Android MediaCodec 使用例子

下面的例子是使用MediaCodec 录制到文件的例子。

 1 public class AvcEncoder {  
 2   
 3 private MediaCodec mediaCodec;  
 4 private BufferedOutputStream outputStream;  
 5   
 6 public AvcEncoder() {   
 7     File f = new File(Environment.getExternalStorageDirectory(), "Download/video_encoded.264");  
 8     touch (f);  
 9     try {  
10         outputStream = new BufferedOutputStream(new FileOutputStream(f));  
11         Log.i("AvcEncoder", "outputStream initialized");  
12     } catch (Exception e){   
13         e.printStackTrace();  
14     }  
15   
16     mediaCodec = MediaCodec.createEncoderByType("video/avc");  
17     MediaFormat mediaFormat = MediaFormat.createVideoFormat("video/avc", 320, 240);  
18     mediaFormat.setInteger(MediaFormat.KEY_BIT_RATE, 125000);  
19     mediaFormat.setInteger(MediaFormat.KEY_FRAME_RATE, 15);  
20     mediaFormat.setInteger(MediaFormat.KEY_COLOR_FORMAT, MediaCodecInfo.CodecCapabilities.COLOR_FormatYUV420Planar);  
21     mediaFormat.setInteger(MediaFormat.KEY_I_FRAME_INTERVAL, 5);  
22     mediaCodec.configure(mediaFormat, null, null, MediaCodec.CONFIGURE_FLAG_ENCODE);  
23     mediaCodec.start();  
24 }  
25   
26 public void close() {  
27     try {  
28         mediaCodec.stop();  
29         mediaCodec.release();  
30         outputStream.flush();  
31         outputStream.close();  
32     } catch (Exception e){   
33         e.printStackTrace();  
34     }  
35 }  
36   
37 // called from Camera.setPreviewCallbackWithBuffer(...) in other class  
38 public void offerEncoder(byte[] input) {  
39     try {  
40         ByteBuffer[] inputBuffers = mediaCodec.getInputBuffers();  
41         ByteBuffer[] outputBuffers = mediaCodec.getOutputBuffers();  
42         int inputBufferIndex = mediaCodec.dequeueInputBuffer(-1);  
43         if (inputBufferIndex >= 0) {  
44             ByteBuffer inputBuffer = inputBuffers[inputBufferIndex];  
45             inputBuffer.clear();  
46             inputBuffer.put(input);  
47             mediaCodec.queueInputBuffer(inputBufferIndex, 0, input.length, 0, 0);  
48         }  
49   
50         MediaCodec.BufferInfo bufferInfo = new MediaCodec.BufferInfo();  
51         int outputBufferIndex = mediaCodec.dequeueOutputBuffer(bufferInfo,0);  
52         while (outputBufferIndex >= 0) {  
53             ByteBuffer outputBuffer = outputBuffers[outputBufferIndex];  
54             byte[] outData = new byte[bufferInfo.size];  
55             outputBuffer.get(outData);  
56             outputStream.write(outData, 0, outData.length);  
57             Log.i("AvcEncoder", outData.length + " bytes written");  
58   
59             mediaCodec.releaseOutputBuffer(outputBufferIndex, false);  
60             outputBufferIndex = mediaCodec.dequeueOutputBuffer(bufferInfo, 0);  
61   
62         }  
63     } catch (Throwable t) {  
64         t.printStackTrace();  
65     }  
66   
67 }
这个例子配置了编码格式、视频大小、比特率、帧率等参数，然后在camera 预览的回调函数里把yuv420数据推送给mediacodec，编码后取出nalu，写入到文件。