Examples of useful converters include encryption and compression filters. These converters do not change the interface to Channels, hence their effect is transparent to the application support for memory-mapping disc files. This means that the entire file contents are mapped into the process virtual memory space. Not having to read the file contents can save an enormous amount of time of you only need to access a small part of the data. Memory mapping places that burden on the operating system memory-based Channels which do not require any file storage.
Tutorials Below are a few simple examples which show how to use Channels.
The first line contains the horizontal and vertical lengths. The remaining lines contain the array data. The first two words contain the size of the array and the rest of the file contains the binary single precision floating point data. So one would not use such a file format in real life. The point of this example is to show how to use memory-mapping to avoid slow reading.