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audio-driver-ctl

Play, record, and configure audio streams.

Usage

audio-driver-ctl [-d <id>] [-t (input|output)] agc (on|off)

audio-driver-ctl [-a <mask>] [-b (8|16|20|24|32)] [-c <channels>] \
    [-d <id>] [-r <hertz>] duplex <playpath> <recordpath>

audio-driver-ctl [-d <id>] [-t (input|output)] gain <decibels>

audio-driver-ctl [-d <id>] [-t (input|output)] info

audio-driver-ctl [-a <mask>] [-b (8|16|20|24|32)] [-c <channels>] \
    [-d <id>] loop <playpath>

audio-driver-ctl [-d <id>] [-t (input|output)] mute

audio-driver-ctl [-a <mask>] [-b (8|16|20|24|32)] [-c <channels>] \
    [-d <id>] [-r <hertz>] noise [<seconds>] [<amplitude>]

audio-driver-ctl [-a <mask>] [-b (8|16|20|24|32)] [-c <channels>] \
    [-d <id>] play <playpath>

audio-driver-ctl [-d <id>] [-t (input|output)] pmon [<seconds>]

audio-driver-ctl [-a <mask>] [-b (8|16|20|24|32)] [-c <channels>] \
    [-d <id>] [-r <hertz>] record <recordpath> [<seconds>]

audio-driver-ctl [-a <mask>] [-b (8|16|20|24|32)] [-c <channels>] \
    [-d <id>] [-r <hertz>] tone [<frequency>] [<seconds>] [<amplitude>

audio-driver-ctl [-d <id>] [-t (input|output)] unmute

Options

-a <mask>

Active channel mask. For example 0xf or 15 for channels 0, 1, 2, and 3. Defaults to all channels.

-b (8|16|20|24|32)

Bits per sample. Defaults to 16.

-c <channels>

Number of channels to use when recording or generating tones/noises. Does not affect WAV file playback because WAV files specify how many channels to use in their headers. Defaults to the first driver-reported value. Run info to see how many channels your target Fuchsia device has. The number of channels must match what the audio driver expects because audio-driver-ctl does not do any mixing.

-d <id>

The device node ID of the stream. Defaults to 0. To figure out <id> run info. You'll see a path value like /dev/class/audio-input/000. <id> in this example is 000.

-t (input|output)

The device type. Defaults to output. This option is ignored for commands like play that only make sense for one of the types.

-r <hertz>

The frame rate in hertz. Defaults to 48000.

Commands

agc

audio-driver-ctl [-d <id>] [-t (input|output)] agc (on|off)

Enables or disables automatic gain control for the stream.

duplex

audio-driver-ctl [-a <mask>] [-b (8|16|20|24|32)] [-c <channels>] \
    [-d <id>] [-r <hertz>] duplex <playpath> <recordpath>

Simultaneously plays the WAV file located at <playpath> and records another WAV file into <recordpath> in order to analyze the delays in the system. The -c option if provided applies to the recording side since the number of channels for playback is taken from the WAV file header.

gain

audio-driver-ctl [-d <id>] [-t (input|output)] gain <decibels>

Sets the gain of the stream in decibels.

info

audio-driver-ctl [-d <id>] [-t (input|output)] info

Gets capability and status info for a stream.

loop

audio-driver-ctl [-a <mask>] [-b (8|16|20|24|32)] [-c <channels>] \
    [-d <id>] loop <playpath>

Repeatedly plays the WAV file at <playpath> on the selected output until a key is pressed.

mute

audio-driver-ctl [-d <id>] [-t (input|output)] mute

Mutes a stream.

noise

audio-driver-ctl [-a <mask>] [-b (8|16|20|24|32)] [-c <channels>] \
    [-d <id>] [-r <hertz>] noise [<seconds>] [<amplitude>]

Plays pseudo-white noise. <seconds> controls how long the noise plays and must be at least 0.001 seconds. If <seconds> is not provided the noise plays until a key is pressed.

play

audio-driver-ctl [-a <mask>] [-b (8|16|20|24|32)] [-c <channels>] \
    [-d <id>] play <playpath>

Plays a WAV file.

pmon

audio-driver-ctl [-d <id>] [-t (input|output)] pmon [<seconds>]

