Functions22

DataCodecCompress

The DataCodecCompress function compresses data using the specified compressor component.



 
pascal ComponentResult DataCodecCompress (

                     DataCodecComponent dc, 

                     void *srcData, 

                     UInt32 srcSize, 

                     void *dstData, 

                     UInt32 dstBufferSize, 

                     UInt32 *actualDstSize,

                     UInt32 *decompressSlop );

dc: Specifies the compressor component to used.
srcData: Contains a pointer to the data to be compressed.
srcSize: Contains the size of the data to be compressed, in bytes.
dstData: Contains a pointer to the buffer in which to store the compressed data.
dstBufferSize: Contains the size of the buffer in which to store the compressed data, in bytes.
actualDstSize: Contains the size of the compressed data that was created, in bytes.
decompressSlop: Contains the number of bytes that should be added to the decompression buffer size if decompression occurs in place.

DISCUSSION

Before calling the DataCodecCompress function, you should call the DataCodecGetCompressBufferSize function to obtain the maximum possible size of the compressed data that will be returned. You can then use this value as the value of the dstBufferSize parameter. Note that a buffer for compressed data that is the same size as the uncompressed data may not be large enough: in some cases, the size of the compressed data can be larger than the size of the decompressed data.

When you compress data, you should store the size of data before compression at the beginning of the file, immediately before the compressed data. This allows you to obtain the size of the decompressed data and allocate the buffer for storing the decompressed data before calling the DataCodecDecompress function.

You can compress sprites by calling the DataCodecCompress function. If you do, you must

Include the uncompressed size of the sample at the beginning of the sample, before the compressed data.
Store the component subtype of the data compressor used to compress the sprite in the decompressorType field of the sample's sprite sample description.

You can compress 3D media samples by calling the DataCodecCompress function. If you do, you must

Include the uncompressed size of the sample at the beginning of the sample, before the compressed data.
Store the component subtype of the data compressor used to compress the sprite in the decompressorType field of the sample's sprite sample description.

DataCodecDecompress

The DataCodecDecompress function decompresses data using the specified compressor component.



 
pascal ComponentResult DataCodecDecompress (

                     DataCodecComponent dc, 

                     void *srcData, 

                     UInt32 srcSize, 

                     void *dstData, 

                     UInt32 dstBufferSize );

dc: Specifies the decompressor component to used.
srcData: Contains a pointer to the data to be decompressed.
srcSize: Contains the size of the data to be decompressed, in bytes.
dstData: Contains a pointer to the buffer in which to store the decompressed data.
dstBufferSize: Contains the size of the buffer in which to store the decompressed data, in bytes.

DISCUSSION

Before allocating the buffer in which to store decompressed data, you need to get the size of the decompressed data. The size is normally stored at the beginning of the file, immediately before the compressed data.

Functions

DataCodecCompress

DISCUSSION

DataCodecDecompress

DISCUSSION

Performing Compression and Decompression at Interrupt Time