使用javacv中的ffmpeg實現錄屏，結果連運行都失敗了，現在終於解決了

前言：

今天突發奇想，想自己寫一個錄屏的軟件，上次寫了一個專門錄音的Demo，但是要把聲音和視頻放到一起合成一個mp4文件，着實有一點艱難，所以就打算使用ffmpeg來寫一個，而這篇博客中會順便談一談我碰到的各種坑。
ffmpeg是一個c++程序，要想在java中使用ffmpeg，無非就是兩種方式：直接在java程序中調用ffmpeg.exe，還有就是通過jni的方式。而在這裏我就是使用jni的方式，但是我在這裏直接使用javacv這個框架來實現就可以，用這個的好處就是你什麼都不要幹，直接導入幾個重要的jar包就可以。

步驟：

首先呢，下載javacv就可以：github下載
你也可以直接在我這裏下載
然後下載好了，就要開始導包了，導入javacpp，javacv，這2個一定要導，另外要能使用ffmpeg的API實現錄屏就要再導入
ffmpeg-windows-x86_64.jar
ffmpeg-platform.jar
ffmpeg.jar
videoinput.jar

導完包之後代碼測試一下，這裏發一個別人寫的代碼，可以實現錄屏，但不能錄音，代碼裏面需要修改一下存放文件的路徑：

package com;

import java.awt.AWTException;
import java.awt.Graphics2D;
import java.awt.Rectangle;
import java.awt.RenderingHints;
import java.awt.Robot;
import java.awt.Toolkit;
import java.awt.image.BufferedImage;
import java.nio.ByteBuffer;
import java.nio.ByteOrder;
import java.nio.ShortBuffer;
import java.util.Scanner;
import java.util.concurrent.ScheduledThreadPoolExecutor;
import java.util.concurrent.TimeUnit;

import javax.sound.sampled.AudioFormat;
import javax.sound.sampled.AudioSystem;
import javax.sound.sampled.DataLine;
import javax.sound.sampled.LineUnavailableException;
import javax.sound.sampled.TargetDataLine;

import org.bytedeco.ffmpeg.global.avcodec;
import org.bytedeco.ffmpeg.global.avutil;

import org.bytedeco.javacv.FFmpegFrameRecorder;
import org.bytedeco.javacv.Frame;
import org.bytedeco.javacv.FrameRecorder.Exception;
import org.bytedeco.javacv.Java2DFrameConverter;

	/**
 * 使用javacv進行錄屏
 * 
 */
public class VideoRecord {
	
	//線程池 screenTimer
	private ScheduledThreadPoolExecutor screenTimer;
	//獲取屏幕尺寸
	private final Rectangle rectangle = new Rectangle(Constant.WIDTH, Constant.HEIGHT); // 截屏的大小
	//視頻類 FFmpegFrameRecorder
	private FFmpegFrameRecorder recorder;
	private Robot robot;
	//線程池 exec
	private ScheduledThreadPoolExecutor exec;
	private TargetDataLine line;
	private AudioFormat audioFormat;
	private DataLine.Info dataLineInfo;
	private boolean isHaveDevice = true;
	private long startTime = 0;
	private long videoTS = 0;
	private long pauseTime = 0;
	private double frameRate = 5;

	public VideoRecord(String fileName, boolean isHaveDevice) {
		// TODO Auto-generated constructor stub
		recorder = new FFmpegFrameRecorder(fileName + ".mp4", Constant.WIDTH, Constant.HEIGHT);
		// recorder.setVideoCodec(avcodec.AV_CODEC_ID_H265); // 28
		// recorder.setVideoCodec(avcodec.AV_CODEC_ID_FLV1); // 28
		recorder.setVideoCodec(avcodec.AV_CODEC_ID_MPEG4); // 13
		recorder.setFormat("mp4");
		// recorder.setFormat("mov,mp4,m4a,3gp,3g2,mj2,h264,ogg,MPEG4");
		recorder.setSampleRate(44100);
		recorder.setFrameRate(frameRate);
		recorder.setVideoQuality(0);
		recorder.setVideoOption("crf", "23");
		// 2000 kb/s, 720P視頻的合理比特率範圍
		recorder.setVideoBitrate(1000000);
		/**
		 * 權衡quality(視頻質量)和encode speed(編碼速度) values(值)： ultrafast(終極快),superfast(超級快),
		 * veryfast(非常快), faster(很快), fast(快), medium(中等), slow(慢), slower(很慢),
		 * veryslow(非常慢)
		 * ultrafast(終極快)提供最少的壓縮（低編碼器CPU）和最大的視頻流大小；而veryslow(非常慢)提供最佳的壓縮（高編碼器CPU）的同時降低視頻流的大小
		 * 參考：https://trac.ffmpeg.org/wiki/Encode/H.264 官方原文參考：-preset ultrafast as the
		 * name implies provides for the fastest possible encoding. If some tradeoff
		 * between quality and encode speed, go for the speed. This might be needed if
		 * you are going to be transcoding multiple streams on one machine.
		 */
		recorder.setVideoOption("preset", "slow");
		recorder.setPixelFormat(avutil.AV_PIX_FMT_YUV420P); // yuv420p
		recorder.setAudioChannels(2);
		recorder.setAudioOption("crf", "0");
		// Highest quality
		recorder.setAudioQuality(0);
		recorder.setAudioCodec(avcodec.AV_CODEC_ID_AAC);
		try {
			robot = new Robot();
		} catch (AWTException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
		try {
			recorder.start();
		} catch (Exception e) {
			// TODO Auto-generated catch block
			System.out.print("*******************************");
		}
		this.isHaveDevice = isHaveDevice;
	}

