一般方案：

1.通過mediaRecorder錄製視訊

2.通過isoviewer將分段的mp4合併

3.通過ffmpeg提取出mp4中的音訊

4.通過sox合併提取出的音訊和要新增的背景音樂

5.通過ffmpeg的命令列呼叫，實現音訊和視訊的合併

6.通過MediaMetadataRetriever獲取視訊在某一時刻的幀圖片

7.通過ffmpeg的命令列呼叫，實現新增水印

//音視訊合成

public static void muxVideoAudio(String videoFilePath, String audioFilePath, String outputFile) {
 try {
  MediaExtractor videoExtractor = new MediaExtractor();
  videoExtractor.setDataSource(videoFilePath);
  MediaExtractor audioExtractor = new MediaExtractor();
  audioExtractor.setDataSource(audioFilePath);
  MediaMuxer muxer = new MediaMuxer(outputFile, MediaMuxer.OutputFormat.MUXER_OUTPUT_MPEG_4);
  videoExtractor.selectTrack(0);
  MediaFormat videoFormat = videoExtractor.getTrackFormat(0);
  int videoTrack = muxer.addTrack(videoFormat);
  audioExtractor.selectTrack(0);
  MediaFormat audioFormat = audioExtractor.getTrackFormat(0);
  int audioTrack = muxer.addTrack(audioFormat);
  LogUtil.d(TAG, "Video Format " + videoFormat.toString());
  LogUtil.d(TAG, "Audio Format " + audioFormat.toString());
  boolean sawEOS = false;
  int frameCount = 0;
  int offset = 100;
  int sampleSize = 256 * 1024;
  ByteBuffer videoBuf = ByteBuffer.allocate(sampleSize);
  ByteBuffer audioBuf = ByteBuffer.allocate(sampleSize);
  MediaCodec.BufferInfo videoBufferInfo = new MediaCodec.BufferInfo();
  MediaCodec.BufferInfo audioBufferInfo = new MediaCodec.BufferInfo();
  videoExtractor.seekTo(0, MediaExtractor.SEEK_TO_CLOSEST_SYNC);
  audioExtractor.seekTo(0, MediaExtractor.SEEK_TO_CLOSEST_SYNC);
  muxer.start();
  while (!sawEOS) {
  videoBufferInfo.offset = offset;
  videoBufferInfo.size = videoExtractor.readSampleData(videoBuf, offset);
  if (videoBufferInfo.size < 0 || audioBufferInfo.size < 0) {
   sawEOS = true;
   videoBufferInfo.size = 0;
  } else {
   videoBufferInfo.presentationTimeUs = videoExtractor.getSampleTime();
   //noinspection WrongConstant
   videoBufferInfo.flags = videoExtractor.getSampleFlags();
   muxer.writeSampleData(videoTrack, videoBuf, videoBufferInfo);
   videoExtractor.advance();
   frameCount++;
  }
  }
   
  boolean sawEOS2 = false;
  int frameCount2 = 0;
  while (!sawEOS2) {
  frameCount2++;
  audioBufferInfo.offset = offset;
  audioBufferInfo.size = audioExtractor.readSampleData(audioBuf, offset);
  if (videoBufferInfo.size < 0 || audioBufferInfo.size < 0) {
   sawEOS2 = true;
   audioBufferInfo.size = 0;
  } else {
   audioBufferInfo.presentationTimeUs = audioExtractor.getSampleTime();
   //noinspection WrongConstant
   audioBufferInfo.flags = audioExtractor.getSampleFlags();
   muxer.writeSampleData(audioTrack, audioBuf, audioBufferInfo);
   audioExtractor.advance();
  }
  }
  muxer.stop();
  muxer.release();
  LogUtil.d(TAG,"Output: "+outputFile);
 } catch (IOException e) {
  LogUtil.d(TAG, "Mixer Error 1 " + e.getMessage());
 } catch (Exception e) {
  LogUtil.d(TAG, "Mixer Error 2 " + e.getMessage());
 }
 }
 

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