Android MediaCodec录屏设置录制音频

要在Android中使用MediaCodec录制屏幕和音频，可以使用MediaProjection API和AudioRecord API。

首先，需要获取MediaProjection对象来捕获屏幕内容。可以使用MediaProjectionManager来请求用户授权并获取MediaProjection对象。例如：

MediaProjectionManager mediaProjectionManager = (MediaProjectionManager) getSystemService(Context.MEDIA_PROJECTION_SERVICE);
Intent intent = mediaProjectionManager.createScreenCaptureIntent();
startActivityForResult(intent, REQUEST_CODE_SCREEN_CAPTURE);

在onActivityResult回调方法中获取MediaProjection对象：

@Override
protected void onActivityResult(int requestCode, int resultCode, Intent data) {
    if (requestCode == REQUEST_CODE_SCREEN_CAPTURE && resultCode == RESULT_OK) {
        mMediaProjection = mediaProjectionManager.getMediaProjection(resultCode, data);
    }
}

接下来，需要创建一个AudioRecord对象来录制音频。可以使用MediaRecorder.AudioSource.MIC作为音频来源。例如：

int audioSource = MediaRecorder.AudioSource.MIC;
int sampleRate = 44100;
int channelCount = AudioFormat.CHANNEL_IN_MONO;
int audioFormat = AudioFormat.ENCODING_PCM_16BIT;
int bufferSize = AudioRecord.getMinBufferSize(sampleRate, channelCount, audioFormat);
mAudioRecord = new AudioRecord(audioSource, sampleRate, channelCount, audioFormat, bufferSize);

在录制音频时，需要以相同的速率将音频数据传递给编码器。可以使用线程循环读取音频数据并将其传递给编码器。例如：

mAudioRecord.startRecording();
while (!mStopRecording) {
    int numBytesRead = mAudioRecord.read(mAudioBuffer, 0, mAudioBuffer.length);
    if (numBytesRead > 0) {
        ByteBuffer inputBuffer = mAudioEncoder.getInputBuffer(inputBufferIndex);
        inputBuffer.clear();
        inputBuffer.put(mAudioBuffer, 0, numBytesRead);
        mAudioEncoder.queueInputBuffer(inputBufferIndex, 0, numBytesRead, presentationTimeUs, 0);
        presentationTimeUs += 1000000L / sampleRate;
    }
}
mAudioRecord.stop();

在编码视频和音频后，需要将它们合并为一个视频文件。可以使用MediaMuxer将它们合并在一起。例如：

mMediaMuxer = new MediaMuxer(outputFile.getAbsolutePath(), MediaMuxer.OutputFormat.MUXER_OUTPUT_MPEG_4);
int audioTrackIndex = -1;
while (true) {
    MediaCodec.BufferInfo bufferInfo = new MediaCodec.BufferInfo();
    int trackIndex = mAudioEncoder.dequeueOutputBuffer(bufferInfo, 0);
    if (trackIndex == MediaCodec.INFO_TRY_AGAIN_LATER) {
        break;
    } else if (trackIndex == MediaCodec.INFO_OUTPUT_FORMAT_CHANGED) {
        MediaFormat audioFormat = mAudioEncoder.getOutputFormat();
        audioTrackIndex = mMediaMuxer.addTrack(audioFormat);
        mMediaMuxer.start();
    } else if (trackIndex >= 0) {
        ByteBuffer outputBuffer = mAudioEncoder.getOutputBuffer(trackIndex);
        outputBuffer.position(bufferInfo.offset);
        outputBuffer.limit(bufferInfo.offset + bufferInfo.size);
        bufferInfo.presentationTimeUs = presentationTimeUs;
        mMediaMuxer.writeSampleData(audioTrackIndex, outputBuffer, bufferInfo);
        mAudioEncoder.releaseOutputBuffer(trackIndex, false);
    }
}

这样，你就可以使用MediaCodec同时录制屏幕和音频了。