Recorder.js

A library for recording/exporting the output of Web Audio API nodes. This is a version which supports encoding the audio using libopus ver 1.1.1 beta compiled with emscripten.

Syntax

Constructor

var rec = new Recorder([config]);

Creates a recorder instance. Instantiating an instance will prompt the user for permission to access the audio input stream.

config - An optional configuration object (see config section below)

Config

bitDepth - (optional) Specifies the bitdepth to record at. Defaults to 16. Supported values are 8, 16, 24, 32. If recordOpus is true, this value will be forced to 16.
bufferLength - (optional) The length of the buffer that the internal JavaScriptNode uses to capture the audio. Can be tweaked if experiencing performance issues. Defaults to 4096.
monitorGain - (optional) Sets the gain of the monitoring output. Gain is an a-weighted value between 0 and 1. Defaults to 0
numberOfChannels - (optional) The number of channels to record. 1 = mono, 2 = stereo. Defaults to 1. More than two channels has not been tested.
recordOpus - (optional) Specifies if recorder should record using the opus encoder. Defaults to true. Additionaly, an optional opus configurations can be specified as an object here.
sampleRate - (optional) Specifies the sample rate to record at. Defaults to device sample rate. If different than native rate, the audio will be filtered and resampled. If recordOpus is true, this value will default to 48000. The Opus encoder will not work if the value is not 8000, 12000, 16000, 24000 or 48000.
workerPath - (optional) Path to recorder.js worker script. Defaults to 'recorderWorker.js'

Opus Config

stream - (optional) Specifies wheather dataAvailable event should be fired when each page is ready. If true, requestData will have no effect. Defaults to false.
maxBuffersPerPage - (optional) Specifies the maximum number of buffers to use before generating an Ogg page. This can be used to lower the streaming latency. The lower the value the more overhead the ogg stream will incur. Defaults to 40.
encoderApplication - (optional) Specifies the encoder application. Supported values are 2048 - Voice, 2049 - Full Band Audio, 2051 - Restricted Low Delay. Defaults to 2049.
encoderFrameSize (optional) Specifies the frame size in ms used for encoding. Defaults to 20.

Instance Methods

rec.addEventListener( type, listener[, useCapture] )

addEventListener will add an event listener to the event target. Available events are "recordingProgress", "streamError", "streamReady", dataAvailable", "start", "pause", "resume" and "stop".

rec.setMonitorGain( gain )

setMonitorGain will set the volume on what will be passed to the monitor. Monitor level does not affect the recording volume. Gain is an a-weighted value between 0 and 1

rec.pause()

pause will keep the stream and monitoring alive, but will not be recording the buffers. Will raise the pause event. Subsequent calls to resume will add to the current recording.

rec.removeEventListener( type, listener[, useCapture] )

removeEventListener will remove an event listener from the event target.

rec.requestData()

requestData will request the recorded data if not recording. If successful, the event "dataAvailable" will be published with a blob containing the appropriate data as an ogg or wav file depending on config. requestData will not work if recordOpus stream is enabled, as the data is being streamed and not recorded.

rec.resume()

resume will resume the recording if paused. Will raise the resume event

rec.start()

start will initalize the worker and the audio stream and begin capturing audio when ready. Will raise the start event when started.

rec.stop()

stop will cease capturing audio and disable the monitoring and mic input stream. Will request the recorded data and then terminate the worker once the final data has been published. Will raise the stop event when stopped.

Static Methods

Recorder.isRecordingSupported()

Will return a boolean value indicating if the browser supports recording.

Recorder.js License (MIT)

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

Opus License (BSD)

Redistribution and use in source and binary forms, with or without modification, are permitted provided that the following conditions are met:

Redistributions of source code must retain the above copyright notice, this list of conditions and the following disclaimer.
Redistributions in binary form must reproduce the above copyright notice, this list of conditions and the following disclaimer in the documentation and/or other materials provided with the distribution.
Neither the name of Internet Society, IETF or IETF Trust, nor the names of specific contributors, may be used to endorse or promote products derived from this software without specific prior written permission.

THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

Opus is subject to the royalty-free patent licenses which are specified at:

Xiph.Org Foundation: https://datatracker.ietf.org/ipr/1524/

Microsoft Corporation: https://datatracker.ietf.org/ipr/1914/

Broadcom Corporation: https://datatracker.ietf.org/ipr/1526/

lepinsk/Recorderjs