如何录制Unity 场景中的声音

发布时间: 2022年05月10日阅读数: 2

有些时候我们在游戏想录制游戏内部的声音，那么常用的Unity的MicroPhone API就没什么用了。

好在Unity还提供了OnAudioFilterRead这个API来完成这类需求。

这个方案来自：http://evanxmerz.com/blog/index.php/2016/10/07/recording-in-game-audio-in-unity/

实现步骤：

创建MonoBehaviour，这个脚本需要附到Unity AudioListener 所在的GameObject才能正常工作

在脚本内添加代码

// write the incoming audio to the output string
void OnAudioFilterRead(float[] data, int channels)
{
    if (this.Rendering)
    {
        // store the number of channels we are rendering
        this.channels = channels;

        // store the data stream
        this.Write(data);
    }
}

将接收到的数据保存到字节流中

/// Write a chunk of data to the output stream.
public void Write(float[] audioData)
{
    // Convert numeric audio data to bytes
    for (int i = 0; i < audioData.Length; i++)
    {
        // write the short to the stream
        this.outputWriter.Write((short) (audioData[i] * (float) Int16.MaxValue));
    }
}

保存成声音文件

public AudioRenderer.Result Save(string filename)
{
  Result result = new AudioRenderer.Result();

  if (outputStream.Length > 0)
  {
      // add a header to the file so we can send it to the SoundPlayer
      this.AddHeader();

      // if a filename was passed in
      if (filename.Length > 0)
      {
          // Save to a file. Print a warning if overwriting a file.
          if (File.Exists(filename))
              Debug.LogWarning("Overwriting " + filename + "...");

          // reset the stream pointer to the beginning of the stream
          outputStream.Position = 0;

          // write the stream to a file
          FileStream fs = File.OpenWrite(filename);

          this.outputStream.WriteTo(fs);

          fs.Close();

          // for debugging only
          Debug.Log("Finished saving to " + filename + ".");
      }

      result.State = Status.SUCCESS;
  }
  else
  {
      Debug.LogWarning("There is no audio data to save!");

      result.State = Status.FAIL;
      result.Message = "There is no audio data to save!";
  }

  return result;
}

其中的AddHeader如下：

/// This generates a simple header for a canonical wave file,
/// which is the simplest practical audio file format. It
/// writes the header and the audio file to a new stream, then
/// moves the reference to that stream.
///
/// See this page for details on canonical wave files:
/// http://www.lightlink.com/tjweber/StripWav/Canon.html
private void AddHeader()
{
// reset the output stream
outputStream.Position = 0;


// calculate the number of samples in the data chunk
  long numberOfSamples = outputStream.Length / (BITS_PER_SAMPLE / 8);

  // create a new MemoryStream that will have both the audio data AND the header
  MemoryStream newOutputStream = new MemoryStream();
  BinaryWriter writer = new BinaryWriter(newOutputStream);

  writer.Write(0x46464952); // "RIFF" in ASCII

  // write the number of bytes in the entire file
  writer.Write((int) (HEADER_SIZE + (numberOfSamples * BITS_PER_SAMPLE * channels / 8)) - 8);

  writer.Write(0x45564157); // "WAVE" in ASCII
  writer.Write(0x20746d66); // "fmt " in ASCII
  writer.Write(16);

  // write the format tag. 1 = PCM
  writer.Write((short) 1);

  // write the number of channels.
  writer.Write((short) channels);

  // write the sample rate. 44100 in this case. The number of audio samples per second
  writer.Write(SAMPLE_RATE);

  writer.Write(SAMPLE_RATE * channels * (BITS_PER_SAMPLE / 8));
  writer.Write((short) (channels * (BITS_PER_SAMPLE / 8)));

  // 16 bits per sample
  writer.Write(BITS_PER_SAMPLE);

  // "data" in ASCII. Start the data chunk.
  writer.Write(0x61746164);

  // write the number of bytes in the data portion
  writer.Write((int) (numberOfSamples * BITS_PER_SAMPLE * channels / 8));

  // copy over the actual audio data
  this.outputStream.WriteTo(newOutputStream);

  // move the reference to the new stream
  this.outputStream = newOutputStream;
}

使用OnGUI代码测试

#if UNITY_EDITOR
void OnGUI()
{
    if (GUI.Button(new Rect(0, 0, 100, 100), "Start"))
    {
        this.Rendering = true;
    }

    if (GUI.Button(new Rect(0, 110, 100, 100), "Stop"))
    {
        this.Rendering = false;
        Save(Application.dataPath + "/" + "234.wav");
    }
}
#endif

如何录制Unity 场景中的声音

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