java - 使用 Android MediaRecorder 录制 webm

Question

我在从 mp4 切换到 webm 录制时遇到了一些问题。

此代码以 24fps 和 640x480 分辨率录制 mp4 音频

private boolean prepareVideoRecorder(){

    // BEGIN_INCLUDE (configure_preview)

    if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.M) {
        if(     ( checkSelfPermission(android.Manifest.permission.CAMERA)
                    == PackageManager.PERMISSION_GRANTED ) &&
                (checkSelfPermission(android.Manifest.permission.RECORD_AUDIO)
                    == PackageManager.PERMISSION_GRANTED ) &&
                (checkSelfPermission(android.Manifest.permission.WRITE_EXTERNAL_STORAGE)
                    == PackageManager.PERMISSION_GRANTED ) )
        {
            Log.v(TAG,"Permission is granted");
        } else {
            Log.v(TAG, "Permission is revoked");
            //ActivityCompat.requestPermissions(this, new String[]{android.Manifest.permission.CAMERA}, 1);
            ActivityCompat.requestPermissions(this, new String[]{
                    android.Manifest.permission.CAMERA,
                    android.Manifest.permission.RECORD_AUDIO,
                    android.Manifest.permission.WRITE_EXTERNAL_STORAGE  }, 1);
        }
    }

    mCamera = CameraHelper.getDefaultCameraInstance();
    if( mCamera == null )
    {
        return false;
    }
    // We need to make sure that our preview and recording video size are supported by the
    // camera. Query camera to find all the sizes and choose the optimal size given the
    // dimensions of our preview surface.
    Camera.Parameters parameters = mCamera.getParameters();
    List<Camera.Size> mSupportedPreviewSizes = parameters.getSupportedPreviewSizes();
    List<Camera.Size> mSupportedVideoSizes = parameters.getSupportedVideoSizes();

    int rotationCorrected = correctCameraRotation();
    parameters.setRotation( rotationCorrected );

    Camera.Size optimalSize = CameraHelper.getOptimalVideoSize(mSupportedVideoSizes,
            mSupportedPreviewSizes, mPreview.getWidth(), mPreview.getHeight());

    // Use the same size for recording profile.
    parameters.setPreviewSize( optimalSize.width, optimalSize.height);
    mCamera.setParameters(parameters);
    try {
        // Requires API level 11+, For backward compatibility use {@link setPreviewDisplay}
        // with {@link SurfaceView}
        mCamera.setPreviewTexture(mPreview.getSurfaceTexture());
    } catch (IOException e) {
        Log.e(TAG, "Surface texture is unavailable or unsuitable" + e.getMessage());
        return false;
    }
    // Step 1: Unlock and set camera to MediaRecorder
    mMediaRecorder = new MediaRecorder();
    try
    {
        mCamera.unlock();
        try {
            mMediaRecorder.setCamera(mCamera);
        }catch( Exception ex )
        {
            Log.e(TAG, "I don't know what happened... " + ex.getMessage());
        }
        // Step 2: Set sources            mMediaRecorder.setAudioSource(MediaRecorder.AudioSource.DEFAULT );
        mMediaRecorder.setVideoSource(MediaRecorder.VideoSource.CAMERA);

        CamcorderProfile profile = CamcorderProfile.get(CamcorderProfile.QUALITY_480P);
        profile.videoFrameWidth = optimalSize.width;
        profile.videoFrameHeight = optimalSize.height;
        profile.fileFormat = MediaRecorder.OutputFormat.MPEG_4;
        profile.videoCodec = MediaRecorder.VideoEncoder.MPEG_4_SP;
        profile.videoFrameRate = 24;
        // reduce audio quality
        profile.audioBitRate = 16000;
        profile.audioChannels = 1;

        // Step 3: Set a CamcorderProfile (requires API Level 8 or higher)
        /*  This method should be called after the video AND audio sources
        are set, and before setOutputFile()  */
        mMediaRecorder.setProfile(profile);

        mMediaRecorder.setOrientationHint( rotationCorrected );

        // Step 4: Set output file
        mOutputFile = CameraHelper.getOutputMediaFile(CameraHelper.MEDIA_TYPE_VIDEO);
        if (mOutputFile == null) {
            return false;
        }
        mMediaRecorder.setOutputFile(mOutputFile.getPath());
        // END_INCLUDE (configure_media_recorder)
    }
    catch( IllegalStateException ex )
    {
        Log.e(TAG, "IllegalStateException preparing MediaRecorder: " + ex.getMessage());
        return false;
    }
    catch( Exception ex )
    {
        Log.e(TAG, "I don't know what happened... " + ex.getMessage());
        return false;
    }
    // more stuff here
}

所以，当我尝试将输出格式更改为 webm 时，我得到了这个

        CamcorderProfile profile = CamcorderProfile.get(CamcorderProfile.QUALITY_480P);
        profile.videoFrameWidth = optimalSize.width;
        profile.videoFrameHeight = optimalSize.height;
        // FIXME mp4 to webm
        profile.fileFormat = MediaRecorder.OutputFormat.WEBM;
        profile.videoCodec = MediaRecorder.VideoEncoder.VP8;
        profile.audioCodec = MediaRecorder.AudioEncoder.AMR_NB;
        //profile.videoFrameRate = 24;
        // reduce audio quality
        //profile.audioBitRate = 16000;
        //profile.audioChannels = 1;


        // Step 3: Set a CamcorderProfile (requires API Level 8 or higher)
        /*  This method should be called after the video AND audio sources
        are set, and before setOutputFile()  */
        mMediaRecorder.setProfile(profile);

并且 setProfile 方法抛出一个 IllegalStateException，上面写着 E/MediaRecorder: output format (9) is meant for audio recording only and incompatible with video recording。谷歌搜索这条消息我到达这里:

• https://android.googlesource.com/platform/frameworks/av/+/114819633470ebd5b346c13c2a82a0025d2d39c0/media/libmedia/mediarecorder.cpp
• https://android.googlesource.com/platform/frameworks/av/+/114819633470ebd5b346c13c2a82a0025d2d39c0/include/media/mediarecorder.h

所以，我的问题是我的 profile.fileFormat = MediaRecorder.OutputFormat.WEBM 触发了这个

    if (mIsVideoSourceSet
        && of >= OUTPUT_FORMAT_AUDIO_ONLY_START //first non-video output format
        && of < OUTPUT_FORMAT_AUDIO_ONLY_END) {
    ALOGE("output format (%d) is meant for audio recording only"
          " and incompatible with video recording", of);
    return INVALID_OPERATION;
}

查看 OUTPUT_FORMAT_AUDIO_ONLY_START 和 OUTPUT_FORMAT_AUDIO_ONLY_END 值，我可以看到 OUTPUT_FORMAT_AUDIO_ONLY_END 应该是 9，在 MediaRecorder.java 中，Webm 格式是

/** WEBM 容器中的 VP8/VORBIS 数据 */
public static final int WEBM = 9;

如何将视频直接录制到 webm？

Answer 1

嗯，看来是Android SDK版本的问题。

IllegalStateException 出现在带有 SDK 17 的设备上。在带有 SDK 23 的设备上运行相同的应用程序工作正常，我可以录制 webm 视频。

但是没有声音:(