/platform/bcm2708_usb/usb1/1-1/1-1.5/1-1.5:1.3/input/input0
[    3.551191] hid-generic 0003:0D8C:013C.0001: input,hidraw0: USB HID v1.00 Device     [C-Media Electronics Inc.       USB PnP Sound Device] on usb-bcm2708_usb-1.5/input3
[    3.997860] udevd[156]: starting version 175
[    6.413474] bcm2708-i2s bcm2708-i2s.0: Failed to create debugfs directory
[    6.848620] usbcore: registered new interface driver snd-usb-audio

pi@pi-roshnee-lm ~ $cat /proc/asound/cards

 0 [Device         ]: USB-Audio - USB PnP Sound Device
                      C-Media Electronics Inc. USB PnP Sound Device at usb-  bcm2708_usb-1.5, full spee
 1 [ALSA           ]: bcm2835 - bcm2835 ALSA
                      bcm2835 ALSA

pi@pi-roshnee-lm ~ $lsusb

Bus 001 Device 002: ID 0424:9514 Standard Microsystems Corp. 
Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
Bus 001 Device 003: ID 0424:ec00 Standard Microsystems Corp. 
Bus 001 Device 004: ID 0d8c:013c C-Media Electronics, Inc. CM108 Audio Controller

pi@pi-roshnee-lm ~ $amixer

Simple mixer control 'Speaker',0
Capabilities: pvolume pswitch pswitch-joined penum
  Playback channels: Front Left - Front Right
  Limits: Playback 0 - 151
  Mono:
  Front Left: Playback 136 [90%] [-2.88dB] [on]
  Front Right: Playback 136 [90%] [-2.88dB] [on]
Simple mixer control 'Mic',0
  Capabilities: pvolume pvolume-joined cvolume cvolume-joined pswitch pswitch-joined   cswitch cswitch-joined penum
  Playback channels: Mono
  Capture channels: Mono
  Limits: Playback 0 - 127 Capture 0 - 16
  Mono: Playback 98 [77%] [18.37dB] [off] Capture 14 [88%] [20.83dB] [on]
 Simple mixer control 'Auto Gain Control',0
  Capabilities: pswitch pswitch-joined penum
  Playback channels: Mono
  Mono: Playback [on]

pi@pi-roshnee-lm ~ $ aplay -l

 **** List of PLAYBACK Hardware Devices ****
card 0: Device [USB PnP Sound Device], device 0: USB Audio [USB Audio]
  Subdevices: 1/1
   Subdevice #0: subdevice #0
 card 1: ALSA [bcm2835 ALSA], device 0: bcm2835 ALSA [bcm2835 ALSA]
  Subdevices: 8/8
  Subdevice #0: subdevice #0
  Subdevice #1: subdevice #1
  Subdevice #2: subdevice #2
  Subdevice #3: subdevice #3
  Subdevice #4: subdevice #4
  Subdevice #5: subdevice #5
  Subdevice #6: subdevice #6
  Subdevice #7: subdevice #7
 card 1: ALSA [bcm2835 ALSA], device 1: bcm2835 ALSA [bcm2835 IEC958/HDMI]
  Subdevices: 1/1
  Subdevice #0: subdevice #0

pi@pi-roshnee-lm ~ $ arecord -l

 **** List of CAPTURE Hardware Devices ****
 card 0: Device [USB PnP Sound Device], device 0: USB Audio [USB Audio]
  Subdevices: 1/1
  Subdevice #0: subdevice #0
  • are you using a powered mic? I tried a number of "PC" mics and found only by raising my voice at close range did I record any sound. – rob Oct 17 '14 at 7:47
  • I tried different mics, and used Auz from my phone where I played a track. Results were the same static humming noise, wiht nothing of what I was playing – Yusuf Oct 17 '14 at 8:02
  • @rob you were right....well almost. It turns out the mic I was using is damaged or something. – Yusuf Oct 17 '14 at 20:27
  • Check and see if this helps.. raspberrypi.stackexchange.com/a/50117/44327 -- it may be the mic, but perhaps not faulty, but just the wrong plug type. – R Porter Jun 21 '16 at 0:50
2

False alarm it would seem. The mic I was using was faulty. Therefore, my setup and config works when using AUX plugged in from a phone playing a track

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