Defold-Mic (Microphone input extension)

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Defold-Mic

A Defold extension for microphone recording via miniaudio.

Compatibility

This extension works without any restrictions on the following platforms:

Android

For using the microphone on Android devices, you have to first get the permission android.permission.RECORD_AUDIO from the user, for example using extension-permissions.

macOS

On macOS, you have to first get the permission to use the microphone, for example using mic.request_permission().

Currently the extension does not seem to work on debug builds from the Defold editor, but only in release bundles. This is likely because Defold is missing NSMicrophoneUsageDescription in its manifest. So for debugging on macOS, you need to use a release bundle, or a HTML5 build.

iOS

This extension has not been tested on iOS yet. It should work with mic.request_permission(). If you use it on iOS, please tell me the results, positive or negaive.

Usage

mic.start([options])

Begin audio capture. Accepts an optional Lua table with capture settings.

Key Type Description
device_index number Zero-based index of the capture device to use, as returned by mic.get_devices(). Defaults to the system default device.
sample_rate number Sample rate in Hz. Usually 16000, 22050, 44100, or 48000. Defaults to 16000.
channels number Number of audio channels. Must be 1 (mono) or 2 (stereo). Defaults to 1.
max_seconds number Maximum number of seconds to buffer. Once reached, incoming audio is discarded. 0 means unlimited. Defaults to 60 seconds.
noise_gate_threshold number Amplitude threshold in range [0.0, 1.0]. Frames whose peak amplitude falls below are silenced. Defaults to 0. 
mic.start()

mic.start({
    sample_rate = 16000,
    channels = 1,
    max_seconds = 10,
    noise_gate_threshold = 0.02,
})

mic.stop([options])

Stop audio capture and return the recorded audio as a WAV byte string. Optional table options, with only possible key normalize_peak to normalize recorded audio to, in (0.0, 1.0]. Returns nil if nothing was recorded.

mic.start()
-- ...
local wav = mic.stop()
if wav then
    local path = go.get("#voice", "sound")
    resource.set_sound(path, wav)
end

local wav = mic.stop({normalize_peak = 0.8})
local f = io.open("recording.wav", "wb")
if f then
    f:write(wav)
    f:close()
end

mic.is_recording()

Check whether the microphone is currently capturing audio. Returns true if recording, false otherwise.

if mic.is_recording() then
    print("Currently recording.")
end

mic.is_connected()

Check whether at least one capture device is available on the system. Returns true if one or more capture devices are available, false otherwise.

if not mic.is_connected() then
    print("No microphone found!")
end

mic.get_devices()

Enumerate all available capture devices. Returns a list of device info tables, each with keys index and name. (On HTML5, there will likely only be the microphone selected by the user for their browser.)

local devices = mic.get_devices()
pprint(devices)

mic.start({ device_index = devices[2].index })

mic.get_current_device()

Returns the name of the current capture device.

local device = mic.get_current_device()

mic.get_peak()

Get the peak amplitude of the current block. Returns a normalised value in the range [0.0, 1.0], or 0.0 if not recording.

mic.start()

function update(self, dt)
    print("Peak amplitude:", mic.get_peak())
end

mic.get_rms()

Get the RMS (root mean square) volume of the current block. Returns a normalised value in the range [0.0, 1.0], or 0.0 if not recording.

mic.start()

function update(self, dt)
    if mic.get_rms() > 0.1 then
        print("Somebody is speaking!")
    end
end

mic.get_duration()

Get the duration of audio buffered so far in the current recording. Returns duration in seconds, or 0.0 if not recording.

mic.start({ max_seconds = 30 })

function update(self, dt)
    print("Time left to record:", 30 - mic.get_duration())
end

mic.request_permission()

Request permission to use the microphone. (macOS and iOS only)

mic.request_permission()

mic.get_permission_status()

Get the current status of the permission to use the microphone. (macOS and iOS only)

APPLE_MIC_PERMISSION_UNAVAILABLE    = -1,
APPLE_MIC_PERMISSION_NOT_DETERMINED = 0,
APPLE_MIC_PERMISSION_RESTRICTED     = 1,
APPLE_MIC_PERMISSION_DENIED         = 2,
APPLE_MIC_PERMISSION_GRANTED        = 3,

local status = mic.get_permission_status()

Contributions

Thanks to subsoap for implementing the permissions for macOS!

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