public static extern int WebPDemuxPrevChunk(WebPChunkIterator *iter);
public static extern void WebPDemuxReleaseChunkIterator(WebPChunkIterator *iter);
public static extern int WebPDemuxGetChunk([NativeTypeName("const WebPDemuxer *")] WebPDemuxer *dmux, [NativeTypeName("const char [4]")] sbyte *fourcc, int chunk_number, WebPChunkIterator *iter);