从android中的视频中提取MP3格式的音频

Question

我想在android中将视频文件转换为mp3文件。

我正在使用以下代码将视频转换为 MP3：

File source = new File(sourceFile);
File target = new File(destFile);
audioAttributes = new AudioAttributes();

audioAttributes.setCodec("libmp3lame");
audioAttributes.setBitRate(new Integer(128000));
audioAttributes.setChannels(new Integer(2));
audioAttributes.setSamplingRate(new Integer(44100));

EncodingAttributes encodingAttributes = new EncodingAttributes();
encodingAttributes.setFormat("mp3");
encodingAttributes.setAudioAttributes(audioAttributes);

Encoder encoder = new Encoder();

try {
    encoder.encode(source, target, encodingAttributes);
} catch (EncoderException e) {
    e.printStackTrace();
}

但它不起作用。这是我得到的错误：

java.io.IOException: Error running exec(). Command: [/bin/chmod, 755, /data/data/com.example.videotomp3_demo/cache/jave-1/ffmpeg] Working Directory: null Environment: null
12-01 15:19:04.116 19702-19702/com.example.videotomp3_demo W/System.err:     at java.lang.ProcessManager.exec(ProcessManager.java:211)
12-01 15:19:04.116 19702-19702/com.example.videotomp3_demo W/System.err:     at java.lang.Runtime.exec(Runtime.java:173)
12-01 15:19:04.116 19702-19702/com.example.videotomp3_demo W/System.err:     at java.lang.Runtime.exec(Runtime.java:128)
12-01 15:19:04.116 19702-19702/com.example.videotomp3_demo W/System.err:     at it.sauronsoftware.jave.DefaultFFMPEGLocator.<init>(DefaultFFMPEGLocator.java:85)
12-01 15:19:04.116 19702-19702/com.example.videotomp3_demo W/System.err:     at it.sauronsoftware.jave.Encoder.<init>(Encoder.java:111)
12-01 15:19:04.116 19702-19702/com.example.videotomp3_demo W/System.err:     at com.example.videotomp3_demo.MainActivity.onCreate(MainActivity.java:50)
12-01 15:19:04.116 19702-19702/com.example.videotomp3_demo W/System.err:     at android.app.Activity.performCreate(Activity.java:6005)
12-01 15:19:04.116 19702-19702/com.example.videotomp3_demo W/System.err:     at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1111)
12-01 15:19:04.116 19702-19702/com.example.videotomp3_demo W/System.err:     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2446)
12-01 15:19:04.116 19702-19702/com.example.videotomp3_demo W/System.err:     at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2555)
12-01 15:19:04.116 19702-19702/com.example.videotomp3_demo W/System.err:     at android.app.ActivityThread.access$800(ActivityThread.java:176)
12-01 15:19:04.116 19702-19702/com.example.videotomp3_demo W/System.err:     at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1437)
12-01 15:19:04.116 19702-19702/com.example.videotomp3_demo W/System.err:     at android.os.Handler.dispatchMessage(Handler.java:111)
12-01 15:19:04.116 19702-19702/com.example.videotomp3_demo W/System.err:     at android.os.Looper.loop(Looper.java:194)
12-01 15:19:04.116 19702-19702/com.example.videotomp3_demo W/System.err:     at android.app.ActivityThread.main(ActivityThread.java:5576)
12-01 15:19:04.116 19702-19702/com.example.videotomp3_demo W/System.err:     at java.lang.reflect.Method.invoke(Native Method)
12-01 15:19:04.116 19702-19702/com.example.videotomp3_demo W/System.err:     at java.lang.reflect.Method.invoke(Method.java:372)
12-01 15:19:04.116 19702-19702/com.example.videotomp3_demo W/System.err:     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:956)
12-01 15:19:04.116 19702-19702/com.example.videotomp3_demo W/System.err:     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:751)
12-01 15:19:04.116 19702-19702/com.example.videotomp3_demo W/System.err: Caused by: java.io.IOException: No such file or directory
12-01 15:19:04.116 19702-19702/com.example.videotomp3_demo W/System.err:     at java.lang.ProcessManager.exec(Native Method)
12-01 15:19:04.116 19702-19702/com.example.videotomp3_demo W/System.err:     at java.lang.ProcessManager.exec(ProcessManager.java:209)

知道什么地方出了问题吗？

Answer 1

FFmpeg 正在增加应用程序的大小。经过大量调试和研究，我创建了一个使用 Android 的默认声音 API (MediaExtractor & MediaMuxer) 的要点。您可以通过给定的URL 进行检查。

这可以很简单的完成下面提到的操作，

从视频中提取音频：

new AudioExtractor().genVideoUsingMuxer(videoFile, originalAudio, -1, -1, true, false);

从视频中提取视频（静音）：

new AudioExtractor().genVideoUsingMuxer(videoFile, originalAudio, -1, -1, false, true);

从头开始裁剪视频：

new AudioExtractor().genVideoUsingMuxer(videoFile, originalAudio, timeFromWhereToStart, -1, true, true);

从结尾裁剪视频：

new AudioExtractor().genVideoUsingMuxer(videoFile, originalAudio, -1, timeFromWhereToEnd, true, true);

