Unity中AudioClip.PCMReaderCallback写入audioBuffer后未触发求助

1. BinaryReader关闭底层MemoryStream导致后续读取失效 #

你在PcmReader中用using包裹BinaryReader，默认情况下BinaryReader会关闭底层的MemoryStream，第一次回调执行后，audioBuffer就被关闭，后续无法再写入或读取数据，回调自然无法正常触发。

修复：
创建BinaryReader时指定不关闭底层流，手动释放BinaryReader而非底层流：

private void PcmReader(float[] data)
{
    // ... 其他逻辑 ...
    var reader = new BinaryReader(audioBuffer, Encoding.Default, leaveOpen: true);
    try
    {
        Debug.Log("audioBuffer is read");
        for (int i = 0; i < data.Length; i++)
        {
            if (audioBuffer.Position < audioBuffer.Length)
            {
                short sample = reader.ReadInt16();
                data[i] = sample / 32768f;
            }
            else
            {
                data[i] = 0f;
            }
        }
    }
    finally
    {
        reader.Dispose(); // 释放BinaryReader，但保留底层流
    }
    // ... 其他逻辑 ...
}

2. AudioClip.Create参数错误 #

AudioClip.Create的第二个参数是总样本数，你当前设置的44100意味着音频仅1秒时长（44100样本 ÷ 44100采样率），如果WebSocket返回数据的速度慢于音频播放速度，可能还没收到数据，音频就已播放完毕，回调停止触发。

修复：
设置足够大的总样本数适配流式音频场景：

audioClip = AudioClip.Create("ElevenLabsTTS", int.MaxValue, 1, 44100, true, PcmReader);

3. 线程安全问题：WebSocket回调跨线程操作MemoryStream #

WebSocket的OnMessage回调运行在非Unity主线程，直接写入MemoryStream会和主线程的PcmReader回调产生线程冲突，导致数据损坏或读取异常。

修复：
添加锁保护audioBuffer的读写操作：

private readonly object bufferLock = new object();

// PcmReader中读取时加锁
lock (bufferLock)
{
    if (audioBuffer == null || audioBuffer.Length == 0) return;
    // ... 读取buffer的逻辑 ...
}

// WebSocket回调中写入时加锁
websocket.OnMessage += (bytes) =>
{
    string message = Encoding.UTF8.GetString(bytes);
    var data = JsonUtility.FromJson<MessageData>(message);
    if (data.audio != null)
    {
        byte[] audioData = System.Convert.FromBase64String(data.audio);
        lock (bufferLock)
        {
            audioBuffer.Write(audioData);
        }
        Debug.Log("Added audio data");
    }
};

4. 优化MemoryStream重置逻辑 #

读取完所有数据后，不仅要清空长度，还要重置Position到0，避免后续写入位置错误：

lock (bufferLock)
{
    if (audioBuffer.Position >= audioBuffer.Length)
    {
        audioBuffer.SetLength(0);
        audioBuffer.Position = 0;
    }
}

完整修复后的关键代码片段 #

Start方法 #

private MemoryStream audioBuffer;
private AudioClip audioClip;
private AudioSource audioSource;
private readonly object bufferLock = new object();

async void Start()
{
    Debug.Log("Start");
    audioBuffer = new MemoryStream();
    audioClip = AudioClip.Create("ElevenLabsTTS", int.MaxValue, 1, 44100, true, PcmReader);

    await ConnectToWebSocket();
    audioSource = GetComponent<AudioSource>();
    audioSource.clip = audioClip;
    audioSource.Play();
    Debug.Log("Playing audio clip");
}

PcmReader回调 #

private void PcmReader(float[] data)
{
    lock (bufferLock)
    {
        if (audioBuffer == null || audioBuffer.Length == 0)
        {
            Array.Fill(data, 0f);
            return;
        }

        var reader = new BinaryReader(audioBuffer, Encoding.Default, leaveOpen: true);
        try
        {
            Debug.Log("audioBuffer is read");
            for (int i = 0; i < data.Length; i++)
            {
                if (audioBuffer.Position < audioBuffer.Length)
                {
                    short sample = reader.ReadInt16();
                    data[i] = sample / 32768f;
                }
                else
                {
                    data[i] = 0f;
                }
            }
        }
        finally
        {
            reader.Dispose();
        }

        if (audioBuffer.Position >= audioBuffer.Length)
        {
            audioBuffer.SetLength(0);
            audioBuffer.Position = 0;
        }
    }
}

内容的提问来源于stack exchange，提问作者user9319865