The MediaStreamTrack.contentHint property is a string that hints at the type of content the track contains. Allowable values depend on the value of the MediaStreamTrack.kind property.

A string with one of the following values:

""

No contentHint has been set.

"speech"

The track should be treated as if it contains speech data. When setting this value, the value of MediaStreamTrack.kind must be "audio".

"speech-recognition"

The track should be treated as if it contains data for the purpose of speech recognition by a machine. When setting this value, the value of MediaStreamTrack.kind must be "audio".

"music"

The track should be treated as if it contains music. When setting this value, the value of MediaStreamTrack.kind must be "audio".

"motion"

The track should be treated as if it contains video where motion is important. For example, webcam video, movies or video games. When setting this value, the value of MediaStreamTrack.kind must be "video".

"detail"

The track should be treated as if video details are extra important. For example, presentations or web pages with text content, painting or line art. When setting this value, the value of MediaStreamTrack.kind must be "video".

"text"

The track should be treated as if video details are extra important, and that significant sharp edges and areas of consistent color can occur frequently. For example, presentations or web pages with text content. When setting this value, the value of MediaStreamTrack.kind must be "video".

This function takes a stream and a contentHint value, and applies the hint to each track. See the full example here, showing how different contentHint values change how the tracks display.

function setVideoTrackContentHints(stream, hint) {
  const tracks = stream.getVideoTracks();
  tracks.forEach((track) => {
    if ("contentHint" in track) {
      track.contentHint = hint;
      if (track.contentHint !== hint) {
        console.error(`Invalid video track contentHint: "${hint}"`);
      }
    } else {
      console.error("MediaStreamTrack contentHint attribute not supported");
    }
  });
}