# How to react on VST3 Bypass **URL:** \ **Category:** Uncategorized\ **Created:** [9 March 2021 08:35 UTC](https://iplug2.discourse.group/t/how-to-react-on-vst3-bypass/337 "2021-03-09T08:35:45Z")\ **Posts on this page:** 16\ **Page:** 1
**Author:** ![ToneSpotter](https://yyz2.discourse-cdn.com/free1/user_avatar/iplug2.discourse.group/tonespotter/32/148_2.png) [@ToneSpotter](https://iplug2.discourse.group/u/ToneSpotter)\ **Post date:** [9 March 2021 08:35 UTC](https://iplug2.discourse.group/t/how-to-react-on-vst3-bypass/337/1 "2021-03-09T08:35:45Z")
Hi, I want to connect my own bypass procedures to the VST3 bypass state. I’ve found the Get/SetBypassed() method in IPlugVST3ProcessorBase, but this seems not what I need. I want something like a “normal” IParam, to which I can connect to change the behavior of my plugin. Is it possible without digging in VST3 code? Any idea? Thank you in advance! Hermann ---
**Author:** ![vasyan](https://yyz2.discourse-cdn.com/free1/user_avatar/iplug2.discourse.group/vasyan/32/82_2.png) [@vasyan](https://iplug2.discourse.group/u/vasyan)\ **Post date:** [9 March 2021 10:15 UTC](https://iplug2.discourse.group/t/how-to-react-on-vst3-bypass/337/2 "2021-03-09T10:15:55Z")
My solution to this: ``` #if IPLUG_DSP void AmbientReverb::ProcessBlock(sample **inputs, sample** outputs, int nFrames) { const int nChans = NOutChansConnected(); if (GetBypassed()) { for (int s = 0; s < nFrames; ++s) { for (int c = 0; c < nChans; ++c) { outputs[c][s] = inputs[c][s]; } } } else fReverb.ProcessBlock(inputs, outputs, nFrames, nChans); } #endif ``` ---
**Author:** ![ToneSpotter](https://yyz2.discourse-cdn.com/free1/user_avatar/iplug2.discourse.group/tonespotter/32/148_2.png) [@ToneSpotter](https://iplug2.discourse.group/u/ToneSpotter)\ **Post date:** [9 March 2021 10:50 UTC](https://iplug2.discourse.group/t/how-to-react-on-vst3-bypass/337/3 "2021-03-09T10:50:18Z")
Great idea, but ProcessBlock isn’t called, if the bypass is enabled… So we first must ensure. that this happens. ---
**Author:** ![ToneSpotter](https://yyz2.discourse-cdn.com/free1/user_avatar/iplug2.discourse.group/tonespotter/32/148_2.png) [@ToneSpotter](https://iplug2.discourse.group/u/ToneSpotter)\ **Post date:** [9 March 2021 11:03 UTC](https://iplug2.discourse.group/t/how-to-react-on-vst3-bypass/337/4 "2021-03-09T11:03:34Z")
Hi vasyan, I’ve just looked at your “Chorus GAS” VST3 plugin and you managed to ignore the hosts Bypass switch. What did you do for this? Thanks! ---
**Author:** ![vasyan](https://yyz2.discourse-cdn.com/free1/user_avatar/iplug2.discourse.group/vasyan/32/82_2.png) [@vasyan](https://iplug2.discourse.group/u/vasyan)\ **Post date:** [9 March 2021 11:16 UTC](https://iplug2.discourse.group/t/how-to-react-on-vst3-bypass/337/5 "2021-03-09T11:16:08Z")
This plugin does not provide a bypass at all. Believe me, the traversal should be done by the host and not by the plugin. All modern DAWs have a plugin bypass function. Therefore, I do not consider it necessary to duplicate this function with a plugin. ---
**Author:** ![ToneSpotter](https://yyz2.discourse-cdn.com/free1/user_avatar/iplug2.discourse.group/tonespotter/32/148_2.png) [@ToneSpotter](https://iplug2.discourse.group/u/ToneSpotter)\ **Post date:** [9 March 2021 11:17 UTC](https://iplug2.discourse.group/t/how-to-react-on-vst3-bypass/337/6 "2021-03-09T11:17:07Z")
Debugging helps… In case of GetBypassed() == true, IPlugVST3ProcessorBase::ProcessAudio() calls PassThroughBuffers() instead of ProcessBuffers(). As this is not a virtual method, I can not overwrite PassThroughBuffers()… ---
**Author:** ![ToneSpotter](https://yyz2.discourse-cdn.com/free1/user_avatar/iplug2.discourse.group/tonespotter/32/148_2.png) [@ToneSpotter](https://iplug2.discourse.group/u/ToneSpotter)\ **Post date:** [9 March 2021 11:19 UTC](https://iplug2.discourse.group/t/how-to-react-on-vst3-bypass/337/7 "2021-03-09T11:19:43Z")
Oh, if you have a latency in you DSP algorithm it makes sense to ensure a click free bypass. Most of the plugins I examined react on host bypass and I want to do it also… EDIT: latency corrected bypass is done by iPlug2 itself. This helps a little… ---
