And in this tutorial we're going to talk to you about the Juice audio processor class.

在本教程中，我們將介紹 Juice 音頻處理器類。

The audio processor class is the way that you can write your plug-in code once but be able to turn your plug-in code into all the different formats that you're able to deploy for plugins such as VST3, AU, and AEX, and also be able to do those plug-ins on separate operating systems such as Windows and Mac OS.

通過音頻處理器類，您只需編寫一次插件代碼，就能將插件代碼轉換成 VST3、AU 和 AEX 等不同格式的插件，並能在 Windows 和 Mac OS 等不同作業系統上運行這些插件。

So we have two objectives for this tutorial.

是以，本教程有兩個目標。

The first objective is that we're going to dissect the Juice audio processor class.

第一個目標是，我們將剖析 Juice 音頻處理器類。

I've been doing Juice tutorials since 2017 and I'm embarrassed to say that I never really took the time until recently to dig into the audio processor class and really truly look at what it does and what each function is doing.

我從 2017 年起就開始做 Juice 教程，說來慚愧，直到最近我才真正花時間深入研究音頻處理器類，真真切切地瞭解它的作用和每個功能的作用。

So I'm going to do that with you today and show you some of the insights that I've gained along the way.

所以，我今天要和大家一起做這件事，並向大家展示我一路走來的一些感悟。

The second objective is that I'm going to show you the Juice audio processor class alongside the CMake file that we did in the last tutorial and show you how those two things relate to each other and how the configuration of your CMake file relates to the code that is actually generated for the Juice audio processor class.

第二個目標是，我將向你展示 Juice 音頻處理器類和 CMake 文件，並向你展示這兩個文件之間的關係，以及 CMake 文件的配置與 Juice 音頻處理器類實際生成的代碼之間的關係。

When one of my mentors showed me how these two files relate, it really helped me expand my mind map on how build systems and generated code actually relate to each other and helped me level up my skill set in a major way and I hope it levels up your skill set as well.

當我的一位導師向我展示這兩個文件之間的關係時，它真的幫我擴展了我的思維導圖，讓我瞭解構建系統和生成代碼之間的關係，並幫助我在很大程度上提升了我的技能，我希望它也能提升你的技能。

If you're ready to take that next step into audio plug-in development, I invite you to check out our latest book, The Complete Beginner's Guide to Audio Plug-in Development.

如果你已經準備好邁出音頻插件開發的下一步，我邀請你閱讀我們的最新著作《音頻插件開發完全入門指南》。

This has everything that you need to know to build your first audio plug-in, over 450 pages, and you can get it both on physical copy via Amazon and via ebook on our website theaudioprogrammer.com.

這本書有製作第一個音頻插件所需的一切知識，共 450 多頁，你可以通過亞馬遜購買實體版，也可以通過我們的網站 theaudioprogrammer.com 購買電子書。

This video is also brought to you today by our sponsor, JetBrains.

本視頻也由我們的贊助商 JetBrains 提供。

So I've been using their Sealion IDE for quite a while now and along with their great cross-platform experience of being able to switch back and forth between Windows and Mac and being able to find everything easily because the experience is largely the same.

我使用他們的 Sealion IDE 已經有一段時間了，他們的跨平臺體驗非常好，可以在 Windows 和 Mac 之間來回切換，而且因為體驗基本相同，所以很容易找到所有東西。

I've also been enjoying their integrated CMake support.

我也很喜歡他們集成的 CMake 支持。

It's been a lifesaver for me because I'm not an expert on build systems and being able to just double click on the CMake file and have it open up my project is a lifesaver.

這對我來說是個救星，因為我不是構建系統方面的專家，能夠雙擊 CMake 文件並打開我的項目是我的救星。

It also has the ability to be able to debug CMake files, which is really awesome.

它還能調試 CMake 文件，這真是太棒了。

I really love that feature.

我真的很喜歡這個功能。

Be sure to check out JetBrains and Sealion on the link below.

