本文主要是介绍Android 播放视频并获取指定时间的帧画面,希望对大家解决编程问题提供一定的参考价值,需要的开发者们随着小编来一起学习吧!
Android 播放视频并获取指定时间的帧画面
最近做的项目要求既能播放视频(类似于视频播放器),又能每隔1s左右获取一帧视频画面,然后对图片进行处理,调查了一周,也被折磨了一周,总算找到了大致符合要求的方法。首先对调查过程中涉及到的方法进行简单介绍,再重点介绍最终所采用的方法,话不多说,进入正题。
一.MediaMetadataRetriever
播放视频并取得画面的一帧,大家最先想到应该都是这个,我同样也最先对它进行了测试,这里使用MediaPlayer进行播放,视频播放界面使用SurfaceView来实现。
public class PlayerMainActivity extends Activity implements OnClickListener,SurfaceHolder.Callback, Runnable {private static final String TAG = "Movie";private MediaPlayer mediaPlayer;private SurfaceView surfaceView;private SurfaceHolder surfaceHolder;private Button play_btn;private int currentPosition = 0;private Bitmap bitmap = null;private String dataPath = Environment.getExternalStorageDirectory() + "/Video/Test_movie.AVI";@Overrideprotected void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.activity_main);surfaceView = (SurfaceView) findViewById(R.id.surfaceView);play_btn = (Button) findViewById(R.id.play_btn); play_btn.setOnClickListener(this);screen_cut_btn.setOnClickListener(this); surfaceHolder = surfaceView.getHolder();surfaceHolder.addCallback(this);}@Overridepublic void run() {mediaPlayer = new MediaPlayer();mediaPlayer.setAudioStreamType(AudioManager.STREAM_MUSIC);mediaPlayer.setDisplay(surfaceHolder);try {mediaPlayer.setDataSource(dataPath);mediaPlayer.prepare(); MediaMetadataRetriever mediaMetadataRetriever = new MediaMetadataRetriever();mediaMetadataRetriever.setDataSource(dataPath);int millis = mediaPlayer.getDuration();Log.i(TAG, "millis: " + millis/1000);for (int i = 10000*1000; i < 20*1000*1000; i+=500*1000) {bitmap = mediaMetadataRetriever.getFrameAtTime(i, MediaMetadataRetriever.OPTION_CLOSEST);String path = Environment.getExternalStorageDirectory() + "/bitmap/" + i + ".png";FileOutputStream fileOutputStream = null;try {fileOutputStream = new FileOutputStream(path);bitmap.compress(CompressFormat.PNG, 100, fileOutputStream);Log.i(TAG, "i: " + i/1000/1000);} catch (Exception e) {Log.i(TAG, "Error: " + i/1000/1000);e.printStackTrace();}finally {if (fileOutputStream != null) {fileOutputStream.close();}} bitmap.recycle();}} catch (Exception e) {e.printStackTrace();}}@Overridepublic void surfaceCreated(SurfaceHolder holder) {Thread t = new Thread(this);t.start();}@Overridepublic void surfaceChanged(SurfaceHolder holder, int format, int width, int height) {}@Overridepublic void surfaceDestroyed(SurfaceHolder holder) {}@Overridepublic void onClick(View view) {switch (view.getId()) {case R.id.play_btn:if (mediaPlayer.isPlaying()) {mediaPlayer.pause();play_btn.setText(getResources().getText(R.string.play));} else {mediaPlayer.start();play_btn.setText(getResources().getText(R.string.pause));}break;default:break;}}@Overrideprotected void onDestroy() {super.onDestroy();if (mediaPlayer.isPlaying()) {mediaPlayer.stop();}mediaPlayer.release();} }
获取一帧的关键代码为:
Bitmap bitmap = mediaMetadataRetriever.getFrameAtTime(timeMs * 1000, MediaMetadataRetriever.OPTION_CLOSEST);
public Bitmap getFrameAtTime(long timeUs, int option)
第一个参数是传入时间,只能是us(微秒)
第二个参数:
- OPTION_CLOSEST 在给定的时间,检索最近一个帧,这个帧不一定是关键帧。
- OPTION_CLOSEST_SYNC 在给定的时间,检索最近一个同步与数据源相关联的的帧(关键帧)。
- OPTION_NEXT_SYNC 在给定时间之后检索一个同步与数据源相关联的关键帧。
- OPTION_PREVIOUS_SYNC 顾名思义,同上
这里为了提取我们想要的帧,不使用关键帧,所以用 OPTION_CLOSEST .
