Baseline Widely available
The MediaRecorder()
constructor creates a new MediaRecorder
object that will record a specified MediaStream
.
The object can optionally be configured to record using a specific media container (file type), and, further, can specify the exact codec and codec configuration(s) to use by specifying the codecs
parameter.
new MediaRecorder(stream)
new MediaRecorder(stream, options)
Parameters
stream
The MediaStream
that will be recorded. This source media can come from a stream created using navigator.mediaDevices.getUserMedia()
or from an <audio>
, <video>
or <canvas>
element.
options
Optional
A dictionary object that can contain the following properties:
mimeType
Optional
A MIME type specifying the format for the resulting media; you may specify the container format (the browser will select its preferred codecs for audio and/or video), or you may use the codecs
parameter and/or the profiles
parameter to provide detailed information about which codecs to use and how to configure them. Applications can check in advance if a mimeType
is supported by the user agent by calling MediaRecorder.isTypeSupported()
. Defaults to an empty string.
audioBitsPerSecond
Optional
The chosen bitrate for the audio component of the media.
videoBitsPerSecond
Optional
The chosen bitrate for the video component of the media.
bitsPerSecond
Optional
The chosen bitrate for the audio and video components of the media. This can be specified instead of the above two properties. If this is specified along with one or the other of the above properties, this will be used for the one that isn't specified.
audioBitrateMode
Optional
The bitrate mode that should be used to encode the audio. Can be constant
, which indicates that the recorder should encode at a constant bitrate, or variable
, which indicates that the recorder should encode using a variable bitrate, thus allowing more space to be used for complex signals and less space for less-complex signals. Defaults to variable
.
videoKeyFrameIntervalDuration
Optional
The nominal interval in time between key frames in the encoded video stream. The user agent controls key-frame generation based on this option and the videoKeyFrameIntervalCount
option.
videoKeyFrameIntervalCount
Optional
The interval in number of frames between key frames in the encoded video stream. The user agent controls key-frame generation considering this option as well as videoKeyFrameIntervalDuration
option.
Note: If bits per second values are not specified for video and/or audio, the default adopted for video is 2.5Mbps, while the audio default is adaptive, depending upon the sample rate and the number of channels.
Note: Video resolution, frame rate and similar settings are specified as constraints when calling getUserMedia()
, not here in the MediaStream Recording API.
NotSupportedError
DOMException
Thrown if the specified MIME type is not supported by the user agent.
This example shows how to create a media recorder for a specified stream, whose audio bit rate is set to 128 Kbit/sec and whose video bit rate is set to 2.5 Mbit/sec. The recorded media data will be stored in an MP4 wrapper (so if you gather the chunks of media data and save them to disk, they will be in an MP4 file).
if (navigator.mediaDevices.getUserMedia) {
const constraints = { audio: true, video: true };
const chunks = [];
const onSuccess = (stream) => {
const options = {
audioBitsPerSecond: 128000,
videoBitsPerSecond: 2500000,
mimeType: "video/mp4",
};
const mediaRecorder = new MediaRecorder(stream, options);
m = mediaRecorder;
// â¦
};
}
Specifications Browser compatibility See also
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