Getting raw binary from mixed Buffer

Having following nodeJS Buffer().toString('utf8'):

Content-Type: audio/x-ms-wma
Content-Disposition: form-data; name=recordedAudio
\r\n\r\n0&�u�f�\u0011��\u0000�

I need to remove headers (Content-Type/Disposition) and get the raw audio data. If I simply replace headers with replace method I am not able to convert UTF-8 audio back to Buffer properly.

How can it be done?

via YasiuMaster