最终的测试结果并不理想,连续取20帧画面,其中真正有效的只有7张,其余都是重复的,原因为即使是使用参数OPTION_CLOSEST,程序仍然会去取指定时间临近的关键帧,如10s-15s总是取同一帧,因此这种方法不可用。
提高视频的质量或许有效,未尝试。
补充MediaMetadataRetriever的其他知识
// 取得视频的总长度(单位为毫秒)
String time = mediaMetadataRetriever. extractMetadata( MediaMetadataRetriever. METADATA_KEY_DURATION);
MediaMetadataRetriever主要用来取缩略图。
二.ThumbnailUtils
同样主要是用来获取视频的缩略图,不可靠,因此并未深入研究。
从以上两种方法可以看出,Android API 所提供的获取视频帧的方法大都只能获取视频的缩略图,没办法获取视频每一帧的图片。因此,调查方向应当转向对视频进行解码,然后获取任意一帧。
三.MediaCodec
硬件解码,尝试从inputBuffers、outputBuffers中获取帧画面,失败,bitmap中的数据大小始终为0 KB。
public class MoviePlayerActivity extends Activity implements OnTouchListener, OnClickListener, SurfaceHolder.Callback {private static final String TAG = "Image";private String file_path;private Button movie_play;private boolean playButtonVisible;private boolean playPause;private SurfaceView surfaceView;private SurfaceHolder surfaceHolder;private PlayerThread playerThread = null;private ByteBuffer mPixelBuf;@Overrideprotected void onCreate(Bundle savedInstanceState) {getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN, WindowManager.LayoutParams.FLAG_FULLSCREEN); requestWindowFeature(Window.FEATURE_NO_TITLE); setRequestedOrientation(ActivityInfo.SCREEN_ORIENTATION_LANDSCAPE);super.onCreate(savedInstanceState);setContentView(R.layout.movie_player_activity);movie_play = (Button) findViewById(R.id.movie_videoview_play);movie_play.setOnClickListener(this);movie_play.setText("Play");Intent intent = getIntent();file_path = intent.getStringExtra("file_path"); //此Activity是从其他页面跳转来的,file_path为要播放的视频地址surfaceView = (SurfaceView) findViewById(R.id.surfaceView);surfaceHolder = surfaceView.getHolder();surfaceHolder.addCallback(this);mPixelBuf = ByteBuffer.allocateDirect(640*480*4);mPixelBuf.order(ByteOrder.LITTLE_ENDIAN);}@Overridepublic void surfaceCreated(SurfaceHolder holder) {if (playerThread == null) {playerThread = new PlayerThread(holder.getSurface());playerThread.start();}}@Overridepublic void surfaceChanged(SurfaceHolder holder, int format, int width, int height) { }@Overridepublic void surfaceDestroyed(SurfaceHolder holder) {if (playerThread != null) {playerThread.interrupt();}} @Overridepublic boolean onTouch(View v, MotionEvent event) {if (!playButtonVisible) {movie_play.setVisibility(View.VISIBLE);movie_play.setEnabled(true);} else {movie_play.setVisibility(View.INVISIBLE);}playButtonVisible = !playButtonVisible;return false;}@Overridepublic void onClick(View view) {switch (view.getId()) {case R.id.movie_videoview_play:if (!playPause) {movie_play.setText("Pause");} else {movie_play.setText("Play");}playPause = !playPause;break;default:break;}}private void writeFrameToSDCard(byte[] bytes, int i, int sampleSize) { i++;if (i%10 == 0) {try {Bitmap bmp = BitmapFactory.decodeByteArray(bytes, 0, sampleSize);mPixelBuf.rewind();bmp.copyPixelsFromBuffer(mPixelBuf);String path = Environment.getExternalStorageDirectory() + "/bitmap/" + i + ".png";FileOutputStream fileOutputStream = null;try {fileOutputStream = new FileOutputStream(path);bmp.compress(CompressFormat.PNG, 90, fileOutputStream);bmp.recycle();Log.i(TAG, "i: " + i);} catch (Exception e) {Log.i(TAG, "Error: " + i);e.printStackTrace();}finally {if (fileOutputStream != null) {fileOutputStream.close();}}} catch (Exception e) {e.printStackTrace();}}}private class PlayerThread extends Thread {private MediaExtractor extractor;private MediaCodec mediaCodec;private Surface surface;public PlayerThread(Surface