点击以使用 javacv 在 vi​​ne 中记录

Question

我正在尝试实现一个点击来记录功能，比如在 vine 中。 javacv 中提供的处理记录（非触摸记录）的示例是https://github.com/bytedeco/javacv/blob/master/samples/RecordActivity.java。我正在尝试对其进行修改，以便在 onPreviewFrame 方法中，仅当用户将手指放在屏幕上时才会将帧添加到缓冲区中。然后尝试在 stopRecording 方法中将这些帧组合成最终视频。

问题是，如果我按照下面的代码 sn-p（在 stopRecording 方法中）中给出的时间戳设置

if (t > recorder.getTimestamp()) 
{
    recorder.setTimestamp(t);
}

行为如下

案例 1

如果我点按屏幕录制 2 秒，然后将手指从屏幕上移开 3 秒，然后再次将手指放回屏幕上再录制 4 秒，结果视频是这样的，

第一个 2 秒视频已录制内容。接下来的 3 秒（手指离开屏幕的时间）。视频仅显示手指最后放在屏幕上时录制的最后一帧。然后视频已经录制了接下来 4 秒的视频内容。因此，当手指从屏幕上移开时，处理视频录制似乎存在问题。

案例 2

接下来我在 stopRecording 方法中删除了记录器的代码设置时间戳（上面给出的代码 sn-p）。

现在生成的视频（与案例 1 中尝试的相同步骤）不包含手指离开屏幕时的中间 3 秒（这是必需的）。但是视频播放速度更快。所以看来我们需要设置时间戳，以便视频以正常速率播放。

我的活动的完整代码如下。 （请注意，视频录制主要由 onPreviewFrame 和 stopRecording 方法处理）

public class TouchToRecordActivity extends Activity implements OnClickListener, View.OnTouchListener {

private final static String CLASS_LABEL = "TouchToRecordActivity";
private final static String LOG_TAG = CLASS_LABEL;

private String ffmpeg_link = "/mnt/sdcard/stream.mp4";

long startTime = 0;
boolean recording = false;
boolean rec = false;

private FFmpegFrameRecorder recorder;

private boolean isPreviewOn = false;

private int sampleAudioRateInHz = 44100;
private int imageWidth = 640;
private int imageHeight = 480;
private int destWidth = 480;
private int frameRate = 30;

/* audio data getting thread */
private AudioRecord audioRecord;
private AudioRecordRunnable audioRecordRunnable;
private Thread audioThread;
volatile boolean runAudioThread = true;

/* video data getting thread */
private Camera cameraDevice;
private CameraView cameraView;

private Frame yuvImage = null;

/* layout setting */
private final int bg_screen_bx = 232;
private final int bg_screen_by = 128;
private final int bg_screen_width = 700;
private final int bg_screen_height = 500;
private final int bg_width = 1123;
private final int bg_height = 715;
private final int live_width = 640;
private final int live_height = 480;
private int screenWidth, screenHeight;
private Button btnRecorderControl;

/* The number of seconds in the continuous record loop (or 0 to disable loop). */
final int RECORD_LENGTH = 20;
Frame[] images;
long[] timestamps;
ShortBuffer[] samples;
int imagesIndex, samplesIndex;

long firstTime = 0;
long startPauseTime = 0;
long totalPauseTime = 0;
long pausedTime = 0;
long stopPauseTime = 0;
long totalTime = 0;

long totalRecordedTS = 0;

private TextView txtTimer;
private Handler mHandler = new Handler();

@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setRequestedOrientation(ActivityInfo.SCREEN_ORIENTATION_LANDSCAPE);

    setContentView(R.layout.touch_main);

    initLayout();
}

@Override
protected void onDestroy() {
    super.onDestroy();

    recording = false;

    if (cameraView != null) {
        cameraView.stopPreview();
    }

    if (cameraDevice != null) {
        cameraDevice.stopPreview();
        cameraDevice.release();
        cameraDevice = null;
    }
}


private void initLayout() {

    /* get size of screen */
    Display display = ((WindowManager) getSystemService(Context.WINDOW_SERVICE)).getDefaultDisplay();
    screenWidth = display.getWidth();
    screenHeight = display.getHeight();
    RelativeLayout.LayoutParams layoutParam = null;
    LayoutInflater myInflate = null;
    myInflate = (LayoutInflater) getSystemService(Context.LAYOUT_INFLATER_SERVICE);
    RelativeLayout topLayout = new RelativeLayout(this);
    setContentView(topLayout);
    LinearLayout preViewLayout = (LinearLayout) myInflate.inflate(R.layout.touch_main, null);
    layoutParam = new RelativeLayout.LayoutParams(screenWidth, screenHeight);
    topLayout.addView(preViewLayout, layoutParam);

    txtTimer = (TextView) preViewLayout.findViewById(R.id.txtTimer);