**Author:** ![vasyan](https://yyz2.discourse-cdn.com/free1/user_avatar/iplug2.discourse.group/vasyan/32/82_2.png) [@vasyan](https://iplug2.discourse.group/u/vasyan)\ **Post date:** [9 March 2021 11:20 UTC](https://iplug2.discourse.group/t/how-to-react-on-vst3-bypass/337/8 "2021-03-09T11:20:14Z")
> [@ToneSpotter](#): > > I’ve just looked at your “Chorus GAS” VST3 plugin and you managed to ignore the hosts Bypass switch. There is nothing special here. P.S. Since I have been programming in Delphi for a very long time, I have a habit of using Pascal identifiers to designate classes and their fields. 😉 ``` #if IPLUG_DSP void TChorusGAS::ProcessBlock(sample **inputs, sample** outputs, int nFrames) { const int nChans = NOutChansConnected(); fBands->ProcessBlock(inputs, outputs, nFrames, nChans); } #endif ``` ---
**Author:** ![ToneSpotter](https://yyz2.discourse-cdn.com/free1/user_avatar/iplug2.discourse.group/tonespotter/32/148_2.png) [@ToneSpotter](https://iplug2.discourse.group/u/ToneSpotter)\ **Post date:** [9 March 2021 12:48 UTC](https://iplug2.discourse.group/t/how-to-react-on-vst3-bypass/337/9 "2021-03-09T12:48:47Z")
Still open and when I am more precise: I want to couple the host Bypass mode with my own Bypass toggle switch. ---
**Author:** ![vasyan](https://yyz2.discourse-cdn.com/free1/user_avatar/iplug2.discourse.group/vasyan/32/82_2.png) [@vasyan](https://iplug2.discourse.group/u/vasyan)\ **Post date:** [10 March 2021 03:01 UTC](https://iplug2.discourse.group/t/how-to-react-on-vst3-bypass/337/10 "2021-03-10T03:01:05Z")
``` bool Bypass; ... void Effect::ProcessBlock(sample **inputs, sample** outputs, int nFrames) { const int nChans = NOutChansConnected(); if (Bypass) { for (int s = 0; s < nFrames; ++s) { for (int c = 0; c < nChans; ++c) { outputs[c][s] = inputs[c][s]; } } } else { // Effect implementation } } ``` ---
**Author:** ![ToneSpotter](https://yyz2.discourse-cdn.com/free1/user_avatar/iplug2.discourse.group/tonespotter/32/148_2.png) [@ToneSpotter](https://iplug2.discourse.group/u/ToneSpotter)\ **Post date:** [10 March 2021 07:32 UTC](https://iplug2.discourse.group/t/how-to-react-on-vst3-bypass/337/11 "2021-03-10T07:32:40Z")
Sorry, you misunderstood me. Most of the VST3 plugins I have installed have a Bypass Button, which is linked to the hosts Bypass mode. Here an example, TDR Nova: ![Screenshot 2021-03-10 082343](https://global.discourse-cdn.com/free1/uploads/iplug2/original/1X/71d6e8742152a4cf5774e8594e86c0d7c89e4285.png) You see in the upper left corner the bypass switch of Studio One and in the lower right corner the bypass switch of TDR Nova. This is what I want. (TDR Nova was written using JUCE, but I hoped this would also possible with iPlug2 without forking my own version…) Beside this: your bypass solution will have problems if latency \> 0 and even the latency corrected version of iPlug2 results in audible clicks, as it jumps from the DSP output to the original signal. In my DSP code I have already a click free version which blends smoothly between these two states and therefore I want iPlug2 to use my version of ProcessBlock() when host bypass is enabled. ---
**Author:** ![ToneSpotter](https://yyz2.discourse-cdn.com/free1/user_avatar/iplug2.discourse.group/tonespotter/32/148_2.png) [@ToneSpotter](https://iplug2.discourse.group/u/ToneSpotter)\ **Post date:** [11 March 2021 06:12 UTC](https://iplug2.discourse.group/t/how-to-react-on-vst3-bypass/337/12 "2021-03-11T06:12:42Z")
For the problem of calling `ProcessBlock()`, when Bypass is enabled, I’ve created a small patch. I will create a merge request for this later. ---
