GPUimage 遇到的崩溃及问题

做视频滤镜时，遇到崩溃，记录一下：
1：
@interface vVideoFilter()
{
//不崩
GPUImageMovie *_movieFile;
GPUImageOutput<GPUImageInput> *_filter;
GPUImageMovieWriter *_movieWriter;
}

//这样写就会崩溃，原因还不知
@property(nonatomic,strong)GPUImageMovie *movieFile;
@property(nonatomic,strong)GPUImageOutput<GPUImageInput> *filter;
@property(nonatomic,strong)GPUImageMovieWriter *movieWriter;

@end

2：显示视频的View，要是GPUImageView，否则也会崩溃。

3：路径不对，
NSURL* url = [NSURL fileURLWithPath:filePath],要这样。不能
[NSURL URLWithString:filePath]