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How-To: Audio Controls


Overview

Just Add Power supports with stereo output ports can distribute audio to an analog audio distribution system. The stereo output includes adjustable audio delay and volume control. Delay and volume can be adjusted through push-buttons on the bottom of the devices or through programming.

AVP Transmitters have two additional audio input ports - mic input and line input - for embedding additional analog audio sources onto the HDMI signal. Control of the three audio signals - HDMI, mic, line - allows each signal to be turned on and off independently.

ST1 Sound Transceivers are audio-only endpoints in a Just Add Power system that can act as either an audio input or an audio output. They can be part of 2G and 3G systems.


Download

Download the Audio Control manual for a portable copy of the information in this article. (Not yet updated to include the ST1 Sound Transceiver.)

The full justOS API (Bx.x.x) can be found at https://justaddpower.docs.stoplight.io/


Stereo Audio Delay

Models with a stereo output port have the ability to delay the analog audio signal to match with a digital video signal.

Audio Delay Commands

Audio delay ranges from 0 ms (milliseconds) to 175 ms. Default is 0 ms.

All commands are case-sensitive. Variables are represented by $X. A6.x.x commands will work on justOS firmwares as well. justOS commands will NOT work on A6.x.x firmware.

Firmware A6.x.x
Name Command Variable Options Example Description
Increase Delay AUD_DLY_SLOW $X 0 to 25 AUD_DLY_SLOW 4 Increase delay compared to current value by 7ms * value (28 in example)
Decrease Delay AUD_DLY_FAST $X 0 to 25 AUD_DLY_FAST 6 Decrease delay compared to current value by 7ms * value (42 in example)
Set Delay AUD_DLY_SET_VALUE $X 0 to 25 AUD_DLY_SLOW 12 Set delay to 7ms * value (84 in example)
Save Delay Value AUD_DLY_SAVE_VAL (none) AUD_DLY_SAVE_VAL Save the current delay value to persist through reboot
justOS Firmware Bx.x.x
Name Command Variable Options Example Description
Set Delay POST /command/audio/stereo/delay $X 0 to 175 POST /command/audio/stereo/delay 175 Set delay to the value (175ms in example)
Save Delay Value (none) (none) (none) Setting the delay automatically saves

Stereo Audio Volume

Models with a stereo output port can make minor adjustments to the volume level of the analog output.

Volume Commands

Volume adjustment ranges from -39dB to +6dB. Default is 0dB.

All commands are case-sensitive. Variables are represented by $X. A6.x.x commands will work on justOS firmwares as well. justOS commands will NOT work on A6.x.x firmware.

Firmware A6.x.x
Name Command Variable Options Example Description
Increase Volume vol_bth_up.sh (none) vol_bth_up.sh Increase volume compared to current value (1-31)
Decrease Volume vol_bth_dn.sh (none) vol_bth_dn.sh Decrease volume compared to current value (1-31)
Set Volume vol_bth_set.sh $X 1 (-39dB) to 31 (+6dB) in 1.5dB increments vol_bth_set.sh 31 Set volume to 31 (+6dB)
Mute Stereo Port vol_mute.sh (none) vol_mute.sh Mutes the stereo port. Persists until unmuted.
Unmute Stereo Port vol_unmute.sh (none) vol_unmute.sh Unmutes the stereo port. Volume returns to previous level.
justOS Firmwares Bx.x.x
Name Command Variable Options Example Description
Set Volume POST /command/audio/stereo/volume $X 0 (-39dB) to 11 (+6dB) in 5-6dB increments POST /command/audio/stereo/volume 10 Set volume. 10 is HDMI-level

Mic & Line Inputs

AVP Transmitters have two additional audio inputs: mic-input and line-input. The audio inputs are distributed over the network and are available to all Receivers watching that Transmitter.

Input Commands

HDMI, mic, and line audio inputs are enabled by default.

All commands are case-sensitive. Variables are represented by $X. A6.x.x commands will work on justOS firmwares as well. justOS commands will NOT work on A6.x.x firmware.

