Is there some trick to getting aplay audio output working?

Question

I have recorded a .wav file using the command:

arecord test.wav

But when I try to play it, there is no sound output. It's like the raspberry pi is stuck on mute. I initially thought that my microphone was defective, but I sent the wav file to my desktop and played it, and it definitely is not empty.

The audio on my raspberry pi works when I run the hello_audio.bin located in /opt/vc/src/hello_pi/hello_audio And it played a noise through my headphones, so I know it's not my headphones.

Answer 1

There are a few reasons why this could be happening.

Possible Problem #1: Wrong RasPi hardware audio output selected (auto vs. HDMI vs. headphone/pwm out)

Solution: Force selection of the correct hardware.

amixer cset numid=3 0 # automatic detection (not always reliable) 
amixer cset numid=3 1 # force headphone (PWM) output
amixer cset numid=3 2 # force HDMI output

I like to put these as aliases in my .bashrc file so I don't have to remember the commands:

alias use-audio-auto="amixer cset numid=3 0" # auto
alias use-audio-headphones="amixer cset numid=3 1" # headphones
alias use-audio-hdmi="amixer cset numid=3 2" # hdmi

---

Possible Problem #2: Misconfigured ALSA subsystem / misconfigured .asoundrc

Solution: Make sure ALSA is configured correctly with good defaults for the RasPi hardware. The /home/pi/.asoundrc file should contain:

pcm.mmap0 {
    type mmap_emul;
    slave {
      pcm "hw:0,0";
    }
}

pcm.!default {
   type hw;
   card 0;
}

ctl.!default {
   type hw;
   card 0;
}

---

Possible Problem #3: Wrong hardware output device chosen by aplay

Solution: Check what devices are available using aplay -l

Run aplay -l to list playback devices detected, you should see something like this that references bcm2835:

$ aplay -l
**** List of PLAYBACK Hardware Devices ****
card 0: 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 0: ALSA [bcm2835 ALSA], device 1: bcm2835 ALSA [bcm2835 IEC958/HDMI]
  Subdevices: 1/1
  Subdevice #0: subdevice #0

If you're trying to test the headphone out, you'd force usage of it with:

aplay -Dhw:0,0 test.wav # 'try playing test.wav using hardware card 0, subdevice 0 (headphones)

Then, if you'd like to change the default for your Raspberry Pi, adjust your .asoundrc file to use the right hardware card index #.

---

Possible Problem 4: Your sound is simply muted/too low and you need to turn it up.

Solution: Make sure alsa-utils is installed and run alsamixer

sudo apt-get install -y alsa-utils
alsamixer

Then use the F1-F6 keys and UI to push up the volume.

Use the arrow keys to jack up the volume and quit.

To save what you changed in alsamixer as defaults, do:

sudo alsactl store 0

---

Hope that helps! Peace.