mmioDescend这个函数啊??

[getoneking]

[code=C/C++]

MMCKINFO mmCkInfo ;
MMCKINFO ckIn ;

mmioDescend(hMMIO,&mmCkInfo,NULL,0); // 1行

ckIn.ckid = mmioFOURCC( 'f', 'm', 't', ' ' );

mmioDescend( hMMIO, &ckIn, &mmCkInfo, MMIO_FINDCHUNK ) ; // 2行

// mmioDescend( hMMIO, &ckIn, NULL, 0 ) ; // 3行

/code]
"mmioDescend"这个函数的第3个参数如何理解和运用呢？
当我将2行换成3行时ckIn这个变量的值是不变的，帮助文档上说：
If this parameter is not NULL, mmioDescend assumes the MMCKINFO structure it refers to was filled when mmioDescend was called to descend into the parent chunk, and mmioDescend searches for a chunk within the parent chunk.
这句话“mmioDescend searches for a chunk within the parent chunk.”如何理解？应该不是数据块里还有数据块吧，是不是在parent chunk之后查找chunk呢？

[AliasKavin]

建议参考以下资料~~
http://bbs.51cto.com/archiver/tid-462035.html
http://hi.baidu.com/freeeim/blog/item/083205cca55f531400e9281f.html

[gton08]

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