Android MediaCodec 使用例子

下面的例子是使用MediaCodec 录制到文件的例子。

public class AvcEncoder { private MediaCodec mediaCodec; private BufferedOutputStream outputStream; public AvcEncoder() { File f = new File(Environment.getExternalStorageDirectory(), "Download/video_encoded.264"); touch (f); try { outputStream = new BufferedOutputStream(new FileOutputStream(f)); Log.i("AvcEncoder", "outputStream initialized"); } catch (Exception e){ e.printStackTrace(); } mediaCodec = MediaCodec.createEncoderByType("video/avc"); MediaFormat mediaFormat = MediaFormat.createVideoFormat("video/avc", 320, 240); mediaFormat.setInteger(MediaFormat.KEY_BIT_RATE, 125000); mediaFormat.setInteger(MediaFormat.KEY_FRAME_RATE, 15); mediaFormat.setInteger(MediaFormat.KEY_COLOR_FORMAT, MediaCodecInfo.CodecCapabilities.COLOR_FormatYUV420Planar); mediaFormat.setInteger(MediaFormat.KEY_I_FRAME_INTERVAL, 5); mediaCodec.configure(mediaFormat, null, null, MediaCodec.CONFIGURE_FLAG_ENCODE); mediaCodec.start(); } public void close() { try { mediaCodec.stop(); mediaCodec.release(); outputStream.flush(); outputStream.close(); } catch (Exception e){ e.printStackTrace(); } } // called from Camera.setPreviewCallbackWithBuffer(...) in other class public void offerEncoder(byte[] input) { try { ByteBuffer[] inputBuffers = mediaCodec.getInputBuffers(); ByteBuffer[] outputBuffers = mediaCodec.getOutputBuffers(); int inputBufferIndex = mediaCodec.dequeueInputBuffer(-1); if (inputBufferIndex >= 0) { ByteBuffer inputBuffer = inputBuffers[inputBufferIndex]; inputBuffer.clear(); inputBuffer.put(input); mediaCodec.queueInputBuffer(inputBufferIndex, 0, input.length, 0, 0); } MediaCodec.BufferInfo bufferInfo = new MediaCodec.BufferInfo(); int outputBufferIndex = mediaCodec.dequeueOutputBuffer(bufferInfo,0); while (outputBufferIndex >= 0) { ByteBuffer outputBuffer = outputBuffers[outputBufferIndex]; byte[] outData = new byte[bufferInfo.size]; outputBuffer.get(outData); outputStream.write(outData, 0, outData.length); Log.i("AvcEncoder", outData.length + " bytes written"); mediaCodec.releaseOutputBuffer(outputBufferIndex, false); outputBufferIndex = mediaCodec.dequeueOutputBuffer(bufferInfo, 0); } } catch (Throwable t) { t.printStackTrace(); } }

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。