MediaCodec
是Android(api>=16)
提供的一个多媒体硬解编码库,能实现音视频的编解码。
工作原理:其内部有2个队列,一个是输入队列,一个是输出队列。输入队列负责存储编
解码前的原始数据存储,并输送给MediaCodec
处理;输出队列负责存储编解码后
的新数据,可以直接处理或保存到文件中。
AAC
的头部信息介绍 :https://blog.csdn.net/jay100500/article/details/52955232
//mediacodec private MediaFormat encoderFormat = null; private MediaCodec encoder = null; private FileOutputStream outputStream = null; private MediaCodec.BufferInfo info = null; private int perpcmsize = 0; private byte[] outByteBuffer = null; private int aacsamplerate = 4; private double recordTime = 0; private int audioSamplerate = 0; private void initMediacodec(int samperate, File outfile) { try { aacsamplerate = getADTSsamplerate(samperate); //立体声 encoderFormat = MediaFormat.createAudioFormat(MediaFormat.MIMETYPE_AUDIO_AAC, samperate, 2); //96kbps fm音质 encoderFormat.setInteger(MediaFormat.KEY_BIT_RATE, 96000); encoderFormat.setInteger(MediaFormat.KEY_AAC_PROFILE, MediaCodecInfo.CodecProfileLevel.AACObjectLC); encoderFormat.setInteger(MediaFormat.KEY_MAX_INPUT_SIZE, 4096); encoder = MediaCodec.createEncoderByType(MediaFormat.MIMETYPE_AUDIO_AAC); info = new MediaCodec.BufferInfo(); if(encoder == null) { MyLog.d("craete encoder wrong"); return; } recordTime = 0; encoder.configure(encoderFormat, null, null, MediaCodec.CONFIGURE_FLAG_ENCODE); outputStream = new FileOutputStream(outfile); encoder.start(); } catch (IOException e) { e.printStackTrace(); } } private void encodecPcmToAAc(int size, byte[] buffer) { if(buffer != null && encoder != null) { //录音时间 size/ 采样率*声道数 * bits/8 recordTime += size * 1.0 / (audioSamplerate * 2 * (16 / 8)); MyLog.d("recordTime = " + recordTime); //回掉 if(wlOnRecordTimeListener != null) { wlOnRecordTimeListener.onRecordTime((int) recordTime); } int inputBufferindex = encoder.dequeueInputBuffer(0); if(inputBufferindex >= 0) { ByteBuffer byteBuffer = encoder.getInputBuffers()[inputBufferindex]; byteBuffer.clear(); byteBuffer.put(buffer); encoder.queueInputBuffer(inputBufferindex, 0, size, 0, 0); } int index = encoder.dequeueOutputBuffer(info, 0); while(index >= 0) { try { perpcmsize = info.size + 7; outByteBuffer = new byte[perpcmsize]; ByteBuffer byteBuffer = encoder.getOutputBuffers()[index]; byteBuffer.position(info.offset); byteBuffer.limit(info.offset + info.size); addADtsHeader(outByteBuffer, perpcmsize, aacsamplerate); byteBuffer.get(outByteBuffer, 7, info.size); byteBuffer.position(info.offset); outputStream.write(outByteBuffer, 0, perpcmsize); encoder.releaseOutputBuffer(index, false); index = encoder.dequeueOutputBuffer(info, 0); outByteBuffer = null; } catch (IOException e) { e.printStackTrace(); } } } } private void addADtsHeader(byte[] packet, int packetLen, int samplerate) { int profile = 2; // AAC LC int freqIdx = samplerate; // samplerate int chanCfg = 2; // CPE packet[0] = (byte) 0xFF; // 0xFFF(12bit) 这里只取了8位,所以还差4位放到下一个里面 packet[1] = (byte) 0xF9; // 第一个t位放F packet[2] = (byte) (((profile - 1) << 6) + (freqIdx << 2) + (chanCfg >> 2)); packet[3] = (byte) (((chanCfg & 3) << 6) + (packetLen >> 11)); packet[4] = (byte) ((packetLen & 0x7FF) >> 3); packet[5] = (byte) (((packetLen & 7) << 5) + 0x1F); packet[6] = (byte) 0xFC; } private int getADTSsamplerate(int samplerate) { int rate = 4; switch (samplerate) { case 96000: rate = 0; break; case 88200: rate = 1; break; case 64000: rate = 2; break; case 48000: rate = 3; break; case 44100: rate = 4; break; case 32000: rate = 5; break; case 24000: rate = 6; break; case 22050: rate = 7; break; case 16000: rate = 8; break; case 12000: rate = 9; break; case 11025: rate = 10; break; case 8000: rate = 11; break; case 7350: rate = 12; break; } return rate; } private void releaseMedicacodec() { if(encoder == null) { return; } try { recordTime = 0; outputStream.close(); outputStream = null; encoder.stop(); encoder.release(); encoder = null; encoderFormat = null; info = null; initmediacodec = false; MyLog.d("录制完成..."); } catch (IOException e) { e.printStackTrace(); } finally { if(outputStream != null) { try { outputStream.close(); } catch (IOException e) { e.printStackTrace(); } outputStream = null; } } }
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