surface) {this.surface = surface;}@Overridepublic void run() {extractor = new MediaExtractor();try {extractor.setDataSource(file_path);} catch (IOException e1) {Log.i(TAG, "Error");e1.printStackTrace();}for (int i = 0; i < extractor.getTrackCount(); i++) {MediaFormat format = extractor.getTrackFormat(i);String mime = format.getString(MediaFormat.KEY_MIME);if (mime.startsWith("video/")) {extractor.selectTrack(i);mediaCodec = MediaCodec.createDecoderByType(mime);mediaCodec.configure(format, surface, null, 0);break;}}if (mediaCodec == null) {Log.e(TAG, "Can't find video info!");return;}mediaCodec.start();ByteBuffer[] inputBuffers = mediaCodec.getInputBuffers();ByteBuffer[] outputBuffers = mediaCodec.getOutputBuffers();BufferInfo info = new BufferInfo();boolean isEOS = false;long startMs = System.currentTimeMillis();int i = 0;while (!Thread.interrupted()) {if (!isEOS) {int inIndex = mediaCodec.dequeueInputBuffer(10000);if (inIndex >= 0) {ByteBuffer buffer = inputBuffers[inIndex];int sampleSize = extractor.readSampleData(buffer, 0);if (sampleSize < 0) {// We shouldn't stop the playback at this point, just pass the EOS// flag to mediaCodec, we will get it again from the dequeueOutputBufferLog.d(TAG, "InputBuffer BUFFER_FLAG_END_OF_STREAM");mediaCodec.queueInputBuffer(inIndex, 0, 0, 0, MediaCodec.BUFFER_FLAG_END_OF_STREAM);isEOS = true;} else {mediaCodec.queueInputBuffer(inIndex, 0, sampleSize, extractor.getSampleTime(), 0);extractor.advance();}}}int outIndex = mediaCodec.dequeueOutputBuffer(info, 100000);switch (outIndex) {case MediaCodec.INFO_OUTPUT_BUFFERS_CHANGED:Log.d(TAG, "INFO_OUTPUT_BUFFERS_CHANGED");outputBuffers = mediaCodec.getOutputBuffers();break;case MediaCodec.INFO_OUTPUT_FORMAT_CHANGED:Log.d(TAG,"New format " + mediaCodec.getOutputFormat());break;case MediaCodec.INFO_TRY_AGAIN_LATER:Log.d(TAG, "dequeueOutputBuffer timed out!");break;default:ByteBuffer buffer = outputBuffers[outIndex];Log.v(TAG,"We can't use this buffer but render it due to the API limit, " + buffer);// We use a very simple clock to keep the video FPS, or the video// playback will be too fastwhile (info.presentationTimeUs / 1000 > System.currentTimeMillis() - startMs) {try {sleep(10);} catch (InterruptedException e) {e.printStackTrace();break;}}mediaCodec.releaseOutputBuffer(outIndex, true);/* saves frame to SDcard */mPixelBuf.rewind();GLES20.glReadPixels(0, 0, 640, 480, GLES20.GL_RGBA, GLES20.GL_UNSIGNED_BYTE, mPixelBuf);try {ByteBuffer outByteBuffer = outputBuffers[outIndex];outByteBuffer.position(info.offset); outByteBuffer.limit(info.offset + info.size); //info的两个参数值始终为0,所保存的.png也都是0KB。outByteBuffer.limit(2);byte[] dst = new byte[outByteBuffer.capacity()];outByteBuffer.get(dst);writeFrameToSDCard(dst, i, dst.length); i++;} catch (Exception e) {Log.d(TAG, "Error while creating bitmap with: " + e.getMessage());}break;}// All decoded frames have been rendered, we can stop playing nowif ((info.flags & MediaCodec.BUFFER_FLAG_END_OF_STREAM) != 0) {Log.d(TAG, "OutputBuffer BUFFER_FLAG_END_OF_STREAM");break;}}mediaCodec.stop();mediaCodec.release();extractor.release();}} }
所保存的图片大小始终为0的原因大概和下面的方法五类似。
想要深入研究此方法可以参考:
http://stackoverflow.com/questions/19754547/mediacodec-get-all-frames-from-video
http://stackoverflow.com/questions/23321880/how-to-get-bitmap-frames-from-video-using-mediacodec
四.JCodec
http://jcodec.org/
jcodec-samples-0.1.7.apk
解码视频文件耗时较长,性能较差,平均1.5s取一帧图片,达不到要求。
五.使用VideoView播放视频,使用getDrawingCache获取View视图
