如何使用android MediaMuxer混合不同长度的音频和视频

Question

我想使用 android mediamuxer 混合视频（1 分钟）和音频（10 秒）。我希望音频重复直到视频结束。当我使用下面的代码时，音频只播放 10 秒。有谁知道如何解决这个问题？

 mediaMuxer.start();
        while ((sampleSize = videoExtra.readSampleData(videoBuffer, 0 )) != -1) {
            videoBufferInfo.offset = 0;
            videoBufferInfo.size = sampleSize;
            videoBufferInfo.presentationTimeUs = videoExtra.getSampleTime();
            videoBufferInfo.flags = videoExtra.getSampleFlags();
            mediaMuxer.writeSampleData(videoIndex, videoBuffer, videoBufferInfo);

            videoExtra.advance();
        }



        while ((audioSize = musicExtra.readSampleData(audioBuffer, 0)) != -1) {
            audioBufferInfo.offset = 0;
            audioBufferInfo.size = audioSize;
            audioBufferInfo.presentationTimeUs = musicExtra.getSampleTime();
            audioBufferInfo.flags = musicExtra.getSampleFlags();
            mediaMuxer.writeSampleData(audioIndex, audioBuffer, audioBufferInfo);
            musicExtra.advance();
        }
        musicExtra.seekTo(0, MediaExtractor.SEEK_TO_CLOSEST_SYNC);

        videoExtra.release();
        musicExtra.release();
        mediaMuxer.stop();
        mediaMuxer.release();

Answer 1

1. 三个输入参数：

   字符串视频路径、字符串音频路径、字符串输出路径

2. 获取视频时长及其曲目索引：

       videoExtractor = new MediaExtractor();
       videoExtractor.setDataSource(videoPath);
       MediaFormat videoFormat = null;
   
       int videoTrackCount = videoExtractor.getTrackCount();
       //vedio max input size
       int frameMaxInputSize = 0;
       int frameRate = 0;
       long videoDuration = 0;
   
       for (int i = 0; i < videoTrackCount; i++) {
           videoFormat = videoExtractor.getTrackFormat(i);
           String mimeType = videoFormat.getString(MediaFormat.KEY_MIME);
           if (mimeType.startsWith("video/")) {
               /*
                * just use the first track
                */
               videoTrackIndex = i;
               frameMaxInputSize = videoFormat.getInteger(MediaFormat.KEY_MAX_INPUT_SIZE);
               frameRate = videoFormat.getInteger(MediaFormat.KEY_FRAME_RATE);
               videoDuration = videoFormat.getLong(MediaFormat.KEY_DURATION);
               break;
           }
       }
   
       if (videoTrackIndex  < 0 ) {
           Log.e(TAG, "Error input file:: No Vedio track");
           return;
       }
   

3. 获取音频信息

       audioExtractor = new MediaExtractor();
       audioExtractor.setDataSource(audioPath);
       MediaFormat audioFormat = null;
   
       int audioTrackCount = audioExtractor.getTrackCount();
       audioExtractor = new MediaExtractor();
       int audioTrackCount = audioExtractor.getTrackCount();
       for (int i = 0; i < audioTrackCount; i++) {
           audioFormat = audioExtractor.getTrackFormat(i);
           String mimeType = audioFormat.getString(MediaFormat.KEY_MIME);
           if (mimeType.startsWith("audio/")) {
               audioTrackIndex = i;
               break;
           }
       }
   
       if (audioTrackIndex  < 0 ) {
           Log.e(TAG, "Error input file:: No Audio track");
           return;
       }
   

4. 写入视频数据：

       MediaCodec.BufferInfo videoBufferInfo = new MediaCodec.BufferInfo();
       mediaMuxer = new MediaMuxer(outputPath, MediaMuxer.OutputFormat.MUXER_OUTPUT_MPEG_4);
       int writeVideoTrackIndex = mediaMuxer.addTrack(videoFormat);
       int writeAudioTrackIndex = mediaMuxer.addTrack(audioFormat);
       mediaMuxer.start();
   
       ByteBuffer byteBuffer = ByteBuffer.allocate(frameMaxInputSize);
       videoExtractor.unselectTrack(videoTrackIndex);
       videoExtractor.selectTrack(videoTrackIndex);
   
       while (true) {
           int readVideoSampleSize = videoExtractor.readSampleData(byteBuffer, 0);
           if (readVideoSampleSize < 0) {
               videoExtractor.unselectTrack(videoTrackIndex);
               break;
           }
           long videoSampleTime = videoExtractor.getSampleTime();
           videoBufferInfo.size = readVideoSampleSize;
           videoBufferInfo.presentationTimeUs = videoSampleTime;
           //videoBufferInfo.presentationTimeUs += 1000 * 1000 / frameRate;
           videoBufferInfo.offset = 0;
           videoBufferInfo.flags = videoExtractor.getSampleFlags();
           mediaMuxer.writeSampleData(writeVideoTrackIndex, byteBuffer, videoBufferInfo);
           videoExtractor.advance();
       }
   

5. 写入音频数据

       long audioPresentationTimeUs = 0;
       MediaCodec.BufferInfo audioBufferInfo = new MediaCodec.BufferInfo();
       audioExtractor.selectTrack(audioTrackIndex);
       /*
        * the last audio presentation time.
        */
       long lastEndAudioTimeUs = 0;
       while (true) {
           int readAudioSampleSize = audioExtractor.readSampleData(byteBuffer, 0);
           if (readAudioSampleSize < 0) {
               //if end of the stream, unselect
               audioExtractor.unselectTrack(audioTrackIndex);
               if (audioPresentationTimeUs >= videoDuration) {
                   //if has reach the end of the video time ,just exit
                   break;
               } else {
                   //if not the end of the video time, just repeat.
                   lastEndAudioTimeUs += audioPresentationTimeUs;
                   audioExtractor.selectTrack(audioTrackIndex);
                   continue;
               }
           }
   
           long audioSampleTime = audioExtractor.getSampleTime();
           audioBufferInfo.size = readAudioSampleSize;
           audioBufferInfo.presentationTimeUs = audioSampleTime + lastEndAudioTimeUs;
           if (audioBufferInfo.presentationTimeUs > videoDuration) {
               audioExtractor.unselectTrack(audioTrackIndex);
               break;
           }
           audioPresentationTimeUs = audioBufferInfo.presentationTimeUs;
           audioBufferInfo.offset = 0;
           audioBufferInfo.flags = audioExtractor.getSampleFlags();
           mediaMuxer.writeSampleData(writeAudioTrackIndex, byteBuffer, audioBufferInfo);
           audioExtractor.advance();
       }
   

6. 释放资源。

      if (mediaMuxer != null) {
           try {
               mediaMuxer.stop();
               mediaMuxer.release();
           } catch (Exception e) {
               e.printStackTrace();
           }
       }
   
       if (videoExtractor != null) {
           try {
               videoExtractor.release();
           } catch (Exception e) {
               e.printStackTrace();
           }
       }
   
       if (audioExtractor != null) {
           try {
               audioExtractor.release();
           } catch (Exception e) {
               e.printStackTrace();
           }
       }
   

希望这会有所帮助！