About Custom File and Stream Handlers
Your application can use a custom file handler to read from a file or write to a file that is in a nonstandard format. To do this, your application simply uses the name of your file handler when opening the file or allocating the file interface. The AVIFile library then uses the functions from your file handler instead of those from another file handler. The nonstandard format appears as standard AVI data to your application or to any other application using your custom file handler.
Similarly, your application can use a custom stream handler to read a stream that is in a nonstandard format. A stream — whether it constitutes audio, video, MIDI, text, or custom data — is a component of an AVI file. For example, an AVI file that contains a video sequence, an English soundtrack, and a French soundtrack consists of three streams. Your application can specify the streams in an AVI file to process and direct each of those streams to a handler that can optimally process the appropriate type of multimedia data.