java 视频提取音频 | Java工具类

Posted 2021-11-08 剑客阿良_ALiang

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简述

将MP4视频内的音频提取出来，该工具类的解决思路如下：

1、提取视频音频pcm数据

2、将pcm数据封装音频头保存。

Maven依赖

        <dependency>
            <groupId>cn.hutool</groupId>
            <artifactId>hutool-all</artifactId>
            <version>5.5.2</version>
        </dependency>
        <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
            <optional>true</optional>
        </dependency>
        <dependency>
            <groupId>org.bytedeco</groupId>
            <artifactId>javacv-platform</artifactId>
            <version>1.5.5</version>
        </dependency>

说明一下，这里用到了hutools工具包，因为可以大幅简化代码。如果有自己的读取文件流的工具类，可以不使用。

代码

上代码

import cn.hutool.core.io.FileUtil;
import cn.hutool.core.lang.UUID;
import lombok.extern.slf4j.Slf4j;
import org.bytedeco.javacpp.Loader;

import java.io.BufferedOutputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.nio.file.Path;
import java.nio.file.Paths;
import java.util.Optional;

/** @Author huyi @Date 2021/10/20 12:11 @Description: mp4提取音频工具类 */
@Slf4j
public class Mp4ExtractAudioUtils {

  /**
   * 获取视频的文件pcm文件地址
   *
   * @param url MP4
   * @return
   * @throws Exception
   */
  public static String getMp4Pcm(String url, String tmpDir) throws Exception {
    Optional<String> pcmPath = Optional.empty();
    try {
      pcmPath = convertMP4toPCM(Paths.get(url), Paths.get(tmpDir));
    } catch (Exception exception) {
      exception.printStackTrace();
      throw new Exception("转换pcm异常:" + exception.getMessage());
    }
    if (pcmPath.isPresent()) {
      return pcmPath.get();
    } else {
      throw new Exception("视频转换音频失败");
    }
  }
  /**
   * 将单个PM4文件进行片头和片尾歌曲删除后，转换为PCM文件
   *
   * @param mp4Path
   * @param pcmDir
   * @return 转换完成后的pcm文件路径
   */
  public static Optional<String> convertMP4toPCM(Path mp4Path, Path pcmDir) {
    String ffmpeg = Loader.load(org.bytedeco.ffmpeg.ffmpeg.class);
    // 基于ffmpeg进行pcm转换
    // 基于输入路径的md5值来命名，也可以基于系统时间戳来命名
    String pcmFile = pcmDir.resolve(UUID.randomUUID() + ".pcm").toString();
    ProcessBuilder pcmBuilder =
        new ProcessBuilder(
            ffmpeg,
            "-y",
            "-i",
            mp4Path.toAbsolutePath().toString(),
            "-vn",
            "-acodec",
            "pcm_s16le",
            "-f",
            "s16le",
            "-ac",
            "1",
            "-ar",
            "16000",
            pcmFile);
    try {
      // inheritIO是指将 子流程的IO与当前java流程的IO设置为相同
      pcmBuilder.inheritIO().start().waitFor();
    } catch (InterruptedException | IOException e) {
      log.error("ffmpeg将mp4转换为pcm时出错", e);
      return Optional.empty();
    }
    // 返回pcm文件路径
    return Optional.of(pcmFile);
  }

  /**
   * 根据PCM文件构建wav的header字段
   *
   * @param srate Sample rate - 8000, 16000, etc.
   * @param channel Number of channels - Mono = 1, Stereo = 2, etc..
   * @param format Number of bits per sample (16 here)
   * @throws IOException
   */
  public static byte[] buildWavHeader(int dataLength, int srate, int channel, int format)
      throws IOException {
    byte[] header = new byte[44];

    long totalDataLen = dataLength + 36;
    long bitrate = srate * channel * format;

    header[0] = 'R';
    header[1] = 'I';
    header[2] = 'F';
    header[3] = 'F';
    header[4] = (byte) (totalDataLen & 0xff);
    header[5] = (byte) ((totalDataLen >> 8) & 0xff);
    header[6] = (byte) ((totalDataLen >> 16) & 0xff);
    header[7] = (byte) ((totalDataLen >> 24) & 0xff);
    header[8] = 'W';
    header[9] = 'A';
    header[10] = 'V';
    header[11] = 'E';
    header[12] = 'f';
    header[13] = 'm';
    header[14] = 't';
    header[15] = ' ';
    header[16] = (byte) format;
    header[17] = 0;
    header[18] = 0;
    header[19] = 0;
    header[20] = 1;
    header[21] = 0;
    header[22] = (byte) channel;
    header[23] = 0;
    header[24] = (byte) (srate & 0xff);
    header[25] = (byte) ((srate >> 8) & 0xff);
    header[26] = (byte) ((srate >> 16) & 0xff);
    header[27] = (byte) ((srate >> 24) & 0xff);
    header[28] = (byte) ((bitrate / 8) & 0xff);
    header[29] = (byte) (((bitrate / 8) >> 8) & 0xff);
    header[30] = (byte) (((bitrate / 8) >> 16) & 0xff);
    header[31] = (byte) (((bitrate / 8) >> 24) & 0xff);
    header[32] = (byte) ((channel * format) / 8);
    header[33] = 0;
    header[34] = 16;
    header[35] = 0;
    header[36] = 'd';
    header[37] = 'a';
    header[38] = 't';
    header[39] = 'a';
    header[40] = (byte) (dataLength & 0xff);
    header[41] = (byte) ((dataLength >> 8) & 0xff);
    header[42] = (byte) ((dataLength >> 16) & 0xff);
    header[43] = (byte) ((dataLength >> 24) & 0xff);

    return header;
  }

  /**
   * 默认写入的pcm数据是16000采样率，16bit，可以按照需要修改
   *
   * @param filePath
   * @param pcmData
   */
  public static String writeToFile(String filePath, byte[] pcmData) {
    BufferedOutputStream bos = null;
    try {
      bos = new BufferedOutputStream(new FileOutputStream(filePath));
      byte[] header = buildWavHeader(pcmData.length, 16000, 1, 16);
      bos.write(header, 0, 44);
      bos.write(pcmData);
      bos.close();
      return filePath;
    } catch (Exception e) {
      e.printStackTrace();
      return filePath;
    } finally {
      if (bos != null) {
        try {
          bos.close();
        } catch (IOException e) {
          e.printStackTrace();
        }
      }
    }
  }

  /**
   * 提取音频
   * @param mp4Path MP4地址
   * @param tmpDir 临时文件夹
   * @param resultPath 最终结果音频地址
   * @return 音频地址
   * @throws Exception 异常
   */
  public static String extractAudio(String mp4Path, String tmpDir, String resultPath)
      throws Exception {
    String pcmPath = getMp4Pcm(mp4Path, tmpDir);
    return writeToFile(resultPath, FileUtil.readBytes(pcmPath));
  }

  public static void main(String[] args) throws Exception {
    System.out.println(
        extractAudio(
            "C:\\\\Users\\\\huyi\\\\Desktop\\\\测试.mp4",
            "C:\\\\Users\\\\huyi\\\\Desktop",
            "C:\\\\Users\\\\huyi\\\\Desktop\\\\测试.wav"));
  }
}

执行结果：