Writing Streams to a File

You can also create a file containing data streams by writing a new data stream to a file.

You can create a new stream in a new or existing file by using the AVIFileCreateStream function. This function defines a new stream according to the characteristics described in an AVISTREAMINFO structure, creates a stream interface for the new stream, increments the reference count of the stream, and returns the address of the stream-interface pointer.

Before you write the content of the stream, you must specify the stream format. You can set the stream format by using the AVIStreamSetFormat function. When setting the format of a video stream, you must supply this function with a BITMAPINFO structure containing the appropriate information. When setting the format of an audio stream, you must supply a WAVEFORMAT or WAVEFORMATEX structure containing the appropriate information. The information you need to supply to the function for other stream types depends on the stream type and the stream handler.

You can write the multimedia content in a stream by using the AVIStreamWrite function. This function copies raw data from an application-supplied buffer into the specified stream. The default AVI file handler appends information to the end of a stream. The default WAVE handler can write waveform-audio data within a stream as well as at the end of a stream.

You can write supplementary information about the file or stream that is not included in the AVIFileCreateStream or AVIStreamSetFormat function by using the AVIFileWriteData and AVIStreamWriteData functions. You can record data that is applicable to the entire file, such as copyright information and modification history, by using AVIFileWriteData. You can record stream-specific information, such as compression and decompression settings, by using AVIStreamWriteData. The supplementary information is stored in separate chunks within the file.

You can close the stream after you finish writing to the new stream by using the AVIStreamRelease function. This function clears buffers used in recording the stream data, and it completes and closes any incomplete data chunks in the file.