	/**
	 * 開始錄製
	 */
	public void start() {

		if (startTime == 0) {
			startTime = System.currentTimeMillis();
		}
		if (pauseTime == 0) {
			pauseTime = System.currentTimeMillis();
		}
		// 如果有錄音設備則啓動錄音線程
		if (isHaveDevice) {
			new Thread(new Runnable() {

				@Override
				public void run() {
					// TODO Auto-generated method stub
					caputre();
				}
			}).start();

		}

		// 錄屏
		screenTimer = new ScheduledThreadPoolExecutor(1);
		screenTimer.scheduleAtFixedRate(new Runnable() {
			@Override
			public void run() {

				// 將screenshot對象寫入圖像文件
				// try {
				// ImageIO.write(screenCapture, "JPEG", f);
				// videoGraphics.drawImage(screenCapture, 0, 0, null);
				// IplImage image = cvLoadImage(name); // 非常喫內存！！
				// // 創建一個 timestamp用來寫入幀中
				// videoTS = 1000
				// * (System.currentTimeMillis() - startTime - (System.currentTimeMillis() -
				// pauseTime));
				// // 檢查偏移量
				// if (videoTS > recorder.getTimestamp()) {
				// recorder.setTimestamp(videoTS);
				// }
				BufferedImage screenCapture = robot.createScreenCapture(rectangle); // 截屏
				
				BufferedImage videoImg = new BufferedImage(Constant.WIDTH, Constant.HEIGHT,
						BufferedImage.TYPE_3BYTE_BGR); // 聲明一個BufferedImage用重繪截圖
				
				Graphics2D videoGraphics = videoImg.createGraphics();// 創建videoImg的Graphics2D
				
				videoGraphics.setRenderingHint(RenderingHints.KEY_DITHERING, RenderingHints.VALUE_DITHER_DISABLE);
				videoGraphics.setRenderingHint(RenderingHints.KEY_COLOR_RENDERING,
						RenderingHints.VALUE_COLOR_RENDER_SPEED);
				videoGraphics.setRenderingHint(RenderingHints.KEY_RENDERING, RenderingHints.VALUE_RENDER_SPEED);
				videoGraphics.drawImage(screenCapture, 0, 0, null); // 重繪截圖
				
				Java2DFrameConverter java2dConverter = new Java2DFrameConverter();
				
				Frame frame = java2dConverter.convert(videoImg);
				try {
					videoTS = 1000L
							* (System.currentTimeMillis() - startTime - (System.currentTimeMillis() - pauseTime));
					// 檢查偏移量
					if (videoTS > recorder.getTimestamp()) {
						recorder.setTimestamp(videoTS);
					}
					recorder.record(frame); // 錄製視頻
				} catch (Exception e) {
					// TODO Auto-generated catch block
					e.printStackTrace();
				}
				// 釋放資源
				videoGraphics.dispose();
				videoGraphics = null;
				videoImg.flush();
				videoImg = null;
				java2dConverter = null;
				screenCapture.flush();
				screenCapture = null;

			}
		}, (int) (1000 / frameRate), (int) (1000 / frameRate), TimeUnit.MILLISECONDS);

