Support for DASHEventMessageBox Version 1

Created by: damienlevin

The latest 2.9.0 version doesn't seems to support DASHEventMessageBox version 1 (version 0 is supported)

See: https://github.com/Dash-Industry-Forum/dash.js/blob/36baa49b658bf385384f39e7e621cd596644f70b/src/streaming/vo/IsoBox.js#L66

Format is:

aligned(8) class DASHEventMessageBox extends FullBox(‘emsg’, version, flags = 0){
if (version==0) {
string scheme_id_uri;
string value;
unsigned int(32) timescale;
unsigned int(32) presentation_time_delta;
unsigned int(32) event_duration;
unsigned int(32) id;
} else if (version==1) {
unsigned int(32) timescale;
unsigned int(64) presentation_time;
unsigned int(32) event_duration;
unsigned int(32) id;
string scheme_id_uri;
string value;
}
unsigned int(8) message_data[];