No I don't think so... I removed the head inclusive the first --boundary-part and could the file open as a picture.
Now i tried it but I don't know how to convert from octet-stream to .jpg.
I can't run this script... I don't know why i've never worked with go... but i saw that the datafield should be converted in uint32 datas (in my case). I try to write a bash script which does this. But for the next two weeks I've holiday I think then won't happen very much. After my holidays I will go on on this topic.
I also saw this (Qt 利用海康摄像头的ISAPI协议进行抓图等操作_lynnhua_的博客-CSDN博客) but my chinese isn't very good
I've the solution now. It works with /ISAPI/Streaming/channels/2/picture. But I had the wrong Firmware, so it didn't work or me. With the correct Firmware it works.