https://developer.mozilla.org/en-US/docs/Web/API/BlobEvent/timecode
BlobEvent: timecode property - Web APIs | MDN
The timecode read-only property of the BlobEvent interface indicates the difference between the timestamp of the first chunk of data, and the timestamp of the...
web apistimecodepropertymdn
https://developer.mozilla.org/en-US/docs/Web/API/BlobEvent/data
BlobEvent: data property - Web APIs | MDN
The data read-only property of the BlobEvent interface represents a Blob associated with the event.
data propertyweb apismdn