    /* add control button: start and stop */
    btnRecorderControl = (Button) findViewById(R.id.recorder_control);
    btnRecorderControl.setText("Start");
    btnRecorderControl.setOnClickListener(this);

    /* add camera view */
    int display_width_d = (int) (1.0 * bg_screen_width * screenWidth / bg_width);
    int display_height_d = (int) (1.0 * bg_screen_height * screenHeight / bg_height);
    int prev_rw, prev_rh;
    if (1.0 * display_width_d / display_height_d > 1.0 * live_width / live_height) {
        prev_rh = display_height_d;
        prev_rw = (int) (1.0 * display_height_d * live_width / live_height);
    } else {
        prev_rw = display_width_d;
        prev_rh = (int) (1.0 * display_width_d * live_height / live_width);
    }
    layoutParam = new RelativeLayout.LayoutParams(prev_rw, prev_rh);
    layoutParam.topMargin = (int) (1.0 * bg_screen_by * screenHeight / bg_height);
    layoutParam.leftMargin = (int) (1.0 * bg_screen_bx * screenWidth / bg_width);

    cameraDevice = Camera.open();
    Log.i(LOG_TAG, "cameara open");
    cameraView = new CameraView(this, cameraDevice);
    topLayout.addView(cameraView, layoutParam);
    topLayout.setOnTouchListener(this);
    Log.i(LOG_TAG, "cameara preview start: OK");
}

//---------------------------------------
// initialize ffmpeg_recorder
//---------------------------------------
private void initRecorder() {

    Log.w(LOG_TAG, "init recorder");

    if (RECORD_LENGTH > 0) {
        imagesIndex = 0;
        images = new Frame[RECORD_LENGTH * frameRate];
        timestamps = new long[images.length];
        for (int i = 0; i < images.length; i++) {
            images[i] = new Frame(destWidth, imageHeight, Frame.DEPTH_UBYTE, 2);
            timestamps[i] = -1;
        }
    } else if (yuvImage == null) {
        yuvImage = new Frame(destWidth, imageHeight, Frame.DEPTH_UBYTE, 2);
        Log.i(LOG_TAG, "create yuvImage");
    }
    Log.i(LOG_TAG, "ffmpeg_url: " + ffmpeg_link);
    recorder = new FFmpegFrameRecorder(ffmpeg_link, destWidth, imageHeight, 1);
    recorder.setFormat("mp4");
    recorder.setVideoCodecName("libx264");
    recorder.setSampleRate(sampleAudioRateInHz);
    // Set in the surface changed method
    recorder.setFrameRate(frameRate);

    Log.i(LOG_TAG, "recorder initialize success");

    audioRecordRunnable = new AudioRecordRunnable();
    audioThread = new Thread(audioRecordRunnable);
    runAudioThread = true;
}

public void startRecording() {

    initRecorder();

    mHandler.removeCallbacks(mUpdateTimeTask);
    mHandler.postDelayed(mUpdateTimeTask, 100);

    try {
        recorder.start();
        startTime = System.currentTimeMillis();
        recording = true;
        audioThread.start();