請務必通過下面的鏈接查看 JetBrains 和 Sealion。

And without further delay, let's get started.

事不宜遲，讓我們開始吧。

Okay, so here we are in our project and one thing that you'll notice is that I'm in my CMake file rather than having the ProJuicer.

好了，現在我們來到了項目中，你會注意到的一點是，我在 CMake 文件中，而不是在 ProJuicer 中。

And with that, I'm going to make a very small announcement, which is that moving forward, we're going to be doing our tutorials using CMake rather than the ProJuicer.

接下來，我要宣佈一個小消息，那就是今後我們將使用 CMake 而不是 ProJuicer 來編寫教程。

Now, I think that the ProJuicer is great if you know barely anything about C++ and about Guice and you're just starting to get off the ground and write some code and write your first plugin.

現在，如果你對 C++ 和 Guice 幾乎一無所知，而且剛剛開始編寫一些代碼和第一個插件，我認為 ProJuicer 是個不錯的選擇。

But I think once you start really getting serious about C++ development that you're probably going to want to start switching towards using a build system like CMake.

但我認為，一旦你開始真正認真地進行 C++ 開發，你可能就會開始轉向使用 CMake 這樣的構建系統。

This is a challenging step and it's been challenging for me.

這是具有挑戰性的一步，對我來說也是如此。

However, one thing that I will say is having been around a couple major music tech companies that all of them use something like CMake or another build system for generating their projects.

不過，有一點我要說的是，在幾家大型音樂技術公司工作過的人都會使用 CMake 或其他構建系統來生成項目。

None of them use the ProJuicer.

他們都沒有使用 ProJuicer。

Okay, so if you want to get into this and start doing this for a living, I would highly advise or recommend that you start learning build systems and learning at least the basics about them.

好了，如果你想進入這個行業並以此為生，我會強烈建議你開始學習構建系統，並至少學習有關它們的基礎知識。

And that's what I'm trying to do as well.

這也是我想做的。

So that's why we're working with CMake right now.

這就是我們現在使用 CMake 的原因。

So I know that this transition from the ProJuicer to CMake will feel a little bit intimidating for some.

所以我知道，從 ProJuicer 到 CMake 的過渡對某些人來說會有點嚇人。

But don't worry, we're going to take it slow and I'm going to try to show you every step of the way how everything is happening.

不過別擔心，我們會慢慢來，我會盡力向你們展示每一步是如何進行的。

So first thing I would say is watch the last tutorial because that's how we actually created the CMake file that we're seeing here right now.

所以我想說的第一件事就是觀看上一個教程，因為我們就是這樣創建了現在看到的 CMake 文件。

So the second thing I'm going to show you is something that I learned when I first started working with CMake that really helped me switch on the light in terms of what build systems do and what their intention is.

第二件事是我剛開始使用 CMake 時學到的，它讓我明白了構建系統的作用和意圖。

So if we scroll down here a little bit, what I'm going to show you is that in this juice add plugin function that we have a couple configuration options.

是以，如果我們向下滾動一點，我將向你展示的是，在這個果汁添加插件功能中，我們有幾個配置選項。

Okay, so the reason for this is let's just take the code and put it aside for a second.

好吧，之所以這樣做，是因為我們先把代碼放在一邊。

And let's just say that we were just having a conversation about creating a plugin.

這麼說吧，我們當時正在討論創建一個插件。

So one of the first questions that we would probably ask is, well, what kind of plugin do we want it to be?

是以，我們可能會問的第一個問題是，我們希望它成為一個什麼樣的插件？

Do we want it to be an audio effect?

我們希望它是一種音頻效果嗎？

Do we want it to be a synthesizer?

我們希望它是一個合成器嗎？

Do we want it to be some type of midi effect?

我們希望它是某種類型的 midi 效果嗎？

These are some of the first questions that we would ask ourselves, right?

這些都是我們首先會問自己的問題，對嗎？

And so this is what I would call or what would technically be called global configuration.