VideoView是Android提供的播放视频组件,上手很容易。这里使用getDrawingCache获取控件的View。
但是DrawingCache只能截取非视频部分的画面,播放视频的那个小窗口一直是黑色的。原因为Activity画面走的是framebuffer,视频是硬解码推送过来的,所有读取/dev/graphics/fb0 视频播放的那一块就是黑色的,硬件解码不会推送到buffer的,而是直接推送到硬件输出了。
public class MoviePlayerActivity extends Activity implements OnTouchListener, OnClickListener, Runnable {private static final String TAG = "Image";private String file_path;private VideoView videoView;private Button movie_play;private boolean playButtonVisible;private boolean playPause;@Overrideprotected void onCreate(Bundle savedInstanceState) {// full screen getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN, WindowManager.LayoutParams.FLAG_FULLSCREEN);// no title requestWindowFeature(Window.FEATURE_NO_TITLE);// landscape or horizontal screen setRequestedOrientation(ActivityInfo.SCREEN_ORIENTATION_LANDSCAPE);super.onCreate(savedInstanceState);setContentView(R.layout.movie_player_activity);movie_play = (Button) findViewById(R.id.movie_videoview_play);movie_play.setOnClickListener(this);movie_play.setText("Play");Intent intent = getIntent();file_path = intent.getStringExtra("file_path");videoView = (VideoView) findViewById(R.id.movie_palyer_videoview);videoView.setMediaController(null);// videoView.setMediaController(new MediaController(this)); videoView.setVideoPath(file_path);videoView.start();videoView.requestFocus();Thread screenShootThread = new Thread(this);screenShootThread.start();videoView.setOnTouchListener(this);}@Overridepublic void run() { //播放视频时后台自动截图,注意参数为videoViewfor (int i = 10000 * 1000; i < 20 * 1000 * 1000; i += 500 * 1000) {int nowTime = videoView.getCurrentPosition();try {screenShot(videoView, i);} catch (Exception e1) {Log.i(TAG, "Error: screenShot. ");e1.printStackTrace();}try {Thread.sleep(500);} catch (InterruptedException e) {e.printStackTrace();}}}@Overridepublic boolean onTouch(View v, MotionEvent event) {if (!playButtonVisible) {movie_play.setVisibility(View.VISIBLE);movie_play.setEnabled(true);} else {movie_play.setVisibility(View.INVISIBLE);}playButtonVisible = !playButtonVisible;return false;}@Overridepublic void onClick(View view) {switch (view.getId()) {case R.id.movie_videoview_play:if (!playPause) {movie_play.setText("Pause");} else {movie_play.setText("Play");}playPause = !playPause;int nowTime = videoView.getCurrentPosition();Log.i(TAG, "nowTime: " + nowTime);try {screenShot(videoView, nowTime); //点击按钮截图,注意参数为videoView} catch (Exception e) {e.printStackTrace();}break;default:break;}}public void screenShot(View view, int nowTime) throws Exception {view.measure(MeasureSpec.makeMeasureSpec(0, MeasureSpec.UNSPECIFIED), MeasureSpec.makeMeasureSpec(0, MeasureSpec.UNSPECIFIED));view.layout(0, 0, view.getMeasuredWidth(), view.getMeasuredHeight());view.setDrawingCacheEnabled(true);view.buildDrawingCache();Bitmap bitmap = Bitmap.createBitmap(view.getDrawingCache());String path = Environment.getExternalStorageDirectory() + "/bitmap/" + nowTime + ".png";FileOutputStream fileOutputStream = null;try {fileOutputStream = new FileOutputStream(path);bitmap.compress(Bitmap.CompressFormat.PNG, 90, fileOutputStream);Log.i(TAG, "i: " + nowTime);} catch (Exception e) {Log.i(TAG, "Error: " + nowTime);e.printStackTrace();} finally {if (fileOutputStream != null) {fileOutputStream.close();}}bitmap.recycle();view.setDrawingCacheEnabled(false);} }
DrawingCache 获取其他控件如Button等View时正常。
六.VideoView播放视频,MediaMetadataRetriever获取帧画面(就是你了!)
