如何使用 JCodec 将一系列图像转换为视频？

Question

我正在尝试使用 JCodec 将一系列图像转换为 Java SE 桌面应用程序内的视频。我尝试的几种方法都导致 Windows Media Player 无法播放视频。

我不清楚这是编解码器问题（可疑）还是我没有正确创建视频。当我尝试在 Windows Media Player 中播放视频时，我得到：

Windows Media Player 无法播放该文件。玩家可能不会 支持文件类型或可能不支持用于 压缩文件。

这是我最近使用的拼凑示例。我真的不明白视频格式的内部原理，所以我什至不完全确定某些代码在做什么。

import java.awt.image.BufferedImage;
import java.io.File;
import java.io.IOException;
import java.nio.ByteBuffer;
import java.util.ArrayList;
import java.util.Arrays;

import javax.imageio.ImageIO;

import org.jcodec.codecs.h264.H264Encoder;
import org.jcodec.codecs.h264.H264Utils;
import org.jcodec.common.NIOUtils;
import org.jcodec.common.SeekableByteChannel;
import org.jcodec.common.model.ColorSpace;
import org.jcodec.common.model.Picture;
import org.jcodec.containers.mp4.Brand;
import org.jcodec.containers.mp4.MP4Packet;
import org.jcodec.containers.mp4.TrackType;
import org.jcodec.containers.mp4.muxer.FramesMP4MuxerTrack;
import org.jcodec.containers.mp4.muxer.MP4Muxer;
import org.jcodec.scale.AWTUtil;
import org.jcodec.scale.RgbToYuv420;

public class CreateVideo {
    private SeekableByteChannel ch;
    private Picture toEncode;
    private RgbToYuv420 transform;
    private H264Encoder encoder;
    private ArrayList<ByteBuffer> spsList;
    private ArrayList<ByteBuffer> ppsList;
    private FramesMP4MuxerTrack outTrack;
    private ByteBuffer _out;
    private int frameNo;
    private MP4Muxer muxer;

    public CreateVideo(File out) throws IOException {
        ch = NIOUtils.writableFileChannel(out);

        // Transform to convert between RGB and YUV
        transform = new RgbToYuv420(0, 0);

        // Muxer that will store the encoded frames
        muxer = new MP4Muxer(ch, Brand.MP4);

        // Add video track to muxer
        outTrack = muxer.addTrackForCompressed(TrackType.VIDEO, 25);

        // Allocate a buffer big enough to hold output frames
        _out = ByteBuffer.allocate(1920 * 1080 * 6);

        // Create an instance of encoder
        encoder = new H264Encoder();

        // Encoder extra data ( SPS, PPS ) to be stored in a special place of
        // MP4
        spsList = new ArrayList<ByteBuffer>();
        ppsList = new ArrayList<ByteBuffer>();

    }

    public void encodeImage(BufferedImage bi) throws IOException {
        if (toEncode == null) {
            toEncode = Picture.create(bi.getWidth(), bi.getHeight(), ColorSpace.YUV420);
        }

        // Perform conversion
        for (int i = 0; i < 3; i++) {
            Arrays.fill(toEncode.getData()[i], 0);
        }
        transform.transform(AWTUtil.fromBufferedImage(bi), toEncode);

        // Encode image into H.264 frame, the result is stored in '_out' buffer
        _out.clear();
        ByteBuffer result = encoder.encodeFrame(_out, toEncode);

        // Based on the frame above form correct MP4 packet
        spsList.clear();
        ppsList.clear();
        H264Utils.encodeMOVPacket(result, spsList, ppsList);

        // Add packet to video track
        outTrack.addFrame(new MP4Packet(result, frameNo, 25, 1, frameNo, true, null, frameNo, 0));

        frameNo++;
    }

    public void finish() throws IOException {
        // Push saved SPS/PPS to a special storage in MP4
        outTrack.addSampleEntry(H264Utils.createMOVSampleEntry(spsList, ppsList));

        // Write MP4 header and finalize recording
        muxer.writeHeader();
        NIOUtils.closeQuietly(ch);
    }

    public static void main(String[] args) throws IOException {
        CreateVideo encoder = new CreateVideo(new File("C:\\video\\video.mp4"));
        for (int i = 10; i < 34; i++) {
            String filename = String.format("C:\\video\\%02d.png", i);
            BufferedImage bi = ImageIO.read(new File(filename));
            encoder.encodeImage(bi);
        }
        encoder.finish();
    }
}

如果有一些更简单的编解码器/容器，我不依赖于 H264 或 MP4。唯一的要求是它应该在没有安装额外软件的情况下在基准 Windows 7 机器上运行。

Answer 1

jcodec 的 RgbToYuv420() 转换有很多问题。
我使用自己的函数将 RGB BufferedImage 转换为 Yuv420。
我遇到的一个问题是 RgbToYuv420 平均计算的 upix 和 vpix 值，这导致我的 mp4 中的颜色都很不稳定。

// make a YUV420J out of BufferedImage pixels
private Picture makeFrame(BufferedImage bi, ColorSpace cs)
{   
    DataBuffer imgdata = bi.getRaster().getDataBuffer();
    int[] ypix = new int[imgdata.getSize()];
    int[] upix = new int[ imgdata.getSize() >> 2 ];
    int[] vpix = new int[ imgdata.getSize() >> 2 ];
    int ipx = 0, uvoff = 0;

    for (int h = 0; h < bi.getHeight(); h++) {
        for (int w = 0; w < bi.getWidth();  w++) {
            int elem = imgdata.getElem(ipx);
            int r = 0x0ff & (elem >>> 16);
            int g = 0x0ff & (elem >>> 8);
            int b = 0x0ff & elem;
            ypix[ipx] = ((66 * r + 129 * g + 25 * b) >> 8) + 16;
            if ((0 != w % 2) && (0 != h % 2)) {
                upix[uvoff] = (( -38 * r + -74 * g + 112 * b) >> 8) + 128;
                vpix[uvoff] = (( 112 * r + -94 * g + -18 * b) >> 8) + 128;
                uvoff++;
            }
            ipx++;
        }
    }
    int[][] pix = { ypix, upix, vpix, null };
    // old API
    // return new Picture(bi.getWidth(), bi.getHeight(), pix, ColorSpace.YUV420J);
    return Picture.createPicture(bi.getWidth(), bi.getHeight(), pix, ColorSpace.YUV420J);
}

Answer 2

现在有了 0.2.0 https://github.com/jcodec/jcodec/blob/master/javase/src/main/java/org/jcodec/api/awt/AWTSequenceEncoder8Bit.java

此示例创建一个具有固定背景和叠加动画的 MP4。没有声音。

    AWTSequenceEncoder8Bit enc = AWTSequenceEncoder8Bit.create2997Fps(outputMovieFile); 
    int framesToEncode = (int) (29.97 * durationInSeconds);
    java.awt.image.BufferedImage image = ...(some background image)

    for (int frameIndx = 0, x = 0, y = 0, incX = speed, incY = speed; frameIndx < framesToEncode; frameIndx++, x += incX, y += incY) {
        Graphics g = image.getGraphics();
        g.setColor(Color.YELLOW);
        if (x >= image.getWidth() - ballSize) incX = -speed;
        if (y >= image.getHeight() - ballSize) incY = -speed;
        if (x <= 0) incX = speed;
        if (y <= 0) incY = speed;
        g.fillOval(x, y, ballSize, ballSize);
        enc.encodeImage(image);
    }
    enc.finish();