這就是我所說的或技術上所說的全局配置。

Okay, what do we want this project to be?

好吧，我們希望這個項目成為什麼？

So you can see that here with the CMake file that these global configurations are here on the front, meaning on the CMake file itself, that we can change these to true or false.

在 CMake 文件中，你可以看到這些全局配置都在前面，也就是 CMake 文件本身，我們可以將其改為 true 或 false。

So think of these as options or buttons that we could switch as developers.

是以，可以把它們看作是我們作為開發人員可以切換的選項或按鈕。

Now, what happens is that these actually affect what happens on the code in the project that's actually generated.

現在的情況是，這些代碼實際上會影響項目中實際生成的代碼。

So if we go to skipping ahead a little bit into some of the functions into the plugin processor.cpp, we have this function here that says accepts midi, right?

是以，如果我們跳過插件處理器.cpp 中的一些函數，就會發現這裡有一個接受 midi 的函數，對嗎？

And we can see that this is currently set to return false, okay?

我們可以看到目前的設置是返回 false，好嗎？

Because we see that this return true is kind of shaded and that it's currently returning false.

因為我們看到這個返回值為 true 的地方有陰影，目前返回的是 false。

So it's saying that we do not want midi input.

也就是說，我們不需要 midi 輸入。

That correlates directly with what we have here.

這與我們這裡的情況直接相關。

This option needs midi input.

該選項需要 midi 輸入。

Now, if I set this to true, and then if I regenerate the CMake file, rerun the CMake file, for people who are not using CLion, you would need to use the CMake command, which I believe is CMake-B, builds-G, and then whatever IDE that you're using.

如果我將此設置為 "true"，然後重新生成 CMake 文件，重新運行 CMake 文件，那麼對於不使用 CLion 的用戶來說，就需要使用 CMake 命令，我認為是 CMake-B、builds-G，然後是你正在使用的 IDE。

Okay, so now we come in here into access midi, and we see that that has now returned true.

好的，現在我們進入 access midi，可以看到返回值為 true。

So we've just kind of hit a button or hit a switch there, and that has actually switched things.

是以，我們只是按了一下按鈕或開關，實際上就改變了情況。

So this is a great way for us to be able to create a convenient interface for the developer to be able to change their configuration of their plugin or of their project in a way that before they actually even generate the project.

是以，這是一個很好的方法，我們可以為開發人員創建一個方便的界面，讓他們在實際生成項目之前，就能更改其插件或項目的配置。

So that is what the intention of using CMake really is, okay?

這就是使用 CMake 的真正目的，好嗎？

So if I take this and I turn this back to false, and then if I come here over back over here into this, and then I hit this refresh my CMake file, you'll see that this will change back to false.

所以，如果我把這個調回 false，然後回到這裡，再點擊這個刷新 CMake 文件，你就會看到這個會變回 false。

Okay, and see how that switched?

好吧，你看這是怎麼轉換的？

Okay, so that was something that was very simple, but also a very big revelation for me.

好吧，這件事很簡單，但對我來說也是一個很大的啟示。

Now, I know what some of you are thinking.

我知道你們有些人在想什麼。

Josh, why can't you just put this option directly in the header file or in the CPP file?

喬希，為什麼不能把這個選項直接放在頭文件或 CPP 文件中？

Why can't you just have some sort of option or some sort of bull that you put in here?

為什麼你就不能在這裡設置一些選項或公牛呢？

And the reason is going back to that architectural question of, okay, these are what we would call global configurations, configurations of the project just as a whole, okay?

原因就在於我們又回到了架構問題上，好吧，這些就是我們所說的全局配置，也就是整個項目的配置，明白嗎？

And that from an architectural standpoint, it would make more sense to have these options within the CMake file, which is kind of the front interface for the entry point for the developer of what they want this project to be, rather than having it hidden in an individual header file or CPP file, okay?