（其中 videoFile 是输入文件路径， originalAudio 是输出文件路径）

Answer 2

在安卓上使用FFMPEG 你需要实现一个方法（我认为它已经存在于 ffmpeg 库中） 您可以使用以下命令提取音频

ffmpeg -i input-video.avi -vn -acodec copy output-audio.aac

Answer 3

不要使用 ffmpeg，而是使用 android MediaExtractor 和 MediaMuxer。这适用于所有 android 版本，包括 android 11。

public class AudioUtils {

private static final String TAG = "AudioUtils";
private static final int DEFAULT_BUFFER_SIZE = 1 * 1024 * 1024;

public void genVideoUsingMuxer(FileDescriptor srcPath, FileDescriptor dstPathFd, String dstPath, int startMs, int endMs, boolean useAudio, boolean useVideo) throws IOException {
    // Set up MediaExtractor to read from the source.
    MediaExtractor extractor = new MediaExtractor();
    extractor.setDataSource(srcPath);
    int trackCount = extractor.getTrackCount();
    // Set up MediaMuxer for the destination.
    MediaMuxer muxer;
    if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.Q) {
        muxer = new MediaMuxer(dstPathFd, MediaMuxer.OutputFormat.MUXER_OUTPUT_MPEG_4);
    } else {
        muxer = new MediaMuxer(dstPath, MediaMuxer.OutputFormat.MUXER_OUTPUT_MPEG_4);
    }

    // Set up the tracks and retrieve the max buffer size for selected
    // tracks.
    HashMap<Integer, Integer> indexMap = new HashMap<Integer, Integer>(trackCount);
    int bufferSize = -1;
    for (int i = 0; i < trackCount; i++) {
        MediaFormat format = extractor.getTrackFormat(i);
        String mime = format.getString(MediaFormat.KEY_MIME);
        boolean selectCurrentTrack = false;
        if (mime.startsWith("audio/") && useAudio) {
            selectCurrentTrack = true;
        } else if (mime.startsWith("video/") && useVideo) {
            selectCurrentTrack = true;
        }
        if (selectCurrentTrack) {
            extractor.selectTrack(i);
            int dstIndex = muxer.addTrack(format);
            indexMap.put(i, dstIndex);
            if (format.containsKey(MediaFormat.KEY_MAX_INPUT_SIZE)) {
                int newSize = format.getInteger(MediaFormat.KEY_MAX_INPUT_SIZE);
                bufferSize = newSize > bufferSize ? newSize : bufferSize;
            }
        }
    }
    if (bufferSize < 0) {
        bufferSize = DEFAULT_BUFFER_SIZE;
    }
    // Set up the orientation and starting time for extractor.
    MediaMetadataRetriever retrieverSrc = new MediaMetadataRetriever();
    retrieverSrc.setDataSource(srcPath);
    String degreesString = retrieverSrc.extractMetadata(MediaMetadataRetriever.METADATA_KEY_VIDEO_ROTATION);
    if (degreesString != null) {
        int degrees = Integer.parseInt(degreesString);
        if (degrees >= 0) {
            muxer.setOrientationHint(degrees);
        }
    }
    if (startMs > 0) {
        extractor.seekTo(startMs * 1000, MediaExtractor.SEEK_TO_CLOSEST_SYNC);
    }
    // Copy the samples from MediaExtractor to MediaMuxer. We will loop
    // for copying each sample and stop when we get to the end of the source
    // file or exceed the end time of the trimming.
    int offset = 0;
    int trackIndex = -1;
    ByteBuffer dstBuf = ByteBuffer.allocate(bufferSize);
    MediaCodec.BufferInfo bufferInfo = new MediaCodec.BufferInfo();
    muxer.start();
    while (true) {
        bufferInfo.offset = offset;
        bufferInfo.size = extractor.readSampleData(dstBuf, offset);
        if (bufferInfo.size < 0) {
            Log.d(TAG, "Saw input EOS.");
            bufferInfo.size = 0;
            break;
        } else {
            bufferInfo.presentationTimeUs = extractor.getSampleTime();
            if (endMs > 0 && bufferInfo.presentationTimeUs > (endMs * 1000)) {
                Log.d(TAG, "The current sample is over the trim end time.");
                break;
            } else {
                bufferInfo.flags = extractor.getSampleFlags();
                trackIndex = extractor.getSampleTrackIndex();
                muxer.writeSampleData(indexMap.get(trackIndex), dstBuf, bufferInfo);
                extractor.advance();
            }
        }
    }
    muxer.stop();
    muxer.release();
    return;
}

}

这就是你调用方法的方式。

  new AudioUtils().genVideoUsingMuxer(inputVideoFileDescriptor, outputAudioFileDescriptor, destPath, -1, -1, true, false);

示例：

String destPath = Environment.getExternalStoragePublicDirectory("") + "/AudFolder2/asd.mp3"
try {
        FileDescriptor outputAudioFileDescriptor = getActivity().getContentResolver().openFileDescriptor(outputAudioUri, "w").getFileDescriptor();
        
  FileDescriptor inputVideoFileDescriptor = getActivity().getContentResolver().openFileDescriptor(Uri.parse(inputVideoUri), "r").getFileDescriptor();

        new AudioUtils().genVideoUsingMuxer(pfdVideo.getFileDescriptor(), pfdAudio.getFileDescriptor(), destPath, -1, -1, true, false);
    } catch (IOException e) {
        e.printStackTrace();
        Log.e(TAG, "saveAudioToDevice: ERROR = "+ e.getMessage() );
    }