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Android使用FFMpeg实现推送视频直播流到服务器
背景
在过去的2015年中,视频直播页的新宠无疑是户外直播。随着4G网络的普及和覆盖率的提升,主播可以在户外通过手机进行直播。而观众也愿意为这种可以足不出户而观天下事的服务买单。基于这样的背景,本文主要实现在Android设备上采集视频并推流到服务器。
概览
如下图所示,在安卓上采集并推流主要应用到两个类。首先是安卓Api自带的Camera,实现从摄像头采集图像。然后是Javacv 中的FFMpegFrameRecorder类实现对Camera采集到的帧编码并推流。
关键步骤与代码
下面结合上面的流程图给出视频采集的关键步骤。 首先是Camera类的初始化。
// 初始化Camera设备cameraDevice = Camera.open(); Log.i(LOG_TAG, "cameara open"); cameraView = new CameraView(this, cameraDevice);
上面的CameraView类是我们实现的负责预览视频采集和将采集到的帧写入FFMpegFrameRecorder的类。具体代码如下:
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(); //设置SurfaceView 的SurfaceHolder的回调函数 mHolder.addCallback(CameraView.this); mHolder.setType(SurfaceHolder.SURFACE_TYPE_PUSH_BUFFERS); //设置Camera预览的回调函数 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; } }); // Pick the first preview size that is equal or bigger, or pick the last (biggest) option if we cannot // reach the initial settings of imageWidth/imageHeight. for (int i = 0; i < sizes.size(); i++) { if ((sizes.get(i).width >= imageWidth && sizes.get(i).height >= imageHeight) || i == sizes.size() - 1) { imageWidth = sizes.get(i).width; imageHeight = sizes.get(i).height; Log.v(LOG_TAG, "Changed to supported resolution: " + imageWidth + "x" + imageHeight); break; } } 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); // 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; } //如果是录播,则把该帧先存在内存中 if (RECORD_LENGTH > 0) { int i = imagesIndex++ % images.length; yuvImage = images[i]; timestamps[i] = 1000 * (System.currentTimeMillis() - startTime); } if (yuvImage != null && recording) { ((ByteBuffer) yuvImage.image[0].position(0)).put(data); //如果是直播则直接写入到FFmpegFrameRecorder中 if (RECORD_LENGTH <= 0) try { Log.v(LOG_TAG, "Writing Frame"); long t = 1000 * (System.currentTimeMillis() - startTime); if (t > recorder.getTimestamp()) { recorder.setTimestamp(t); } recorder.record(yuvImage); } catch (FFmpegFrameRecorder.Exception e) { Log.v(LOG_TAG, e.getMessage()); e.printStackTrace(); } } }}
初始化FFmpegFrameRecorder类
recorder = new FFmpegFrameRecorder(ffmpeg_link, imageWidth, imageHeight, 1); //设置视频编码 28 指代h.264 recorder.setVideoCodec(28); recorder.setFormat("flv"); //设置采样频率 recorder.setSampleRate(sampleAudioRateInHz); // 设置帧率,即每秒的图像数 recorder.setFrameRate(frameRate); //音频采集线程 audioRecordRunnable = new AudioRecordRunnable(); audioThread = new Thread(audioRecordRunnable); runAudioThread = true;
其中的AudioRecordRunnable是我们自己实现的音频采集线程,代码如下
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); //如果是录播,则需要录播长度的缓存 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 { //直播只需要相当于一帧的音频的数据缓存 audioData = http://www.mamicode.com/ShortBuffer.allocate(bufferSize);"hljs-string">"audioRecord.startRecording()"); audioRecord.startRecording(); /* ffmpeg_audio encoding loop */ while (runAudioThread) { if (RECORD_LENGTH > 0) { audioData = http://www.mamicode.com/samples[samplesIndex++ % samples.length];"hljs-number">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) { //如果是直播,则直接调用recordSamples 将音频写入Recorder 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"); } }}
接下来是开始直播和停止直播的方法
//开始直播public void startRecording() { initRecorder(); try { recorder.start(); startTime = System.currentTimeMillis(); recording = true; audioThread.start(); } catch (FFmpegFrameRecorder.Exception e) { e.printStackTrace(); }}public void stopRecording() { //停止音频线程 runAudioThread = false; try { audioThread.join(); } catch (InterruptedException e) { e.printStackTrace(); } audioRecordRunnable = null; audioThread = null; if (recorder != null && recording) { //如果是录播,则将缓存中的帧加上时间戳后写入 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; } for (int i = firstIndex; i <= lastIndex; i++) { long t = timestamps[i % timestamps.length] - startTime; if (t >= 0) { if (t > recorder.getTimestamp()) { recorder.setTimestamp(t); } recorder.record(images[i % images.length]); } } 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++) { 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; }}
以上即为关键的步骤和代码,下面给出完整项目地址 RtmpRecorder
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Android使用FFMpeg实现推送视频直播流到服务器
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