QuickTime 4 Reference

Initializing Your Decompressor Component

The first function call that your image decompressor component receives from the base image decompressor is always a call to ImageCodecInitialize . In response to this call, your image decompressor component returns an ImageSubCodecDecompressCapabilities structure that specifies its capabilities. This structure contains the following fields:

canAsync specifies whether the component can support asynchronous decompression operations, as described in "Asynchronous Decompression" (page 223) .
decompressRecordSize specifies the size of the ImageSubCodecDecompressRecord structure that the base decompressor component creates for your image decompressor component.

With the help of the base image decompressor, any image decompressor that uses only interrupt-safe calls for decompression operations can support asynchronous decompression.

Listing 2 shows how to specify that a decompressor supports asynchronous decompression operations.

Listing 2 Specifying the capabilities of a decompressor component



 
ImageSubCodecDecompressCapabilities deccap;

ImageSubCodecDecompressRecord decrec;



deccap->decompressRecordSize = sizeof(decrec);

deccap->canAsync = true;