能够正常获取帧画面,并且画面之间不重复,即不是只取关键帧,而是去取相应时间点的帧画面。若不保存为图片(.png/.jpg),耗时最多为0.4s,基本达到要求。
参考:http://yashirocc.blog.sohu.com/175636801.html
public class MoviePlayerActivity extends Activity implements OnTouchListener, OnClickListener, Runnable {private static final String TAG = "ImageLight";private String file_path;private VideoView videoView;private Button movie_play;private boolean playButtonVisible;private boolean playPause;@Overrideprotected void onCreate(Bundle savedInstanceState) {getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN, WindowManager.LayoutParams.FLAG_FULLSCREEN); // full screenrequestWindowFeature(Window.FEATURE_NO_TITLE); // no titlesetRequestedOrientation(ActivityInfo.SCREEN_ORIENTATION_LANDSCAPE); // landscape or horizontal screensuper.onCreate(savedInstanceState);setContentView(R.layout.movie_player_activity);movie_play = (Button) findViewById(R.id.movie_videoview_play);movie_play.setOnClickListener(this);movie_play.setText("Play");Intent intent = getIntent();file_path = intent.getStringExtra("file_path");videoView = (VideoView) findViewById(R.id.movie_palyer_videoview);videoView.setMediaController(null);// videoView.setMediaController(new MediaController(this)); videoView.setVideoPath(file_path);videoView.start();videoView.requestFocus();Thread screenShootThread = new Thread(this);screenShootThread.start();videoView.setOnTouchListener(this);}@Overridepublic void run() {MediaMetadataRetriever metadataRetriever = new MediaMetadataRetriever();metadataRetriever.setDataSource(file_path);for (int i = 40000 * 1000; i < 50 * 1000 * 1000; i += 500 * 1000) { // try { // Thread.sleep(500); // } catch (InterruptedException e) { // e.printStackTrace(); // } Bitmap bitmap = metadataRetriever.getFrameAtTime(videoView.getCurrentPosition()*1000, MediaMetadataRetriever.OPTION_CLOSEST);Log.i(TAG, "bitmap---i: " + i/1000);String path = Environment.getExternalStorageDirectory() + "/bitmap/" + i + ".png";FileOutputStream fileOutputStream = null;try {fileOutputStream = new FileOutputStream(path);bitmap.compress(Bitmap.CompressFormat.PNG, 90, fileOutputStream);Log.i(TAG, "i: " + i/1000);} catch (Exception e) {Log.i(TAG, "Error: " + i/1000);e.printStackTrace();} finally {if (fileOutputStream != null) {try {fileOutputStream.close();} catch (IOException e) {e.printStackTrace();}}} bitmap.recycle();}}@Overridepublic boolean onTouch(View v, MotionEvent event) {if (!playButtonVisible) {movie_play.setVisibility(View.VISIBLE);movie_play.setEnabled(true);} else {movie_play.setVisibility(View.INVISIBLE);}playButtonVisible = !playButtonVisible;return false;}@Overridepublic void onClick(View view) {switch (view.getId()) {case R.id.movie_videoview_play:if (!playPause) {movie_play.setText("Pause");} else {movie_play.setText("Play");}playPause = !playPause;break;default:break;}} }
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