Audio

Audio

An audio signal is a representation of sound, typically as an electrical voltage. Audio signals have frequencies in the audio frequency range of roughly 20 to 20,000 Hz (the limits of human hearing). wikipedia

Required Hardware

USB Audio Dongle USB PnP Sound Device

Kernel Integration

Advanced Linux Sound Architecture

The Advanced Linux Sound Architecture (ALSA) provides audio and MIDI functionality to the Linux operating system.

Kernel Display Message

root@edison:~# dmesg
...
[ 3750.683557] hub 1-0:1.0: USB hub found
[ 3750.683602] hub 1-0:1.0: 1 port detected
[ 3750.684174] dwc3-host dwc3-host.2: xHCI Host Controller
[ 3750.684573] dwc3-host dwc3-host.2: new USB bus registered, assigned bus number 2
[ 3750.684764] usb usb2: New USB device found, idVendor=1d6b, idProduct=0003
[ 3750.684789] usb usb2: New USB device strings: Mfr=3, Product=2, SerialNumber=1
[ 3750.684809] usb usb2: Product: xHCI Host Controller
[ 3750.684829] usb usb2: Manufacturer: Linux 3.10.98-poky-edison+ dwc-xhci
[ 3750.684848] usb usb2: SerialNumber: dwc3-host.2
[ 3750.688503] xHCI xhci_add_endpoint called for root hub
[ 3750.688527] xHCI xhci_check_bandwidth called for root hub
[ 3750.688852] hub 2-0:1.0: USB hub found
[ 3750.688899] hub 2-0:1.0: 1 port detected
[ 3750.749302] pmic_ccsm pmic_ccsm: USB VBUS Detected. Notifying OTG driver
[ 3751.001112] usb 1-1: new full-speed USB device number 2 using dwc3-host
[ 3751.023554] usb 1-1: New USB device found, idVendor=0d8c, idProduct=013c
[ 3751.023585] usb 1-1: New USB device strings: Mfr=1, Product=2, SerialNumber=0
[ 3751.023607] usb 1-1: Product: USB PnP Sound Device
[ 3751.055963] input: USB PnP Sound Device as /devices/pci0000:00/0000:00:11.0/dwc3-host.2/usb1/1-1/1-1:1.3/input/input7
[ 3751.056818] hid-generic 0003:0D8C:013C.0005: input,hidraw0: USB HID v1.00 Device [USB PnP Sound Device] on usb-dwc3-host.2-1/input3

USB Devices

root@edison:~# lsusb
Bus 002 Device 001: ID 1d6b:0003 Linux Foundation 3.0 root hub
Bus 001 Device 002: ID 0d8c:013c C-Media Electronics, Inc. CM108 Audio Controller
Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub

Userspace Interfaces

ProcFs

root@edison:~# cat /proc/asound/cards
 0 [Loopback       ]: Loopback - Loopback
                      Loopback 1
 1 [dummyaudio     ]: dummy-audio - dummy-audio
                      dummy-audio
 2 [Device         ]: USB-Audio - USB PnP Sound Device
                      USB PnP Sound Device at usb-dwc3-host.2-1, full speed
root@edison:~#

Applications / Libraries

Setup

Opkg

root@edison:~# opkg install alsa-utils espeak
...
Configuring libsamplerate0.
Configuring libjack.
Configuring alsa-utils-alsaloop.
Configuring alsa-utils-alsaucm.
Configuring alsa-utils-midi.
Configuring alsa-utils-iecset.
Configuring alsa-utils-aconnect.
Configuring libportaudio2.
Configuring espeak.
Configuring alsa-utils-speakertest.
Configuring alsa-utils-aseqnet.
Configuring alsa-utils-aseqdump.
Configuring alsa-utils.
Configuring mpg123.
...
root@edison:~# opkg install --nodeps jack-dev 
Installing jack-dev (0.121.0-r0) on root.
Downloading http://repo.opkg.net/edison/repo/core2-32/jack-dev_0.121.0-r0_core2-32.ipk.
Configuring jack-dev.
root@edison:~# opkg install --nodeps libportaudio-dev
Installing libportaudio-dev (v19+svnr1387-r0) on root.
Downloading http://repo.opkg.net/edison/repo/core2-32/libportaudio-dev_v19+svnr1387-r0_core2-32.ipk.
Configuring libportaudio-dev.
root@edison:~#

Apt-Get

    root@edison:~# apt-get install alsa-utils mpg123 espeak

Free Sound Effects

Programs

Audio Files

    root@edison:~# ls /usr/share/sounds/alsa/
    Front_Center.wav  Noise.wav         Rear_Right.wav
    Front_Left.wav    Rear_Center.wav   Side_Left.wav
    Front_Right.wav   Rear_Left.wav     Side_Right.wav

