An incomplete reverse-engineer of the Widevine EME CDM request protobuf object.

widevinecdm.proto

// Used by https://github.com/use-sparingly/pywvpssh to automatically
// strip PSSH from MP4 files
package WidevineCDM;

message WvEmeRequest {
  required int32 version = 1; // 1

                   //start rlen end
  message Level1 { //0x02 1467 0x5BD

    message Level2 { //0x05 1378 0x567
        required int32 version = 1; // 1

        message Level3 { // 0x10 1260 0x4FC
            message Level4 { // 0x13 303 0x142?
              required int32 version = 1; // 2
              required string model = 2; // "ChromeCDM-Mac-x86"
              required sint64 unknown1_timestamp = 3;
              required bytes unknown2_bytes = 4; // possible license string
              required int32 unknown3 = 5;
            }
        }
    }
  }


}