Android MediaCodec 录屏时同时录制音频功能实现

在 Android 中实现同时录制屏幕和音频可以使用 MediaProjection API 和 MediaRecorder API。以下是一些步骤：

1. 获取屏幕录制权限

使用 MediaProjectionManager 获取 MediaProjection 对象，该对象允许您捕获屏幕内容。您需要向用户请求屏幕录制权限，然后使用 onActivityResult 方法获取 MediaProjection。

private MediaProjectionManager mProjectionManager;
private static final int REQUEST_CODE = 100;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    mProjectionManager = (MediaProjectionManager) getSystemService(Context.MEDIA_PROJECTION_SERVICE);

    Intent intent = mProjectionManager.createScreenCaptureIntent();
    startActivityForResult(intent, REQUEST_CODE);
}

@Override
protected void onActivityResult(int requestCode, int resultCode, Intent data) {
    if (requestCode == REQUEST_CODE && resultCode == RESULT_OK) {
        MediaProjection mediaProjection = mProjectionManager.getMediaProjection(resultCode, data);
        // TODO: Use mediaProjection object to capture screen
    }
}

2. 创建一个 MediaRecorder 对象

使用 MediaRecorder API 创建一个 MediaRecorder 对象并设置音频和视频编码器、分辨率、帧率、比特率等参数。然后设置音频源为麦克风，并启动录制。

MediaRecorder recorder = new MediaRecorder();
recorder.setAudioSource(MediaRecorder.AudioSource.MIC);
recorder.setVideoSource(MediaRecorder.VideoSource.SURFACE);
recorder.setOutputFormat(MediaRecorder.OutputFormat.MPEG_4);
recorder.setVideoEncoder(MediaRecorder.VideoEncoder.H264);
recorder.setAudioEncoder(MediaRecorder.AudioEncoder.AAC);
recorder.setVideoSize(width, height);
recorder.setVideoFrameRate(frameRate);
recorder.setVideoEncodingBitRate(bitRate);
recorder.setOutputFile(outputFile);
recorder.prepare();
recorder.start();

3. 将音频数据添加到视频文件中

使用 MediaCodec API 实现音频编码器，将麦克风捕获的音频数据编码为 AAC 格式，并将其写入到视频文件中。

MediaCodec encoder = MediaCodec.createEncoderByType("audio/mp4a-latm");
MediaFormat format = MediaFormat.createAudioFormat("audio/mp4a-latm", sampleRate, channelCount);
format.setInteger(MediaFormat.KEY_BIT_RATE, bitRate);
format.setInteger(MediaFormat.KEY_MAX_INPUT_SIZE, bufferSize);
encoder.configure(format, null, null, MediaCodec.CONFIGURE_FLAG_ENCODE);
encoder.start();

while (!stopRecording) {
    int inputBufferIndex = encoder.dequeueInputBuffer(-1);
    if (inputBufferIndex >= 0) {
        ByteBuffer inputBuffer = encoder.getInputBuffer(inputBufferIndex);
        inputBuffer.clear();
        int size = audioRecorder.read(inputBuffer, bufferSize);
        if (size > 0) {
            long presentationTimeUs = System.nanoTime() / 1000;
            encoder.queueInputBuffer(inputBufferIndex, 0, size, presentationTimeUs, 0);
        }
    }

    int outputBufferIndex = encoder.dequeueOutputBuffer(info, 0);
    if (outputBufferIndex >= 0) {
        ByteBuffer outputBuffer = encoder.getOutputBuffer(outputBufferIndex);
        outputBuffer.position(info.offset);
        outputBuffer.limit(info.offset + info.size);
        if ((info.flags & MediaCodec.BUFFER_FLAG_CODEC_CONFIG) != 0) {
            info.size = 0;
        }
        if (info.size > 0) {
            outputBuffer.position(info.offset);
            outputBuffer.limit(info.offset + info.size);
            muxer.writeSampleData(audioTrackIndex, outputBuffer, info);
        }
        encoder.releaseOutputBuffer(outputBufferIndex, false);
    }
}

4. 合并音视频文件

使用 MediaMuxer API 将视频文件和音频文件合并为一个文件。

MediaMuxer muxer = new MediaMuxer(outputFile, MediaMuxer.OutputFormat.MUXER_OUTPUT_MPEG_4);
int videoTrackIndex = muxer.addTrack(videoFormat);
int audioTrackIndex = muxer.addTrack(audioFormat);
muxer.start();

// Write video data
ByteBuffer buffer = ByteBuffer.allocate(bufferSize);
while (!stopRecording) {
    int size = encoder.dequeueOutputBuffer(bufferInfo, 0);
    if (size >= 0) {
        ByteBuffer outputBuffer = encoder.getOutputBuffer(size);
        outputBuffer.position(bufferInfo.offset);
        outputBuffer.limit(bufferInfo.offset + bufferInfo.size);
        muxer.writeSampleData(videoTrackIndex, outputBuffer, bufferInfo);
        encoder.releaseOutputBuffer(size, false);
    }
}

// Write audio data
while (true) {
    int trackIndex = audioExtractor.getSampleTrackIndex();
    if (trackIndex < 0) {
        break;
    }
    buffer.clear();
    int sampleSize = audioExtractor.readSampleData(buffer, 0);
    bufferInfo.presentationTimeUs = audioExtractor.getSampleTime();
    bufferInfo.flags = audioExtractor.getSampleFlags();
    muxer.writeSampleData(audioTrackIndex, buffer, bufferInfo);
    audioExtractor.advance();
}

muxer.stop();
muxer.release();

这些步骤应该能帮助您实现同时录制屏幕和音频的功能。