ALSA

From Texas Instruments Embedded Processors Wiki

Contents 1 About 2 Utilities 3 Execution 4 Using amixer

About

ALSA - Advanced Linux Sound Architecture
ALSA utils contains the command line utilities for the ALSA project.

Visit alsa website for more information and to download source.

Utilities

• arecord
  • arecord application is used to record the audio coming from audio in line.
• aplay
  • aplay application is used to play the audio file on to the audio out line.
• amixer
  • amixer can control the audio (volume, etc)

Execution

• Command to record to a file.
  • arecord -f cd song.wav
• Command to playback from a file.
  • aplay -f cd song.wav
• command to loopback(record and playback)
  • arecord -f cd | aplay -f cd

The zip file- File:ALSA Scripts logs.zip contains script to test Audio using ALSA utils and logs of script run.

Using amixer

• Command to get the controls that can be modified.
  • amixer controls

Sample output of the above command is as follows:

# amixer controls
numid=1,iface=MIXER,name='PCM Playback Volume'
numid=2,iface=MIXER,name='Line DAC Playback Volume'
numid=5,iface=MIXER,name='LineL DAC Playback Volume'
numid=6,iface=MIXER,name='LineL Left PGA Bypass Playback Volume'
numid=8,iface=MIXER,name='LineL Line2 Bypass Playback Volume'
numid=3,iface=MIXER,name='LineL Playback Switch'
numid=9,iface=MIXER,name='LineR Line2 Bypass Playback Volume'
numid=4,iface=MIXER,name='LineR Playback Switch'
numid=7,iface=MIXER,name='LineR Right PGA Bypass Playback Volume'
numid=11,iface=MIXER,name='Mono DAC Playback Switch'
numid=10,iface=MIXER,name='Mono DAC Playback Volume'
[. . . ]
[. . . ]

• Command to get the control contents
  • amixer cget numid=X

Example:

# amixer cget numid=1
numid=1,iface=MIXER,name='PCM Playback Volume'
  ; type=INTEGER,access=rw---R--,values=2,min=0,max=127,step=0
  : values=96,96
  | dBscale-min=-63.50dB,step=0.50dB,mute=0

• Command to set the control contents
  • amixer cset numid=X <Val>

Example:

# amixer cset numid=1 110
numid=1,iface=MIXER,name='PCM Playback Volume'
  ; type=INTEGER,access=rw---R--,values=2,min=0,max=127,step=0
  : values=110,110
  | dBscale-min=-63.50dB,step=0.50dB,mute=0

On DM644x and DM355 EVMs, use the interface No.1 (Name = "PCM Playback Volume") to control the Output Volume and interface No.26 (Name = "PGA Capture Volume") to control the Capture Volume.

• Command to set Line-In as capture source on DM6467 and DM365 EVMs

# amixer cset numid=56 on   # Right Line1R ON
# amixer cset numid=57 off  # Right Line1L OFF
# amixer cset numid=64 on   # Left Line1L ON
# amixer cset numid=65 off  # Left Line1R OFF
# amixer cset numid=59 off  # Right Mic3L  OFF
# amixer cset numid=60 off  # Right Mic3R  OFF
# amixer cset numid=67 off  # Left Mic3L  OFF
# amixer cset numid=68 off  # Left Mic3R  OFF

• Command to set Mic-In as capture source on DM6467 and DM365 EVMs

# amixer cset numid=56 off  # Right Line1R OFF
# amixer cset numid=57 off  # Right Line1L OFF
# amixer cset numid=64 off  # Left Line1L OFF
# amixer cset numid=65 off  # Left Line1R OFF
# amixer cset numid=59 off  # Right Mic3L  OFF
# amixer cset numid=60 on   # Right Mic3R  ON
# amixer cset numid=67 on   # Left Mic3L  ON
# amixer cset numid=68 off  # Left Mic3R  OFF

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