从avi格式的视频中提取bmp格式的关键帧，以达到压缩空间的效果。-Avi video format from bmp format to extract the key frames to achieve the effect of compressed space.

压缩域的视频I帧提取，提取出来的关键帧作为视频的关键帧，用于视频拷贝检测-Compressed domain video I frame extraction, the extracted key frames as a video keyframe for video copy detection