    } catch (FFmpegFrameRecorder.Exception e) {
        e.printStackTrace();
    }
}

public void stopRecording() {

    runAudioThread = false;
    try {
        audioThread.join();
    } catch (InterruptedException e) {
        e.printStackTrace();
    }
    audioRecordRunnable = null;
    audioThread = null;

    if (recorder != null && recording) {
        if (RECORD_LENGTH > 0) {
            Log.v(LOG_TAG, "Writing frames");
            try {
                int firstIndex = imagesIndex % samples.length;
                int lastIndex = (imagesIndex - 1) % images.length;
                if (imagesIndex <= images.length) {
                    firstIndex = 0;
                    lastIndex = imagesIndex - 1;
                }
                if ((startTime = timestamps[lastIndex] - RECORD_LENGTH * 1000000L) < 0) {
                    startTime = 0;
                }
                if (lastIndex < firstIndex) {
                    lastIndex += images.length;
                }
                int videoCounter = 0;
                for (int i = firstIndex; i <= lastIndex; i++) {
                    if (timestamps[i] == -1) {
                        Log.v(LOG_TAG, "frame not recorded");
                    }
                    if (timestamps[i] != -1) {
                        long t = timestamps[i % timestamps.length] - startTime;
                        if (t >= 0) {

                            videoCounter++;

                            /*if (((i % images.length) != 0) && images[i % images.length] != images[(i % images.length) - 1]) {
                                if (t > recorder.getTimestamp()) {
                                    recorder.setTimestamp(t);
                                }*/
                                Log.v(LOG_TAG, "imageIndex=" + (i % images.length));
                                recorder.record(images[i % images.length]);
                        /*    }*/
                            Log.v(LOG_TAG, "videoCounter=" + videoCounter);
                        }
                    }
                }

                firstIndex = samplesIndex % samples.length;
                lastIndex = (samplesIndex - 1) % samples.length;
                if (samplesIndex <= samples.length) {
                    firstIndex = 0;
                    lastIndex = samplesIndex - 1;
                }
                if (lastIndex < firstIndex) {
                    lastIndex += samples.length;
                }
                for (int i = firstIndex; i <= lastIndex; i++) {
                    if (timestamps[i] != -1) {
                        recorder.recordSamples(samples[i % samples.length]);
                    }
                }
            } catch (FFmpegFrameRecorder.Exception e) {
                Log.v(LOG_TAG, e.getMessage());
                e.printStackTrace();
            }
        }

        recording = false;
        Log.v(LOG_TAG, "Finishing recording, calling stop and release on recorder");
        try {
            recorder.stop();
            recorder.release();
        } catch (FFmpegFrameRecorder.Exception e) {
            e.printStackTrace();
        }
        recorder = null;

    }
}

@Override
public boolean onKeyDown(int keyCode, KeyEvent event) {

    if (keyCode == KeyEvent.KEYCODE_BACK) {
        if (recording) {
            stopRecording();
        }

        finish();

        return true;
    }

    return super.onKeyDown(keyCode, event);
}

@Override
public boolean onTouch(View view, MotionEvent motionEvent) {
    switch (motionEvent.getAction()) {
        case MotionEvent.ACTION_DOWN:
            Log.v(LOG_TAG, "ACTION_DOWN" + recording);

            if (!recording) {
                startRecording();
            } else {
                stopPauseTime = System.currentTimeMillis();
                totalPauseTime = stopPauseTime - startPauseTime - ((long) (1.0 / (double) frameRate) * 1000);
                pausedTime += totalPauseTime;
            }
            rec = true;
            setTotalVideoTime();
            btnRecorderControl.setText(getResources().getString(R.string.stop));
            break;
        case MotionEvent.ACTION_MOVE:
            rec = true;
            setTotalVideoTime();
            break;
        case MotionEvent.ACTION_UP:
            Log.v(LOG_TAG, "ACTION_UP");
            rec = false;
            startPauseTime = System.currentTimeMillis();
            break;
    }
    return true;
}

private Runnable mUpdateTimeTask = new Runnable() {
    public void run() {
        if (recording) {
            setTotalVideoTime();
        }
        mHandler.postDelayed(this, 500);
    }
};

private synchronized void setTotalVideoTime() {
    totalTime = System.currentTimeMillis() - firstTime - pausedTime - ((long) (1.0 / (double) frameRate) * 1000);
    if (totalTime > 0)
        txtTimer.setText(getRecordingTimeFromMillis(totalTime));
}

private String getRecordingTimeFromMillis(long millis) {
    String strRecordingTime = null;
    int seconds = (int) (millis / 1000);
    int minutes = seconds / 60;
    int hours = minutes / 60;

    if (hours >= 0 && hours < 10)
        strRecordingTime = "0" + hours + ":";
    else
        strRecordingTime = hours + ":";

    if (hours > 0)
        minutes = minutes % 60;

    if (minutes >= 0 && minutes < 10)
        strRecordingTime += "0" + minutes + ":";
    else
        strRecordingTime += minutes + ":";

    seconds = seconds % 60;

    if (seconds >= 0 && seconds < 10)
        strRecordingTime += "0" + seconds;
    else
        strRecordingTime += seconds;

    return strRecordingTime;