Monitors the plug state of a stream. <seconds> must be above 0.5 seconds (default: 10.0 seconds).

record

audio-driver-ctl [-a <mask>] [-b (8|16|20|24|32)] [-c <channels>] \
    [-d <id>] [-r <hertz>] record <recordpath> [<seconds>]

Records to the specified WAV file from the selected input. If <seconds> is not provided the input is recorded until a key is pressed.

tone

audio-driver-ctl [-a <mask>] [-b (8|16|20|24|32)] [-c <channels>] \
    [-d <id>] [-r <hertz>] tone [<frequency>] [<seconds>] [<amplitude>

Plays a sinusoidal tone. <frequency> must be between 15.0 and 96000.0 hertz (default: 440.0 hertz). <seconds> must be above 0.001 seconds. If is not provided the tone plays until a key is pressed. <amplitude> scales the output if provided and must be an increment of 0.1 between 0.1 and 1.0.

unmute

audio-driver-ctl [-d <id>] [-t (input|output)] unmute

Unmutes a stream. Note that the gain of the stream will be reset to its default value.

Examples

Enable automatic gain control on a stream

$ audio-driver-ctl agc on

Get stream info

# Equivalent to `audio-driver-ctl -t output -d 000 info`
$ audio-driver-ctl info
Info for audio output at \"/dev/class/audio-output/000\"
  Unique ID    : 0100000000000000-0000000000000000
  Manufacturer : Spacely Sprockets
  Product      : acme
  Current Gain : 0.00 dB (unmuted, AGC on)
  Gain Caps    : gain range [-103.00, 24.00] in 0.50 dB steps; can mute; can AGC
  Plug State   : plugged
  Plug Time    : 12297829382473034410
  PD Caps      : hardwired
Number of channels      : 1
Frame rate              : 8000Hz
Bits per channel        : 16
Valid bits per channel  : 16
...

Set gain of a stream to -40 decibels

# Equivalent to `audio-driver-ctl -t output -d 000 gain -40`
$ audio-driver-ctl gain -40

Mute a stream

# Equivalent to `audio-driver-ctl -t output -d 000 mute`
$ audio-driver-ctl mute

Repeatedly play (loop) a WAV file on a stream

# Equivalent to `audio-driver-ctl -t output -d 000 loop /tmp/test.wav`
$ audio-driver-ctl loop /tmp/test.wav
Looping /tmp/test.wav until a key is pressed

Play a WAV file once on a stream

# Equivalent to `audio-driver-ctl -t output -d 000 play /tmp/test.wav`
$ audio-driver-ctl play /tmp/test.wav

Play a 450 hertz tone for 1 second at 50% amplitude on a stream

# Equivalent to `audio-driver-ctl -t output -d 000 tone 450 1 0.5`
$ audio-driver-ctl tone 450 1 0.5
Playing 450.00 Hz tone for 1.00 seconds at 0.50 amplitude

Unmute a stream

# Equivalent to `audio-driver-ctl -t output -d 000 unmute`
audio-driver-ctl unmute

Notes

Accessing this command

This command is only available on certain diagnostic and testing Fuchsia builds.

This is a device-side command, not a host-side command like fx or ffx. In other words before calling this command you must first access the shell of the Fuchsia device.

To interactively access the Fuchsia device's shell:

ffx component explore <component>

Replace <component> with the name of the component that has access to the command documented on this page.

To call a single command and return the output to the host:

ffx component explore <component> -c "<command>"

Replace <command> with one of the commands documented on this page.

Supported builds for commands that exercise streams

Commands that exercise audio streams such as play are only supported in diagnostic product bundles like core. In other builds only the informational commands like info are supported.

Copying WAV files between a host and a target Fuchsia device

To copy WAV files from your host to your target Fuchsia device or vice versa, run fx cp (--to-target|--to-host) <source> <destination> on your host. <source> is the file you want to copy and <destination> is where you want to put the copied file.

Example of copying from host to target Fuchsia device:

$ fx cp --to-target /path/on/host/source.wav /path/on/target/destination.wav

Example of copying from target Fuchsia device to host:

$ fx cp --to-host /path/on/target/source.wav /path/on/host/destination.wav

Both commands should be run from your host, not the target Fuchsia device.

Source code

Source code for audio-driver-ctl: //src/media/audio/tools/audio-driver-ctl/