从javascript发送application / octet-stream并在Internet Explorer中使用PHP file_get_contents读取它

Here is my client JS app sending a binary file

var arrayBuffer = <FileReader readAsArrayBuffer result>;
var myRequest = new XMLHttpRequest();
myRequest.open(
    'POST',
    myUrl
);
myRequest.setRequestHeader("Content-Type","application/octet-stream");
myRequest.setRequestHeader("SomeOtherHeader", someNumber);
var dataView = new DataView(arrayBuffer);
...
myRequest.send(dataView);

Then I get this request with PHP on the server

<?php

$request = file_get_contents('php://input');
error_log($request);
...

Sending data (an image) with Chrome and Firefox I get in the logs some binary chars (as expected) instead Internet Explorer 11 I get the string [Object object] and so I am not sure how to parse this data