}


//---------------------------------------------
// audio thread, gets and encodes audio data
//---------------------------------------------
class AudioRecordRunnable implements Runnable {

    @Override
    public void run() {
        android.os.Process.setThreadPriority(android.os.Process.THREAD_PRIORITY_URGENT_AUDIO);

        // Audio
        int bufferSize;
        ShortBuffer audioData;
        int bufferReadResult;

        bufferSize = AudioRecord.getMinBufferSize(sampleAudioRateInHz,
                AudioFormat.CHANNEL_IN_MONO, AudioFormat.ENCODING_PCM_16BIT);
        audioRecord = new AudioRecord(MediaRecorder.AudioSource.MIC, sampleAudioRateInHz,
                AudioFormat.CHANNEL_IN_MONO, AudioFormat.ENCODING_PCM_16BIT, bufferSize);

        if (RECORD_LENGTH > 0) {
            samplesIndex = 0;
            samples = new ShortBuffer[RECORD_LENGTH * sampleAudioRateInHz * 2 / bufferSize + 1];
            for (int i = 0; i < samples.length; i++) {
                samples[i] = ShortBuffer.allocate(bufferSize);
            }
        } else {
            audioData = ShortBuffer.allocate(bufferSize);
        }

        Log.d(LOG_TAG, "audioRecord.startRecording()");
        audioRecord.startRecording();

        /* ffmpeg_audio encoding loop */
        while (runAudioThread) {
            if (RECORD_LENGTH > 0) {
                audioData = samples[samplesIndex++ % samples.length];
                audioData.position(0).limit(0);
            }
            //Log.v(LOG_TAG,"recording? " + recording);
            bufferReadResult = audioRecord.read(audioData.array(), 0, audioData.capacity());
            audioData.limit(bufferReadResult);
            if (bufferReadResult > 0) {
                Log.v(LOG_TAG, "bufferReadResult: " + bufferReadResult);
                // If "recording" isn't true when start this thread, it never get's set according to this if statement...!!!
                // Why?  Good question...
                if (recording && rec) {
                    Log.v(LOG_TAG, "Recording audio");
                    if (RECORD_LENGTH <= 0) try {
                        recorder.recordSamples(audioData);
                        //Log.v(LOG_TAG,"recording " + 1024*i + " to " + 1024*i+1024);
                    } catch (FFmpegFrameRecorder.Exception e) {
                        Log.v(LOG_TAG, e.getMessage());
                        e.printStackTrace();
                    }
                }
            }
        }
        Log.v(LOG_TAG, "AudioThread Finished, release audioRecord");

        /* encoding finish, release recorder */
        if (audioRecord != null) {
            audioRecord.stop();
            audioRecord.release();
            audioRecord = null;
            Log.v(LOG_TAG, "audioRecord released");
        }
    }
}

//---------------------------------------------
// camera thread, gets and encodes video data
//---------------------------------------------
class CameraView extends SurfaceView implements SurfaceHolder.Callback, PreviewCallback {

    private SurfaceHolder mHolder;
    private Camera mCamera;

    public CameraView(Context context, Camera camera) {
        super(context);
        Log.w("camera", "camera view");
        mCamera = camera;
        mHolder = getHolder();
        mHolder.addCallback(CameraView.this);
        mHolder.setType(SurfaceHolder.SURFACE_TYPE_PUSH_BUFFERS);
        mCamera.setPreviewCallback(CameraView.this);
    }

    @Override
    public void surfaceCreated(SurfaceHolder holder) {
        try {
            stopPreview();
            mCamera.setPreviewDisplay(holder);
        } catch (IOException exception) {
            mCamera.release();
            mCamera = null;
        }
    }

    public void surfaceChanged(SurfaceHolder holder, int format, int width, int height) {
        stopPreview();

