问Monodroid如何同步播放多个mp3

EN

var fd = this.Resources.OpenRawResourceFd(Resource.Raw.PianoInsideMics);

var extractor = new MediaExtractor();
extractor.SetDataSource(fd.FileDescriptor, fd.StartOffset, fd.Length);
extractor.SelectTrack(0);

var trackFormat = extractor.GetTrackFormat(0);

var decoder = MediaCodec.CreateDecoderByType(trackFormat.GetString(MediaFormat.KeyMime));
decoder.Configure(trackFormat, null, null, MediaCodecConfigFlags.None);

var thread = new Thread(() =>
{
    decoder.Start();
    var decoderInputBuffers = decoder.GetInputBuffers();
    var decoderOutputBuffers = decoder.GetOutputBuffers();

    var inputIndex = decoder.DequeueInputBuffer(-1);
    var inputBuffer = decoderInputBuffers[inputIndex];
    var bufferInfo = new MediaCodec.BufferInfo();
    byte[] audioBuffer = null;
    AudioTrack audioTrack = null;

    var read = extractor.ReadSampleData(inputBuffer, 0);
    while (read > 0)
    {
        decoder.QueueInputBuffer(inputIndex, 0, read, extractor.SampleTime,
            extractor.SampleFlags == MediaExtractorSampleFlags.Sync ? MediaCodecBufferFlags.SyncFrame : MediaCodecBufferFlags.None);

        extractor.Advance();

        var outputIndex = decoder.DequeueOutputBuffer(bufferInfo, -1);
        if (outputIndex == (int) MediaCodecInfoState.OutputFormatChanged)
        {
            trackFormat = decoder.OutputFormat;
        }
        else if (outputIndex >= 0)
        {
            if (bufferInfo.Size > 0)
            {
                var outputBuffer = decoderOutputBuffers[outputIndex];
                if (audioBuffer == null || audioBuffer.Length < bufferInfo.Size)
                {
                    audioBuffer = new byte[bufferInfo.Size];
                    Debug.WriteLine("Allocated new audiobuffer: {0}", audioBuffer.Length);
                }

                outputBuffer.Rewind();
                outputBuffer.Get(audioBuffer, 0, bufferInfo.Size);
                decoder.ReleaseOutputBuffer(outputIndex, false);

                if (audioTrack == null)
                {
                    var sampleRateInHz = trackFormat.GetInteger(MediaFormat.KeySampleRate);
                    var channelCount = trackFormat.GetInteger(MediaFormat.KeyChannelCount);
                    var channelConfig = channelCount == 1 ? ChannelOut.Mono : ChannelOut.Stereo;

                    audioTrack = new AudioTrack(
                        Stream.Music,
                        sampleRateInHz,
                        channelConfig,
                        Encoding.Pcm16bit,
                        AudioTrack.GetMinBufferSize(sampleRateInHz, channelConfig, Encoding.Pcm16bit)*2,
                        AudioTrackMode.Stream);

                    audioTrack.Play();
                }

                audioTrack.Write(audioBuffer, 0, bufferInfo.Size);
            }
        }

        inputIndex = decoder.DequeueInputBuffer(-1);
        inputBuffer = decoderInputBuffers[inputIndex];

        read = extractor.ReadSampleData(inputBuffer, 0);
    }
});