实时音频可视化与生成音频样本同步问题求助

正在构建一款可视化生成音频样本波形的应用，该应用持续生成音频样本、填充缓冲区并将其提供给WASAPI进行播放。用户可通过按下不同键盘按键（覆盖C4到B4范围，对应频率261.6256 Hz至493.8833 Hz）更改生成音频的频率。目前音频生成功能运行正常，但实现实时波形可视化（显示扬声器当前播放的波形）时遇到瓶颈，已尝试多种方案均未解决：

• 尝试直接获取WASAPI待播放音频缓冲区指针，未找到可行方法；
• 使用最近提交的缓冲区数据近似波形，因音频生成循环与渲染循环的时序/同步问题，出现正弦波形重叠；
• 基于按键时长估算波形，存在抖动且重叠问题仍存在；
• 在渲染循环中添加std::cout或锁定帧率，要么程序卡顿要么重叠/闪烁问题并存；
• 关闭背景清除后，发现波形存在相位偏移；
• 后续更新为环形缓冲区+事件回调模式，又尝试将过零点固定在窗口左侧，问题仍未解决。

音频生成核心代码 #

void Update()
{
    static float prev_freq = 0;
    //process input & events
    {
        if (main_window->IsKeyPressed(KeyCode::C))
        {
            pressed = PIANO::C;
            frequency = C4_FREQUENCY;
        }
        else if (main_window->IsKeyPressed(KeyCode::F))
        {
            pressed = PIANO::C_SHARP;
            frequency = C4_SHARP_FREQUENCY;
        }

        else
        {
            pressed = PIANO::NONE;
            frequency = 0.0f;
        }
    }

    if (prev_freq != frequency)
    {
        prev_freq = frequency;
        time_held = 0;
    }

    
    //grab all available audio frames
    static float time = 0;
    HRESULT hr;
    UINT32 num_frames, padding_frames;

    hr = pAudioClient->GetBufferSize(&num_frames);
    hr = pAudioClient->GetCurrentPadding(&padding_frames);
    available_frames = num_frames - padding_frames;

    //write data to audio frames
    hr = pAudioRenderClient->GetBuffer(available_frames, (BYTE**)&buffer);
    for (unsigned int i = 0; i < available_frames; i++)
    {
        float amp = max_amplitude * sin(2 * PI * frequency * time);
        buffer[i] = (int16_t)amp;
        time += 1.f / wave_fmt->nSamplesPerSec;
    }
    hr = pAudioRenderClient->ReleaseBuffer(available_frames, NULL);
    
    //time one key has been held in milliseconds
    time_held += (frequency == 0 ? (-time_held) : dt);
}

内容的提问来源于stack exchange，提问作者J.T. Freeman