AudioRecord回调给多个MediaCodec编码的示例代码

以下是一个AudioRecord回调给多个MediaCodec编码的示例代码：

public class AudioEncoder {
    private static final String TAG = "AudioEncoder";
    private static final String MIME_TYPE = "audio/mp4a-latm";
    private static final int SAMPLE_RATE = 44100;
    private static final int CHANNEL_COUNT = 1;
    private static final int BIT_RATE = 64000;

    private AudioRecord mAudioRecord;
    private MediaCodec mMediaCodec;
    private boolean mIsRecording;
    private ByteBuffer[] mInputBuffers;
    private ByteBuffer[] mOutputBuffers;
    private MediaCodec.BufferInfo mBufferInfo;
    private List<MediaMuxerWrapper> mMuxerWrappers;

    public void startRecording() {
        mIsRecording = true;
        mAudioRecord.startRecording();

        try {
            mMediaCodec = MediaCodec.createEncoderByType(MIME_TYPE);
            MediaFormat format = MediaFormat.createAudioFormat(MIME_TYPE, SAMPLE_RATE, CHANNEL_COUNT);
            format.setInteger(MediaFormat.KEY_BIT_RATE, BIT_RATE);
            format.setInteger(MediaFormat.KEY_AAC_PROFILE, MediaCodecInfo.CodecProfileLevel.AACObjectLC);
            mMediaCodec.configure(format, null, null, MediaCodec.CONFIGURE_FLAG_ENCODE);
            mMediaCodec.start();

            mInputBuffers = mMediaCodec.getInputBuffers();
            mOutputBuffers = mMediaCodec.getOutputBuffers();
            mBufferInfo = new MediaCodec.BufferInfo();

            new Thread(new Runnable() {
                @Override
                public void run() {
                    while (mIsRecording) {
                        int index = mMediaCodec.dequeueInputBuffer(-1);
                        if (index >= 0) {
                            ByteBuffer inputBuffer = mInputBuffers[index];
                            inputBuffer.clear();
                            int bufferSize = mAudioRecord.read(inputBuffer, inputBuffer.capacity());
                            if (bufferSize >= 0) {
                                long presentationTimeUs = System.nanoTime() / 1000;
                                mMediaCodec.queueInputBuffer(index, 0, bufferSize, presentationTimeUs, 0);
                            }
                        }

                        int outputIndex = mMediaCodec.dequeueOutputBuffer(mBufferInfo, 0);
                        while (outputIndex >= 0) {
                            ByteBuffer outputBuffer = mOutputBuffers[outputIndex];
                            outputBuffer.position(mBufferInfo.offset);
                            outputBuffer.limit(mBufferInfo.offset + mBufferInfo.size);

                            for (MediaMuxerWrapper muxerWrapper : mMuxerWrappers) {
                                muxerWrapper.writeSampleData(AudioMuxerWrapper.TRACK_INDEX, outputBuffer, mBufferInfo);
                            }

                            mMediaCodec.releaseOutputBuffer(outputIndex, false);
                            outputIndex = mMediaCodec.dequeueOutputBuffer(mBufferInfo, 0);
                        }
                    }
                }
            }).start();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    public void stopRecording() {
        mIsRecording = false;
        mAudioRecord.stop();
        mMediaCodec.stop();
        mMediaCodec.release();
    }

    public void addMuxerWrapper(MediaMuxerWrapper muxerWrapper) {
        mMuxerWrappers.add(muxerWrapper);
    }
}

这个示例代码中，我们启动一个AudioRecord对象，然后启动一个MediaCodec对象，使用MediaCodec API将音频数据编码为AAC格式。我们将编码器的输出提供给一个MediaMuxerWrapper对象，它可以将音频数据写入一个MP4文件中。我们可以在不同的线程中同时启动多个MediaMuxerWrapper对象，这样我们就可以将音频数据写入多个MP4文件中。