	}

	/**
	 * 抓取聲音
	 */
	public void caputre() {
		audioFormat = new AudioFormat(44100.0F, 16, 2, true, false);
		dataLineInfo = new DataLine.Info(TargetDataLine.class, audioFormat);
		try {
			line = (TargetDataLine) AudioSystem.getLine(dataLineInfo);
		} catch (LineUnavailableException e1) {
			// TODO Auto-generated catch block
			System.out.println("#################");
		}
		try {
			line.open(audioFormat);
		} catch (LineUnavailableException e1) {
			// TODO Auto-generated catch block
			e1.printStackTrace();
		}
		line.start();

		final int sampleRate = (int) audioFormat.getSampleRate();
		final int numChannels = audioFormat.getChannels();

		int audioBufferSize = sampleRate * numChannels;
		final byte[] audioBytes = new byte[audioBufferSize];

		exec = new ScheduledThreadPoolExecutor(1);
		exec.scheduleAtFixedRate(new Runnable() {
			@Override
			public void run() {
				try {
					int nBytesRead = line.read(audioBytes, 0, line.available());
					int nSamplesRead = nBytesRead / 2;
					short[] samples = new short[nSamplesRead];

					// Let's wrap our short[] into a ShortBuffer and
					// pass it to recordSamples
					ByteBuffer.wrap(audioBytes).order(ByteOrder.LITTLE_ENDIAN).asShortBuffer().get(samples);
					ShortBuffer sBuff = ShortBuffer.wrap(samples, 0, nSamplesRead);

					// recorder is instance of
					// org.bytedeco.javacv.FFmpegFrameRecorder
					recorder.recordSamples(sampleRate, numChannels, sBuff);
					// System.gc();
				} catch (org.bytedeco.javacv.FrameRecorder.Exception e) {
					e.printStackTrace();
				}
			}
		}, (int) (1000 / frameRate), (int) (1000 / frameRate), TimeUnit.MILLISECONDS);
	}

	/**
	 * 停止
	 */
	public void stop() {
		if (null != screenTimer) {
			screenTimer.shutdownNow();
		}
		try {
			recorder.stop();
			recorder.release();
			recorder.close();
			screenTimer = null;
			// screenCapture = null;
			if (isHaveDevice) {
				if (null != exec) {
					exec.shutdownNow();
				}
				if (null != line) {
					line.stop();
					line.close();
				}
				dataLineInfo = null;
				audioFormat = null;
			}
		} catch (Exception e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}

	}

	/**
	 * 暫停
	 * 
	 * @throws Exception
	 */
	public void pause() throws Exception {
		screenTimer.shutdownNow();
		screenTimer = null;
		if (isHaveDevice) {
			exec.shutdownNow();
			exec = null;
			line.stop();
			line.close();
			dataLineInfo = null;
			audioFormat = null;
			line = null;
		}
		pauseTime = System.currentTimeMillis();
	}

	public static void main(String[] args) throws Exception, AWTException {
		VideoRecord videoRecord = new VideoRecord("C:\\Users\\Administrator\\Desktop\\視頻", false);
		videoRecord.start();
		while (true) {
			System.out.println("你要停止嗎？請輸入(stop)，程序會停止。");
			Scanner sc = new Scanner(System.in);
			if (sc.next().equalsIgnoreCase("stop")) {
				videoRecord.stop();
				System.out.println("停止");
			}
			if (sc.next().equalsIgnoreCase("pause")) {
				videoRecord.pause();
				System.out.println("暫停");
			}
			if (sc.next().equalsIgnoreCase("start")) {
				videoRecord.start();
				System.out.println("開始");
			}
		}
	}
}

class Constant{
	public final static int WIDTH=Toolkit.getDefaultToolkit().getScreenSize().width;
	public final static int HEIGHT=Toolkit.getDefaultToolkit().getScreenSize().height;

}

如果你能成功stop並保存一個視頻文件，那就說明可以使用ffmpeg了。

我碰到的各種坑：

1）import的時候，一些函數什麼的找不到定義。像這兩個，在我copy的代碼中是org.bytedeco.javacpp.avcodec和org.bytedeco.javacpp.avutil，但包里根本找不到，後面找了找發現是在ffmpeg.jar包下，所以要改成
import org.bytedeco.ffmpeg.global.avcodec;
import org.bytedeco.ffmpeg.global.avutil;
2）少導入了一些jar包，因爲我看其他人的博客，只要導入javacpp，javacv就可以，這是最讓人崩潰的，搞得我一直找不到到底是哪的問題，後來一股腦全給導進來又可以了，然後一步步去排除，才找到了哪些jar包。因爲這個我找了幾天的博客，差點就放棄了。

下一篇博客，是對上面代碼的完善：javacv利用ffmpeg實現錄屏和錄音，輸出爲mp4文件