List Capture Hardware Devices

root@edison:~# arecord -l
**** List of CAPTURE Hardware Devices ****
card 0: Loopback [Loopback], device 0: Loopback PCM [Loopback PCM]
  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: Loopback [Loopback], device 1: Loopback PCM [Loopback PCM]
  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: dummyaudio [dummy-audio], device 0: 14 []
  Subdevices: 1/1
  Subdevice #0: subdevice #0
card 1: dummyaudio [dummy-audio], device 1: ((null)) []
  Subdevices: 1/1
  Subdevice #0: subdevice #0
card 1: dummyaudio [dummy-audio], device 2: ((null)) []
  Subdevices: 1/1
  Subdevice #0: subdevice #0
card 2: Device [USB PnP Sound Device], device 0: USB Audio [USB Audio]
  Subdevices: 1/1
  Subdevice #0: subdevice #0
root@edison:~#

List Playback Hardware Devices

root@edison:~# aplay -l
**** List of PLAYBACK Hardware Devices ****
card 0: Loopback [Loopback], device 0: Loopback PCM [Loopback PCM]
  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: Loopback [Loopback], device 1: Loopback PCM [Loopback PCM]
  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: dummyaudio [dummy-audio], device 0: 14 []
  Subdevices: 1/1
  Subdevice #0: subdevice #0
card 1: dummyaudio [dummy-audio], device 1: ((null)) []
  Subdevices: 1/1
  Subdevice #0: subdevice #0
card 1: dummyaudio [dummy-audio], device 2: ((null)) []
  Subdevices: 1/1
  Subdevice #0: subdevice #0
card 2: Device [USB PnP Sound Device], device 0: USB Audio [USB Audio]
  Subdevices: 1/1
  Subdevice #0: subdevice #0

Arecord / Aplay

root@edison:~# arecord -f cd -D plughw:2,0 -d 20 test.wav # USB
Recording WAVE 'test.wav' : Signed 16 bit Little Endian, Rate 44100 Hz, Stereo
^CAborted by signal Interrupt...
root@edison:~# aplay -D hw:2,0 test.wav # USB
Playing WAVE 'test.wav' : Signed 16 bit Little Endian, Rate 44100 Hz, Stereo

Device Configuration

root@edison:~# vi ~/.asoundrc
pcm.!default {
    type plug
       slave {
           pcm "hw:2,0"
       }
}
ctl.!default {
    type plug
        slave {
           pcm "hw:2,0"
       }
}
root@edison:~# arecord -f cd -d 20 test.wav
Recording WAVE 'test.wav' : Signed 16 bit Little Endian, Rate 44100 Hz, Stereo
^CAborted by signal Interrupt...
root@edison:~# aplay test.wav
Playing WAVE 'test.wav' : Signed 16 bit Little Endian, Rate 44100 Hz, Stereo

Other Configuration

pcm.!default {
        type asym
        playback.pcm {
                type plug
                slave.pcm "hw:2,0"
        }
        capture.pcm {
                type plug
                slave.pcm "hw:3,0"
        }
}

ctl.!default {
    type plug
        slave {
           pcm "hw:2,0"
       }
}

Other Configuration

pcm.!default {
        type asym
        playback.pcm {
                type plug
                slave.pcm "hw:2,0"
        }
        capture.pcm {
                type plug
                slave.pcm "hw:2,0"
        } 
}

Other Configuration

    root@edison:~# vi /etc/asound.conf
    pcm.!default sysdefault:Device
    root@edison:~# aplay -Ll
    root@edison:~# vi ~/.asoundrc
    root@edison:~# vi /etc/asound.conf
    pcm.!default sysdefault:Device
    root@edison:~# aplay /usr/share/sounds/alsa/Front_Center.wav
    root@edison:~# aplay -D hw:1,0 /usr/share/sounds/alsa/Front_Center.wav

Play Wav Sample File

root@edison:~# aplay /usr/share/sounds/alsa/Front_Center.wav                                        Playing WAVE '/usr/share/sounds/alsa/Front_Center.wav' : Signed 16 bit Little Endian, Rate 48000 Hz, Mo
root@edison:~# aplay /usr/share/sounds/alsa/Rear_Center.wav 
Playing WAVE '/usr/share/sounds/alsa/Rear_Center.wav' : Signed 16 bit Little Endian, Rate 48000 Hz, Moo
root@edison:~#

Speaker-Test

root@edison:~# speaker-test 
speaker-test 1.0.28
Playback device is default
Stream parameters are 48000Hz, S16_LE, 1 channels
Using 16 octaves of pink noise
...
...
^C
root@edison:~#

Mpg123

root@edison:~# mpg123

Espeak

root@edison:~# espeak
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