從架構的角度來看，將這些選項放在 CMake 文件中更有意義，因為 CMake 文件是開發人員瞭解項目的入口，而不是將其隱藏在單獨的頭文件或 CPP 文件中，好嗎？

So that's the reason that it's done that way and why developers choose to do it.

是以，這就是這樣做的原因，也是開發人員選擇這樣做的原因。

So that, I hope, helps reveal some of the light or shed a little bit of light on why we use build systems like CMake and why we use these global configurations rather than putting them into the code themselves.

是以，我希望這能幫助我們揭示或闡明為什麼要使用 CMake 這樣的構建系統，以及為什麼要使用這些全局配置而不是將它們放在代碼中。

So I hope that was helpful for you.

希望這對你有所幫助。

Okay, moving along, here we are in our header file, which is the audio plugin audio processor, and this is inheriting from a juice audio processor.

好了，現在我們來到頭文件，這是音頻插件的音頻處理器，繼承自 juice 音頻處理器。

Now, we have a few pure virtual functions that we've been implementing here, and we can tell that they're pure virtual functions because they have this override keyword, okay?

現在，我們在這裡實現了幾個純虛擬函數，我們可以看出它們是純虛擬函數，因為它們有這個覆蓋關鍵字，好嗎？

That's how you know that it's pure virtual function.

這樣你就知道這是純粹的虛擬函數。

If we go over to the juice documentation, the way that you know that it's a virtual function is if the function has this equals zero after the function name, okay?

如果我們查看果汁文檔，知道這是一個虛擬函數的方法是，如果函數名後面有等號 0，好嗎？

So that's how you know that this is a function that if you're inheriting from an audio processor class, you need to provide implementations of each one of those functions, okay?

所以，如果你繼承了音頻處理器類，你就需要提供每個函數的實現，明白嗎？

I know that that's a general C++ thing, but I want to try to make this digestible for people who are just getting started, okay?

我知道這是 C++ 的一般特性，但我想讓剛入門的人也能理解，好嗎？

So be sure to check out pure virtual functions if you're not familiar with that concept.

是以，如果您不熟悉純虛函數的概念，請務必查看純虛函數。

Okay, so what we're going to do is give you a whistle stop tour of what the juice audio processor is and what each function does.

好了，接下來我們要做的就是給大家介紹一下果汁音頻處理器是什麼，以及每種功能的作用。

This is not going to be really comprehensive.

這並不全面。

This is going to be very general, but hopefully this should give you some insight into some things that you may not have known about before.

這篇文章很籠統，但希望能讓你瞭解一些以前可能不知道的事情。

I know that I've learned a lot in creating this tutorial, so hopefully it's helpful for you.

我知道，在編寫本教程的過程中，我學到了很多東西，希望對你有所幫助。

Okay, so let's get started.

好了，讓我們開始吧。

So the first thing that we have here is the constructor.

首先是構造函數。

So this is what's called when the plugin is first created.

是以，這是插件首次創建時的調用。

And what happens is that it creates this juice audio processor.

然後，它就會創建一個果汁音頻處理器。

And then in here is this piece of code with some macros that look intimidating at first, but if you break it down, you can see that it's not very intimidating at all, okay?

這裡有一段代碼，其中包含一些宏，乍一看很嚇人，但如果你把它分解一下，就會發現它一點也不嚇人，明白嗎？

So here we have these variables that we created with the CMakeLists.

是以，我們有了這些用 CMakeLists 創建的變量。

Let me go back to CMakeLists here very quickly.

讓我快速回到 CMakeLists。

So remember, we have these global configurations like needsMIDI input, needsMIDI output, and so on.

請記住，我們有這些全局配置，如 needsMIDI 輸入、needsMIDI 輸出等。

So that's all these are here, okay?

就這些了，好嗎？

So it's just using those configurations to see if it's a MIDI effect or if it's a synth.

是以，它只是利用這些配置來確定是 MIDI 效果還是合成器。

And depending on what these choices are, then it's going to create some inputs and outputs and give those to our audio processor to create our audio output and input, right?

