MediaTrackSettings.sampleSize - Web APIs 编辑

The MediaTrackSettings dictionary's sampleSize property is an integer indicating the linear sample size (in bits per sample) the MediaStreamTrack is currently configured for. This lets you determine what value was selected to comply with your specified constraints for this property's value as described in the MediaTrackConstraints.sampleSize property you provided when calling either getUserMedia() or MediaStreamTrack.applyConstraints().

If needed, you can determine whether or not this constraint is supported by checking the value of MediaTrackSupportedConstraints.sampleSize as returned by a call to MediaDevices.getSupportedConstraints(). However, typically this is unnecessary since browsers will ignore any constraints they're unfamiliar with.

Syntax

var sampleSize = MediaTrackSettings.sampleSize;

Value

An integer value indicating how many bits each audio sample is represented by. The most commonly used sample size for many years now is 16 bits per sample, which was used for CD audio among others. Other common sample sizes are 8 (for reduced bandwidth requirements) and 24 (for high-resolution professional audio).

Each audio channel on the track requires sampleSize bits. That means that a given sample actually uses (sampleSize/8)*channelCount bytes of data. For example, 16-bit stereo audio requires (16/8)*2 or 4 bytes per sample.

Example

See Example: Constraint exerciser in Capabilities, constraints, and settings for an example.

Specifications

Browser compatibility

BCD tables only load in the browser

See also

• Media Capture and Streams API
• Capabilities, constraints, and settings
• MediaTrackConstraints.sampleSize
• MediaTrackSettings