Function retrieve value of Mediainfo field with given parameters.
Get(FieldID [, Context [, Stream]]) Get(FieldIndex [, Context [, Stream]])
| FieldID | Text ID of library field. |
| FieldIndex | Index of library field. |
| Context | Context (General, Video, etc.). If omitted, General context will be used. |
| Stream | Stream number. If omitted, stream 0 will be used. Total count of strams can be retrieved with GetCount function. |
Function return string with field's value.