我正试图使用Android的AudioRecord和MediaCodec编码AAC音频。我创建了一个编码器类，与(使用Android MediaCodec从相机编码H.264)非常相似。使用此类，我创建了一个AudioRecord实例并告诉它将其byte []数据读取到AudioEncoder(audioEncoder.offerEncoder(Data))。
while(isRecording)
{
audioRecord.read(Data, 0, Data.length);
audioEncoder.offerEncoder(Data);
}
这是我AudioRecord的设置：
int audioSource = MediaRecorder.AudioSource.MIC;
int sampleRateInHz = 44100;
int channelConfig = AudioFormat.CHANNEL_IN_MONO;
int audioFormat = AudioFormat.ENCODING_PCM_16BIT;
int bufferSizeInBytes = AudioRecord.getMinBufferSize(sampleRateInHz, channelConfig, audioFormat);
我已经成功收集了一些byte[]数组数据并将其写入本地文件。不幸的是，该文件无法播放。我在网上进行了更多搜索，并找到了一篇相关的帖子（如何使用Android MediaCodec生成AAC ADTS基本流）。所以，其他遇到类似问题的人都表示主要问题是“MediaCodec编码器生成原始AAC流。原始AAC流需要转换为可播放的格式，例如ADTS流”。因此，我尝试添加ADTS头部。然而，在我添加ADTS头部之后（我在下面的代码中进行了注释），我的AudioEncoder甚至不会写入输出音频文件。我是否漏掉了什么？我的设置是正确的吗？
欢迎任何建议、评论和意见，非常感谢！谢谢大家！
import android.media.MediaCodec;
import android.media.MediaCodecInfo;
import android.media.MediaFormat;
import android.os.Environment;
import android.util.Log;
import java.io.BufferedOutputStream;
import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.nio.ByteBuffer;
public class AudioEncoder {
private MediaCodec mediaCodec;
private BufferedOutputStream outputStream;
private String mediaType = "audio/mp4a-latm";
public AudioEncoder() {
File f = new File(Environment.getExternalStorageDirectory(), "Download/audio_encoded.aac");
touch(f);
try {
outputStream = new BufferedOutputStream(new FileOutputStream(f));
Log.e("AudioEncoder", "outputStream initialized");
} catch (Exception e){
e.printStackTrace();
}
mediaCodec = MediaCodec.createEncoderByType(mediaType);
final int kSampleRates[] = { 8000, 11025, 22050, 44100, 48000 };
final int kBitRates[] = { 64000, 128000 };
MediaFormat mediaFormat = MediaFormat.createAudioFormat(mediaType,kSampleRates[3],1);
mediaFormat.setInteger(MediaFormat.KEY_AAC_PROFILE, MediaCodecInfo.CodecProfileLevel.AACObjectLC);
mediaFormat.setInteger(MediaFormat.KEY_BIT_RATE, kBitRates[1]);
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 AudioRecord's read
public synchronized void offerEncoder(byte[] input) {
Log.e("AudioEncoder", input.length + " is coming");
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);
////trying to add a ADTS
// while (outputBufferIndex >= 0) {
// int outBitsSize = bufferInfo.size;
// int outPacketSize = outBitsSize + 7; // 7 is ADTS size
// ByteBuffer outputBuffer = outputBuffers[outputBufferIndex];
//
// outputBuffer.position(bufferInfo.offset);
// outputBuffer.limit(bufferInfo.offset + outBitsSize);
//
// byte[] outData = new byte[outPacketSize];
// addADTStoPacket(outData, outPacketSize);
//
// outputBuffer.get(outData, 7, outBitsSize);
// outputBuffer.position(bufferInfo.offset);
//
//// byte[] outData = new byte[bufferInfo.size];
// outputStream.write(outData, 0, outData.length);
// Log.e("AudioEncoder", outData.length + " bytes written");
//
// mediaCodec.releaseOutputBuffer(outputBufferIndex, false);
// outputBufferIndex = mediaCodec.dequeueOutputBuffer(bufferInfo, 0);
//
// }
//Without ADTS header
while (outputBufferIndex >= 0) {
ByteBuffer outputBuffer = outputBuffers[outputBufferIndex];
byte[] outData = new byte[bufferInfo.size];
outputBuffer.get(outData);
outputStream.write(outData, 0, outData.length);
Log.e("AudioEncoder", outData.length + " bytes written");
mediaCodec.releaseOutputBuffer(outputBufferIndex, false);
outputBufferIndex = mediaCodec.dequeueOutputBuffer(bufferInfo, 0);
}
} catch (Throwable t) {
t.printStackTrace();
}
}
/**
* Add ADTS header at the beginning of each and every AAC packet.
* This is needed as MediaCodec encoder generates a packet of raw
* AAC data.
*
* Note the packetLen must count in the ADTS header itself.
**/
private void addADTStoPacket(byte[] packet, int packetLen) {
int profile = 2; //AAC LC
//39=MediaCodecInfo.CodecProfileLevel.AACObjectELD;
int freqIdx = 4; //44.1KHz
int chanCfg = 2; //CPE
// fill in ADTS data
packet[0] = (byte)0xFF;
packet[1] = (byte)0xF9;
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;
}
public void touch(File f)
{
try {
if(!f.exists())
f.createNewFile();
} catch (IOException e) {
e.printStackTrace();
}
}
}