Whether the video frame has reserved bytes ？

[yangfangfang1204]

whether the webcodecs has reserved byes in input encodedVideoChunk ?
decode: Input the crop information of one video frame and transparently transmit the crop information in output .
such as:
(1) input:
const chunk = new EncodedVideoChunk({ data, timestamp, type, reserve:8, // reserved bytes that we could transmit to output. })
decodeobj.decode(chunk);
(2) output
output(frame){
let timestamp = frame.timestamp;
let cropwidth = frame.reserver;
}

[padenot]

This is a duplicate of #189. There is no way to do this right now, but it's not the first time this has been asked for.