Signal Generator tool

This directory contains a developer tool that generates and outputs audio signals, via the Audio, AudioCore, AudioRenderer, VolumeControl and GainControl FIDL protocols.

USAGE

signal_generator
  [--chans=<NUM_CHANS>]
  [--int16 | --int24]
  [--rate=<FRAME_RATE>]
  [--usage=<RENDER_USAGE>]
  [--sine[=<FREQ>] | --square[=<FREQ>] | --saw[=<FREQ>] | --noise]
  [--dur=<DURATION_SEC>]
  [--amp=<AMPL>]
  [--wav[=<FILEPATH>]]
  [--frames=<PACKET_SIZE>]
  [--num-bufs=<NUM_BUFFERS>]
  [--pts]
  [--threshold=<SECS>]
  [--gain[=<STREAM_GAIN_DB>]]
  [--mute[=<0|1>]]
  [--ramp]
  [--end-gain=<TARGET_GAIN_DB>]
  [--ramp-dur=<RAMP_DURATION_MSEC>]
  [--usage-gain[=<GAIN_DB>]]
  [--usage-vol[=<VOLUME>]]
  [--help | --?]

These optional parameters are interpreted as follows:

  By default, set stream format to 2-channel float32 at 48000 Hz with a MEDIA usage
--chans=<NUM_CHANS>      Specify number of channels
--int16                  Use 16-bit integer samples
--int24                  Use 24-in-32-bit integer samples (left-justified 'padded-24')
--rate=<FRAME_RATE>      Set frame rate in Hz
--usage=<RENDER_USAGE>   Set stream render usage. RENDER_USAGE must be one of:
                         BACKGROUND, MEDIA, INTERRUPTION, SYSTEM_AGENT, COMMUNICATION

  By default, signal is a 440.0 Hz sine wave
--sine[=<FREQ>]          Play sine wave at given frequency (Hz)
--square[=<FREQ>]        Play square wave at given frequency
--saw[=<FREQ>]           Play rising sawtooth wave at given frequency
--noise                  Play pseudo-random 'white' noise
  If no frequency is provided (e.g. '--square'), 440.0 Hz is used

  By default, signal plays for 2.0 seconds, at amplitude 0.25
--dur=<DURATION_SECS>    Set playback length in seconds
--amp=<AMPL>             Set amplitude (full-scale=1.0, silence=0.0)

--wav[=<FILEPATH>]       Save to .wav file ('/tmp/signal_generator.wav' if only '--wav' is
                         provided)

  Subsequent settings (e.g. gain, timestamps) do not affect .wav file contents

  By default, submit data in non-timestamped buffers of 480 frames and 1 VMOs.
--frames=<FRAMES>        Set data buffer size in frames 
--num-bufs=<NUM_BUFFERS> Set the number of payload buffers to use 
--pts                    Apply presentation timestamps (units: frames)
--threshold[=<SECS>]     Set PTS discontinuity threshold, in seconds (0.0, if unspecified)

  By default, AudioRenderer gain and mute are not set (unity 0.0 dB unmuted, no ramping)
--gain[=<GAIN_DB>]       Set stream gain (dB in [-160.0, 24.0]; 0.0 if only '--gain' is
                         provided)
--mute[=<0|1>]           Set stream mute (0=Unmute or 1=Mute; Mute if only '--mute' is
                         provided)
--ramp                   Smoothly ramp gain from initial value to a target -75.0 dB by
                         end-of-signal. If '--gain' is not provided, ramping starts at unity
                         stream gain (0.0 dB)
--end-gain=<GAIN_DB>     Set a different ramp target gain (dB). Implies '--ramp'
--ramp-dur=<DURATION_MS> Set a specific ramp duration in milliseconds. Implies '--ramp'

  By default, both volume and gain for this RENDER_USAGE are unchanged
--usage-gain[=<GAIN_DB>] Set render usage gain (dB in [-160.0, 0.0]; 0.0 if only '--usage-gain'
                         is provided)
--usage-vol[=<VOLUME>]   Set render usage volume ([0.0, 1.0]; 0.50 if only '--usage-vol' is
                         provided)

--help, --?              Show this message

IMPORTANT NOTE

Developers can use this tool to change systemwide render-usage volume and gain. These changes persist beyond this tool's invocation.