        Camera.Parameters camParams = mCamera.getParameters();
        List<Camera.Size> sizes = camParams.getSupportedPreviewSizes();
        // Sort the list in ascending order
        Collections.sort(sizes, new Comparator<Camera.Size>() {

            public int compare(final Camera.Size a, final Camera.Size b) {
                return a.width * a.height - b.width * b.height;
            }
        });

        camParams.setPreviewSize(imageWidth, imageHeight);

        Log.v(LOG_TAG, "Setting imageWidth: " + imageWidth + " imageHeight: " + imageHeight + " frameRate: " + frameRate);

        camParams.setPreviewFrameRate(frameRate);
        Log.v(LOG_TAG, "Preview Framerate: " + camParams.getPreviewFrameRate());

        mCamera.setParameters(camParams);

        List<Camera.Size> videoSizes = mCamera.getParameters().getSupportedVideoSizes();

        // Set the holder (which might have changed) again
        try {
            mCamera.setPreviewDisplay(holder);
            mCamera.setPreviewCallback(CameraView.this);
            startPreview();
        } catch (Exception e) {
            Log.e(LOG_TAG, "Could not set preview display in surfaceChanged");
        }
    }

    @Override
    public void surfaceDestroyed(SurfaceHolder holder) {
        try {
            mHolder.addCallback(null);
            mCamera.setPreviewCallback(null);
        } catch (RuntimeException e) {
            // The camera has probably just been released, ignore.
        }
    }

    public void startPreview() {
        if (!isPreviewOn && mCamera != null) {
            isPreviewOn = true;
            mCamera.startPreview();
        }
    }

    public void stopPreview() {
        if (isPreviewOn && mCamera != null) {
            isPreviewOn = false;
            mCamera.stopPreview();
        }
    }

    @Override
    public void onPreviewFrame(byte[] data, Camera camera) {
        if (audioRecord == null || audioRecord.getRecordingState() != AudioRecord.RECORDSTATE_RECORDING) {
            startTime = System.currentTimeMillis();
            return;
        }
        if (RECORD_LENGTH > 0) {
            int i = imagesIndex++ % images.length;
            Log.v(LOG_TAG, "recording:" + recording + "rec:" + rec);
            if (recording && rec) {
                yuvImage = images[i];
                timestamps[i] = 1000 * (System.currentTimeMillis() - startTime);
                totalRecordedTS++;
            } else {
                Log.v(LOG_TAG, "recording is paused");
                yuvImage = null;
                timestamps[i] = -1;
            }
        }

        /* get video data */
        if (yuvImage != null && recording && rec) {
            if (data.length != imageWidth * imageHeight) {
                Camera.Size sz = camera.getParameters().getPreviewSize();
                imageWidth = sz.width;
                imageHeight = sz.height;
                destWidth = imageHeight;
                Log.v(LOG_TAG, "data length:" + data.length);
            }

            ByteBuffer bb = (ByteBuffer) yuvImage.image[0].position(0); // resets the buffer
            int start = 2 * ((imageWidth - destWidth) / 4); // this must be even
            for (int row = 0; row < imageHeight * 3 / 2; row++) {
                bb.put(data, start, destWidth);
                start += imageWidth;
            }

        }
    }
}

@Override
public void onClick(View v) {
    if (!recording) {
        startRecording();
        Log.w(LOG_TAG, "Start Button Pushed");
        btnRecorderControl.setText("Stop");
    } else {
        // This will trigger the audio recording loop to stop and then set isRecorderStart = false;
        stopRecording();
        Log.w(LOG_TAG, "Stop Button Pushed");
        btnRecorderControl.setText("Start");
    }
}}

根据 Alex Cohn 的建议进行的更改

建议 1 - 估计平均帧速率

    public void stopRecording() {

   ..............................

                            if (((i % images.length) != 0) && images[i % images.length] != images[(i % images.length) - 1]) {
                                if (t > recorder.getTimestamp()) {
                                    t += 1000000 / frameRate;
                                    recorder.setTimestamp(t);
                                }

                                recorder.record(images[i % images.length]);
                            }
             ..........................................