Firmware A6.x.x
Name Command Variable Options Example Description
Enable HDMI Audio dd_main_on.sh (none) dd_main_on.sh Enable audio transmission for HDMI input signal
Disable HDMI Audio dd_main_mute.sh (none) dd_main_mute.sh Disable audio transmission for HDMI input signal
Enable Line Audio dd_line_on.sh (none) dd_line_on.sh Enable the Line input port
Disable Line Audio dd_line_mute.sh (none) dd_line_mute.sh Disable the Line input port
Enable Mic Audio dd_mic_on.sh (none) dd_mic_on.sh Enable the Mic input port
Disable Mic Audio dd_mic_mute.sh (none) dd_mic_mute.sh Disable the Mic input port

The commands below for justOS only set the live status, and will not affect the on-boot status for the devices.

For the on-boot Settings commands, head to the 3G Device Settings article in the Audio section.

justOS Firmwares Bx.x.x
Name Command Variable Options Example Description
Enable/Disable HDMI Audio POST /command/audio/dsp/hdmi $X mute, on POST /command/audio/dsp/hdmi mute Set audio status for HDMI input signal (on or mute)
Enable/Disable Line Audio POST /command/audio/dsp/line $X mute, on POST /command/audio/dsp/line mute Set audio status for Line input port (on or mute)
Enable/Disable Mic Audio POST /command/audio/dsp/mic $X mute, on POST /command/audio/dsp/mic mute Set audio status for Mic input port (on or mute)

ST1 Transceiver

justOS Firmware

All commands are case-sensitive. Variables are represented by $X. justOS commands will NOT work on A6.x.x firmware.

Transmitter or Receiver Mode
Name Command Variable Options Example Description
Set Live Volume POST /command/audio/stereo/volume $X integer 0-11 POST /command/audio/stereo/volume 11 Set live volume level from 0-11.
Does not persist through reboot.
Read Live Volume GET /details/audio/stereo/volume (none) GET /command/audio/stereo/volume Check the current volume level setting
Set Boot-Up Volume POST /settings/audio/stereo/volume $X integer 0-11 POST /settings/audio/stereo/volume 11 Set the volume level when the unit boots up
Read Boot-Up Volume GET /settings/audio/stereo/volume (none) GET /settings/audio/stereo/volumel Check the volume level the unit will be set to when booting up

Hybrid Firmware

All commands are case-sensitive. Variables are represented by $X. A6.x.x commands will work on justOS firmwares as well.

Transmitter Mode
Name Command Variable Options Example Description
Set Live Volume echo $X > /sys/devices/platform/1500_i2s/analog_in_vol integer 0-100 echo 100 > /sys/devices/platform/1500_i2s/analog_in_vol Set live volume level from 0-100.
Does not persist through reboot.
Read Live Volume cat /sys/devices/platform/1500_i2s/analog_in_vol (none) cat /sys/devices/platform/1500_i2s/analog_in_vol Check the current volume level setting
Set Boot-Up Volume astparam s analog_in_val $X integer 0-100 astparam s analog_in_val 100 Set the volume level when the unit boots up
Read Boot-Up Volume astparam g analog_in_val (none) astparam g analog_in_val Check the volume level the unit will be set to when booting up
Receiver Mode
Name Command Variable Options Example Description
Set Live Volume echo $X > /sys/devices/platform/1500_i2s/analog_out_vol integer 0-100 echo 100 > /sys/devices/platform/1500_i2s/analog_out_vol Set live volume level from 0-100.
Does not persist through reboot.
Read Live Volume cat /sys/devices/platform/1500_i2s/analog_out_vol (none) cat /sys/devices/platform/1500_i2s/analog_out_vol Check the current volume level setting
Set Boot-Up Volume astparam s analog_out_val $X integer 0-100 astparam s analog_out_val 100 Set the volume level when the unit boots up
Read Boot-Up Volume astparam g analog_out_val (none) astparam g analog_out_val Check the volume level the unit will be set to when booting up
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  • 22-Dec-2020
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