关于视频抽帧调用虹软人脸识别的BufferedImage读取优化策略

背景说明：

1、在使用 FfmpegFrameGrabber 调用本地视频文件，逐帧读取视频内容

FFmpegFrameGrabber grabber = new FFmpegFrameGrabber(file);
// 不读取音频，否则frame.image = null
grabber.setAudioStream(-1);
grabber.start();

2、遍历所有帧

while(true){
    // 抓取目标帧
    Frame frame = grabber.grabFrame();
    if(frame == null){
        break;
    }
    if(frame.image == null){
      continue;
    }
}

3、frame转BufferedImage

在大部分的网站搜索中，通常使用Java2DFrameConverter 函数进行frame提取转换，

但占用过多CPU

import com.arcsoft.face.FaceInfo;
import com.arcsoft.face.enums.ImageFormat;
import com.arcsoft.face.toolkit.ImageFactory;
import com.arcsoft.face.toolkit.ImageInfo;import org.bytedeco.javacv.FFmpegFrameGrabber;
import org.bytedeco.javacv.Frame;
import org.bytedeco.javacv.Java2DFrameConverter;
import javax.imageio.ImageIO;
import java.awt.image.BufferedImage;
import java.io.ByteArrayOutputStream;
import java.nio.ByteBuffer;

Java2DFrameConverter jfc = new Java2DFrameConverter();
BufferedImage bufferedImage = jfc.getBufferedImage(frame);
ImageInfo imageInfo = ImageFactory.bufferedImage2ImageInfo(bufferedImage);

4、采用读取Frame.image直接获取

ImageInfo imageInfo = new ImageInfo();
imageInfo.setWidth(frame.imageWidth);
imageInfo.setHeight(frame.imageHeight);
imageInfo.setImageFormat(ImageFormat.CP_PAF_RGB24);
imageInfo.setImageData(convertByteArray((ByteBuffer)frame.image[0]));

private  byte[] convertByteArray(ByteBuffer buffer)   {
    int length = buffer.remaining();
    // 创建目标 byte[] 数组
    byte[] result = new byte[length];
    int offset = 0;
    // 复制每个 DirectByteBuffer 的内容到 byte[] 数组
    buffer.get(result, offset, length);
    buffer.rewind(); // 重置缓冲区位置
    return result;
}

部分参数的变动需要参考读取帧Frame对象的内容做适当调整

参考 Java2DFrameConverter 的 getBufferedImageType()

public static int getBufferedImageType(Frame frame) {
        int type = 0;
        if (frame.imageChannels == 1) {
            if (frame.imageDepth != 8 && frame.imageDepth != -8) {
                if (frame.imageDepth == 16) {
                    type = 11;
                }
            } else {
                type = 10;
            }
        } else if (frame.imageChannels == 3) {
            if (frame.imageDepth == 8 || frame.imageDepth == -8) {
                type = 5;
            }
        } else if (frame.imageChannels == 4 && (frame.imageDepth == 8 || frame.imageDepth == -8)) {
            type = 6;
        }

        return type;
    }