}

所做的更改是添加 t += 1000000 / frameRate;但这会导致视频在手指远离屏幕时部分冻结（如上述情况 1）。

建议 2 - onPreviewFrame() 中的修改

long[] timestampsForRecorder;
private void initRecorder() {

    Log.w(LOG_TAG, "init recorder");

    if (RECORD_LENGTH > 0) {
       .......................................................
        timestampsForRecorder = new long[images.length];
        for (int i = 0; i < images.length; i++) {
            images[i] = new Frame(destWidth, imageHeight, Frame.DEPTH_UBYTE, 2);
            timestamps[i] = -1;
            timestampsForRecorder[i] = -1;
        }
    } else if (yuvImage == null) {
        yuvImage = new Frame(destWidth, imageHeight, Frame.DEPTH_UBYTE, 2);
        Log.i(LOG_TAG, "create yuvImage");
    }
    ...................................................
}

@Override
public void onPreviewFrame(byte[] data, Camera camera) {
        if (audioRecord == null || audioRecord.getRecordingState() != AudioRecord.RECORDSTATE_RECORDING) {
            startTime = SystemClock.elapsedRealtime();
            return;
        }
        if (RECORD_LENGTH > 0) {
            int i = imagesIndex++ % images.length;
            Log.v(LOG_TAG, "recording:" + recording + "rec:" + rec);
            if (recording && rec) {
                yuvImage = images[i];
                long thisFrameTime = SystemClock.elapsedRealtime();
                timestamps[i] = thisFrameTime;
                long lastFrameTime = timestamps[(int) (imagesIndex == 0 ? startTime : ((imagesIndex-1) % images.length))];
                Log.v(LOG_TAG, "lastFrameTime:" + lastFrameTime+",stopPauseTime:" + stopPauseTime);
                if (lastFrameTime > stopPauseTime) {
                    timestampsForRecorder[i] = 1000 * (thisFrameTime - Math.max(stopPauseTime, lastFrameTime));
                }
            }
        }

       .....................................................
    }

public void stopRecording() {

    .......................................................

    if (recorder != null && recording) {
        if (RECORD_LENGTH > 0) {
            Log.v(LOG_TAG, "Writing frames");
            try {
                int firstIndex = imagesIndex % samples.length;
                int lastIndex = (imagesIndex - 1) % images.length;
                if (imagesIndex <= images.length) {
                    firstIndex = 0;
                    lastIndex = imagesIndex - 1;
                }
                if ((startTime = timestampsForRecorder[lastIndex] - RECORD_LENGTH * 1000000L) < 0) {
                    startTime = 0;
                }
                if (lastIndex < firstIndex) {
                    lastIndex += images.length;
                }
                for (int i = firstIndex; i <= lastIndex; i++) {

                    if (timestampsForRecorder[i] != -1) {
                        long t = timestampsForRecorder[i % timestampsForRecorder.length] - startTime;
                        if (t >= 0) {

                            if (((i % images.length) != 0) && images[i % images.length] != images[(i % images.length) - 1]) {
                                if (t > recorder.getTimestamp()) {
                                    recorder.setTimestamp(t);
                                }
                                Log.v(LOG_TAG, "imageIndex=" + (i % images.length));
                                recorder.record(images[i % images.length]);
                            }
                        }
                    }
                }
                .............................................
            } catch (FFmpegFrameRecorder.Exception e) {
               .................................
            }
        }

        ...........................................

    }
}

使用此方法录制的视频存在上述案例 2 中的问题。即，它正在以更快的速度播放

Answer 1

简单（但不精确）的解决方案是估计平均帧速率，并使用t += 1000000/average_fps; recorder.setTimestamp(t); 而不是查看实际时间戳。

为了更准确，您可以将onPreviewFrame()更改如下：

long thisFrameTime = SystemClock.elapsedRealtime();
timestamps[i] = thisFrameTime;
long lastFrameTime = timestamps[imagesIndex < 2 ? startTime : (imagesIndex-2) % images.length)];
if (lastFrameTime > stopPauseTime) {
    timestampsForRecorder[i] = 1000 * (thisFrameTime - Math.max(stopPauseTime, lastFrameTime));
}

您可以将第二个数组 timestampsForRecorder 直接提供给记录器。

请注意，在任何地方使用SystemClock.elapsedRealtime() 会更安全：

此时钟保证是单调的，即使在 CPU 处于省电模式时也会继续计时，因此是通用间隔计时的推荐依据。