根據這些選擇，它將創建一些輸入和輸出，並將這些輸入和輸出交給音頻處理器，以創建音頻輸出和輸入，對嗎？

So if it's not a MIDI effect, right?

如果不是 MIDI 效果，對嗎？

So MIDI effect would take MIDI input and do something with it.

是以，MIDI 效果可以接收 MIDI 輸入，並對其進行處理。

So if it's not a MIDI effect, and if it's not a synth, then it's saying that we want an audio input that would create stereo input, okay?

是以，如果它不是 MIDI 效果器，也不是合成器，那麼它就是說，我們需要一個音頻輸入，以創建立體聲輸入，明白嗎？

And that if we wanted a stereo output, that that's what would happen.

如果我們想要立體聲輸出，就必須這樣做。

So if it's a MIDI effect, obviously you would want it to have a MIDI output.

是以，如果是 MIDI 效果器，顯然就需要有 MIDI 輸出。

But if it's not a MIDI effect, then you would want it to have an audio output.

但如果它不是 MIDI 效果器，就需要有音頻輸出。

So that's what's happening there is just creating your inputs and outputs for your plugin.

是以，這就是為插件創建輸入和輸出的過程。

And then of course, here in this function, this constructor function, you would have any type of initialization code that you would need to start up other classes, to start up other things that need to be initialized with some variables.

當然，在這個函數，這個構造函數中，你還會有任何類型的初始化代碼，用來啟動其他類，啟動其他需要初始化變量的東西。

Next, we have our destructor.

接下來是析構函數。

So this is typically what we would use that on destruction of this audio processor, which would typically be when somebody deletes your plugin, then this destructor would clear out any, you would use that to clear out any memory, any resources, any processes that need to be done before your plugin can be destroyed.

是以，我們通常會在銷燬音頻處理器時使用這個析構函數，一般來說，當有人刪除你的插件時，這個析構函數就會清空所有內存、資源和插件銷燬前需要完成的進程。

Things like that would typically happen here.

這樣的事情通常會發生在這裡。

These next ones, get name, accepts MIDI, produces MIDI, is MIDI effect.

接下來的這些功能包括獲取名稱、接受 MIDI、產生 MIDI 和 MIDI 效果。

All of those are direct correlations to those global configurations that we created here in the CMake file.

所有這些都與我們在 CMake 文件中創建的全局配置直接相關。

Needs MIDI input, needs MIDI output, and is MIDI effect and so on.

需要 MIDI 輸入、MIDI 輸出、MIDI 效果等等。

Okay, so going down a little bit further, we have this get tail length seconds.

好了，再往下一點，我們就能得到尾長秒數了。

So sometimes when you're using a plugin in a DAW, when you stop processing audio through the plugin, when you stop the DAW, then typically sometimes if it's like a reverb or it's the delay, maybe you want that delay or that reverb to continue ringing out until it's finished, until it reaches silence.

是以，有時當你在 DAW 中使用插件時，當你停止通過插件處理音頻時，當你停止 DAW 時，通常有時如果是混響或延時，也許你希望延時或混響繼續響起，直到結束，直到達到靜音。

Sometimes you want the audio to stop right away when your plugin is stopped.

有時，您希望在插件停止時立即停止音頻。

Okay, so if you want it to stop right away, then you would just leave that at 0.0 seconds.

好吧，如果你想讓它立即停止，那就把它停留在 0.0 秒。

That means that even if it's a delay plugin or a reverb plugin, that when you hit stop, that the delay or the reverb stops.

這意味著，即使是延時插件或混響插件，當你按下停止鍵時，延時或混響也會停止。

If you want it to continue playing after audio is done processing through the effect, after you've stopped the DAW, then you would change this to a different number.

如果您想讓它在音頻通過效果器處理完畢、DAW 停止後繼續播放，則需要將其改為不同的數字。

These next few functions like get num programs, get current program, set current program, get current program name, change program name, all of these are referring to presets.

