从头开始创建 DSP 系统

发布于 2024-11-15 08:47:34 字数 896 浏览 3 评论 0原文

我喜欢电子音乐，并且对它的运作原理很感兴趣。我在 Stack Overflow 上发现了很多关于可用于播放音频、滤波器等的库的有用问题。但我真正好奇的是实际发生的情况：数据如何在效果器和振荡器之间传递？我已经对 dsp 的数学方面进行了研究，并且我已经解决了问题，但我不确定要使用什么缓冲系统等。最终目标是拥有一个传递数据的效果和振荡器的简单对象层次结构彼此之间（如果我最终没有拔出所有头发来尝试实现它，也许可以使用多线程）。它不会是下一个 Propellerhead Reason，但我对它是如何运作的很感兴趣，这更多的是一种练习，而不是产生最终产品的东西。

目前我使用 .net 和 C#，最近学习了 F#（这可能会也可能不会导致一些有趣的数据处理方式），但如果这些不适合这项工作，我可以在必要时学习另一个系统。

问题是：使用缓冲区通过程序获取大量信号数据的最佳方法是什么？例如，我使用队列、数组、链表等会更好吗？我应该使样本不可变并在每次向系统应用效果时创建一组新数据还是仅编辑缓冲区中的值？我是否应该有一个调度程序/线程池样式的对象来组织传递数据，或者效果函数应该直接在彼此之间传递数据？

谢谢。

编辑：另一个相关问题是我如何使用 Windows API 来播放这个数组？我真的不想使用 DirectShow，因为微软现在几乎已经让它消亡了

EDIT2：感谢所有的答案。在查看了所有技术之后，我将使用 XNA 4（我花了一些时间在互联网上搜索并发现这个网站解释了如何做到这一点）或 NAudio 来输出音乐......还不确定是哪一个，取决于系统最终的先进程度。当 C# 5.0 发布时，我将使用其异步功能在此基础上创建一个效果架构。我几乎平等地使用了每个人的答案，所以现在我遇到了一个难题，即该向谁提供赏金......

原文

I love electronic music and I am interested in how it all ticks.
I've found lots of helpful questions on Stack Overflow on libraries that can be used to play with audio, filters etc. But what I am really curious about is what is actually hapening: how is the data being passed between effects and oscillators? I have done research into the mathematical side of dsp and I've got that end of the problem sussed but I am unsure what buffering system to use etc. The final goal is to have a simple object heirarchy of effects and oscillators that pass the data between each other (maybe using multithreading if I don't end up pulling out all my hair trying to implement it). It's not going to be the next Propellerhead Reason but I am interested in how it all works and this is more of an exercise than something that will yeild an end product.

At the moment I use .net and C# and I have recently learnt F# (which may or may not lead to some interesting ways of handling the data) but if these are not suitable for the job I can learn another system if necessary.

The question is: what is the best way to get the large amounts of signal data through the program using buffers? For instance would I be better off using a Queue, Array,Linked List etc? Should I make the samples immutable and create a new set of data each time I apply an effect to the system or just edit the values in the buffer? Shoud I have a dispatcher/thread pool style object that organises passing data or should the effect functions pass data directly between each other?

Thanks.

EDIT: another related question is how would I then use the windows API to play this array? I don't really want to use DirectShow because Microsoft has pretty much left it to die now

EDIT2: thanks for all the answers. After looking at all the technologies I will either use XNA 4(I spent a while trawling the internet and found this site which explains how to do it) or NAudio to output the music... not sure which one yet, depends on how advanced the system ends up being. When C# 5.0 comes out I will use its async capabilities to create an effects architecture on top of that. I've pretty much used everybody's answer equally so now I have a conundrum of who to give the bounty to...

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疧_╮線 2024-11-22 08:47:34

您看过 VST.NET (http://vstnet.codeplex.com/) 吗？这是一个使用 C# 编写 VST 的库，它有一些示例。您还可以考虑编写 VST，以便可以从任何主机应用程序使用您的代码（但即使您不想，查看它们的代码也可能很有用）。

信号数据通常很大并且需要大量处理。不要使用链表！我知道的大多数库只是使用一个数组来放置所有音频数据（毕竟，这就是声卡所期望的）。

来自 VST.NET 示例：

    public override void Process(VstAudioBuffer[] inChannels, VstAudioBuffer[] outChannels)
    {
        VstAudioBuffer audioChannel = outChannels[0];

        for (int n = 0; n < audioChannel.SampleCount; n++)
        {
            audioChannel[n] = Delay.ProcessSample(inChannels[0][n]);
        }
    }

audioChannel 是非托管 float* 缓冲区的包装器。

您可能将样本存储在不可变数组中。然后，当您想要播放它们时，您可以复制输出缓冲区中的数据（如果需要，可以更改频率）并在此缓冲区中执行效果。请注意，您可以使用多个输出缓冲区（或通道）并在最后将它们相加。

编辑

我知道播放阵列的两种低级方法：Windows API 中的 DirectSound 和 WaveOut。使用 DirectSound 的 C# 示例。使用 WaveOut 的 C# 示例。但是，您可能更喜欢使用外部更高级别的库，例如 NAudio。 NAudio 对于 .NET 音频操作很方便 - 请参阅此博客文章，用于向声卡发送正弦波。您可以看到他们也使用浮点数组，这是我推荐的（如果您使用字节进行计算，最终会在声音中出现大量混叠）。

Have you looked at VST.NET (http://vstnet.codeplex.com/)? It's a library to write VST using C# and it has some examples. You can also consider writing a VST, so that your code can be used from any host application (but even if you don't want, looking at their code can be useful).

Signal data is usually big and requires a lot of processing. Do not use a linked list! Most libraries I know simply use an array to put all the audio data (after all, that's what the sound card expect).

From a VST.NET sample:

    public override void Process(VstAudioBuffer[] inChannels, VstAudioBuffer[] outChannels)
    {
        VstAudioBuffer audioChannel = outChannels[0];

        for (int n = 0; n < audioChannel.SampleCount; n++)
        {
            audioChannel[n] = Delay.ProcessSample(inChannels[0][n]);
        }
    }

The audioChannel is a wrapper around an unmanaged float* buffer.

You probably store your samples in an immutable array. Then, when you want to play them, you copy the data in the output buffer (change the frequency if you want) and perform effects in this buffer. Note you can use several output buffers (or channels) and sum them at the end.

Edit

I know two low-level ways to play your array: DirectSound and WaveOut from Windows API. C# Example using DirectSound. C# example with WaveOut. However, you might prefer use an external higher-level library, like NAudio. NAudio is convenient for .NET audio manipulation - see this blog post for sending a sine wave to the audio card. You can see they are also using an array of float, which is what I recommend (if you do your computations using bytes, you'll end up with a lot of aliasing in the sound).

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