The isTypeSupported() method of the MediaSource interface returns a Boolean value indicating if the given MIME type is supported by the current user agent — this is, if it can successfully create SourceBuffer objects for that MIME type.
The readyState read-only property of the MediaSource interface returns an enum representing the state of the current MediaSource. The three possible values are:
The removeSourceBuffer() method of the MediaSource interface removes the given SourceBuffer from the SourceBuffers list associated with this MediaSource object.
The sourceBuffers read-only property of the MediaSource interface returns a SourceBufferList object containing the list of SourceBuffer objects associated with this MediaSource.
A PromiseWorker is a ChromeWorker except instead of calling postMessage() to send a message, you call post(), which returns a Promise. JavaScript files imported into the worker scope and main thread scope which allows posting to the worker and receiving in the form of a promise. Like ChromeWorker objects, PromiseWorker is mostly used for js-ctypes but it is not limited to that. There is no XPCOM access, similar to ChromeWorker. This answers the question "When should I use a PromiseWorker?", and the answer is, whenever you would normally use a ChromeWorker, but want postMessage to return promises.
The appendWindowEnd property of the SourceBuffer interface controls the timestamp for the end of the append window, a timestamp range that can be used to filter what media data is appended to the SourceBuffer. Coded media frames with timestamps wthin this range will be appended, whereas those outside the range will be filtered out.
The appendWindowStart property of the SourceBuffer interface controls the timestamp for the start of the append window, a timestamp range that can be used to filter what media data is appended to the SourceBuffer. Coded media frames with timestamps wthin this range will be appended, whereas those outside the range will be filtered out.
The mode property of the SourceBuffer interface controls whether media segments can be appended to the SourceBuffer in any order, or in a strict sequence.
The timestampOffset property of the SourceBuffer interface controls the offset applied to timestamps inside media segments that are appended to the SourceBuffer.