接下來的幾個功能，如獲取編號程序、獲取當前程序、設置當前程序、獲取當前程序名稱、更改程序名稱，都是指預置。

So this is referring to a preset if it's loaded or if you want to get what the preset name is.

是以，如果預設已加載，或者你想知道預設的名稱，這裡指的就是預設。

So typically your presets will be stored in some type of a vector with what you want each parameter to be set at, and that's how that would be stored.

是以，通常情況下，您的預設會存儲在某種類型的矢量中，其中包含您希望設置的每個參數，這就是存儲方式。

And so all of these are just referring to loading them, getting them, changing the name of your plugin, of your preset rather, and so on.

所有這些都是指加載它們、獲取它們、更改插件名稱、預設名稱等等。

Going down a little bit further, we have this function called prepare to play.

再往下一點，我們有一個名為 "準備播放 "的函數。

So this is one of the more important functions that you have here in the audio processor.

是以，這是音頻處理器中最重要的功能之一。

It's probably one of the top two or three most important functions.

這可能是最重要的兩三個功能之一。

So anytime that you're processing a, you're doing some type of digital signal processing, so let's say that you have a reverb or you have a delay and you've created an algorithm or you're sourcing an algorithm from somewhere, typically you'll have some type of function that's called either prepare or reset or prepare to play.

是以，無論何時，只要你在處理數字信號處理，比方說，你有一個混響或延遲，你創建了一個算法，或者你從某個地方獲取了一個算法，通常你會有某種類型的函數，被稱為準備、重置或準備播放。

And what this does is it allows you to take the sample rate and the buffer size of where the DA, of what the DAW is processing and pass it into these individual algorithms.

這樣做的目的是，讓你可以將採樣率和數字音頻處理器處理的緩衝區大小，傳遞到這些單獨的算法中。

Okay, so for example, let's say that we have a one second delay algorithm, right?

好吧，舉個例子，假設我們有一個一秒延遲算法，對嗎？

So your delay algorithm needs to know whether the sample rate is 44,100 samples per second or 48,000 samples per second, because that will determine whether that delay algorithm needs to process 44,100 samples or 48,000 samples to create that delay accurately.

是以，你的延遲算法需要知道採樣率是每秒 44,100 個採樣點還是每秒 48,000 個採樣點，因為這將決定延遲算法需要處理 44,100 個採樣點還是 48,000 個採樣點才能準確創建延遲。

Okay, so that's why any DSP algorithm, typically you'll need some sort of prepare or reset or prepare to play algorithm that is implemented here in prepare to play.

好了，這就是為什麼任何 DSP 算法，通常都需要某種準備、重置或準備播放算法，而準備播放算法就在這裡實現。

Now, another thing is to think about or to know about is when this function is actually called within the plugin.

現在，另一件需要考慮或瞭解的事情是，何時在插件中實際調用這個函數。

So depending on the DAW, sometimes these are called at different times, but typically what'll happen is that when you create a plugin in your DAW, it will, I think most of them, all of them perhaps call prepare to play when the the plugin is getting ready to start processing audio again.

是以，根據 DAW 的不同，有時會在不同的時間調用這些功能，但通常情況下，當你在 DAW 中創建一個插件時，我想大多數插件都會調用 "準備播放 "功能，也許所有插件都會在插件準備再次開始處理音頻時調用 "準備播放 "功能。

So for example, when the user hits the space bar to start playing audio through the plugin.

例如，當用戶點擊空格鍵開始通過插件播放音頻時。

So let's say, and the reason for this is, let's say that the user has been playing audio through the plugin and the sample rate is 44,100 and they've been playing audio through the plugin and then they stop it.

假設用戶一直通過插件播放音頻，採樣率為 44100，然後他們停止了播放。

Let's say for whatever reason, they decide to change the sample rate to 48,000 samples per second.

比方說，不管出於什麼原因，他們決定將採樣率改為每秒 48,000 個採樣點。