**Author:** ![ToneSpotter](https://yyz2.discourse-cdn.com/free1/user_avatar/iplug2.discourse.group/tonespotter/32/148_2.png) [@ToneSpotter](https://iplug2.discourse.group/u/ToneSpotter)\ **Post date:** [11 March 2021 13:14 UTC](https://iplug2.discourse.group/t/how-to-react-on-vst3-bypass/337/13 "2021-03-11T13:14:15Z")
Linking the bypass states is a little bit more complicated. My solution: In my bypass control I define: ```auto void BypassSchalter::OnMouseDown(float x, float y, const IMouseMod& mod) { double new_state = (GetValue() < 0.5 ? 1.0 : 0.0); SetValue(new_state); SetDirty(true); #ifdef VST3_API IPlugVST3* p = dynamic_cast(GetDelegate()); if (p != nullptr) { p->BeginInformHostOfParamChange(kBypassParam); p->InformHostOfParamChange(kBypassParam, new_state); p->EndInformHostOfParamChange(kBypassParam); while (p->GetBypassed() != new_state) { // Sometimes the param change doesn't work (timimg?). Wait and try it again... std::this_thread::sleep_for(std::chrono::milliseconds(5)); p->BeginInformHostOfParamChange(kBypassParam); p->InformHostOfParamChange(kBypassParam, new_state); p->EndInformHostOfParamChange(kBypassParam); } } #endif } ``` I the DSP thread I define an ISender, which sends the current host bypass state to my bypass control: ```auto void Oberton::ProcessBlock(sample **inputs, sample** outputs, int nFrames) { bool bypass = (GetParam(kInternalBypass)->Value() > 0.5); #ifdef VST3_API if (bypass != GetBypassed()) { bypass = GetBypassed(); mBypassData.vals[0] = (bypass ? 1.0 : 0.0); mBypassSender.PushData(mBypassData); } #endif // DPS code, which respects the bypass variable } ``` A little complicated, but I see no other way, Has someone other ideas? Btw. here the patch for iPlug2, which I mentioned in the previous post: ```diff diff --git a/IPlug/IPlugProcessor.h b/IPlug/IPlugProcessor.h index afc0e10a4..7779261e7 100644 --- a/IPlug/IPlugProcessor.h +++ b/IPlug/IPlugProcessor.h @@ -112,8 +112,11 @@ public: /** @return \c true if the plugin is currently bypassed*/ bool GetBypassed() const { return mBypassed; } + /** @return \c true if ProcessBlock should be called even if the plugin is currently bypassed*/ + bool GetProcessIfBypassed() const { return mProcessIfBypassed; } + /** @return \c true if the plugin is currently rendering off-line */ - bool GetRenderingOffline() const { return mRenderingOffline; }; + bool GetRenderingOffline() const { return mRenderingOffline; } #pragma mark - /** @return The number of samples elapsed since start of project timeline. */ @@ -264,6 +267,7 @@ protected: void SetSampleRate(double sampleRate) { mSampleRate = sampleRate; } void SetBlockSize(int blockSize); void SetBypassed(bool bypassed) { mBypassed = bypassed; } + void SetProcessIfBypassed(bool process) { mProcessIfBypassed = process; } void SetTimeInfo(const ITimeInfo& timeInfo) { mTimeInfo = timeInfo; } void SetRenderingOffline(bool renderingOffline) { mRenderingOffline = renderingOffline; } const WDL_String& GetChannelLabel(ERoute direction, int idx) { return mChannelData[direction].Get(idx)->mLabel; } @@ -287,6 +291,8 @@ private: int mTailSize = 0; /** \c true if the plug-in is bypassed */ bool mBypassed = false; + /** \c true if the plug-in should call ProcessBlock even if bypassed */ + bool mProcessIfBypassed = false; /** \c true if the plug-in is rendering off-line*/ bool mRenderingOffline = false; /** A list of IOConfig structures populated by ParseChannelIOStr in the IPlugProcessor constructor */ diff --git a/IPlug/VST3/IPlugVST3_ProcessorBase.cpp b/IPlug/VST3/IPlugVST3_ProcessorBase.cpp index 56267d38a..dbd3f99ec 100644 --- a/IPlug/VST3/IPlugVST3_ProcessorBase.cpp +++ b/IPlug/VST3/IPlugVST3_ProcessorBase.cpp @@ -398,7 +398,7 @@ void IPlugVST3ProcessorBase::ProcessAudio(ProcessData& data, ProcessSetup& setup chanOffset += busChannels; } - if (GetBypassed()) + if (GetBypassed() && !GetProcessIfBypassed()) { if (sampleSize == kSample32) PassThroughBuffers(0.f, data.numSamples); // single precision ``` ---
**Author:** ![TBProAudio](https://yyz2.discourse-cdn.com/free1/user_avatar/iplug2.discourse.group/tbproaudio/32/111_2.png) [@TBProAudio](https://iplug2.discourse.group/u/TBProAudio)\ **Post date:** [12 March 2021 15:09 UTC](https://iplug2.discourse.group/t/how-to-react-on-vst3-bypass/337/14 "2021-03-12T15:09:04Z")
Patching is the best and most reliable solution. Maybe some does a CR? IPlugProcessor.h: > bool bcanhandlebypass=false; > SetCanHandleByPass(bool state){bcanhandlebypass = \_state;} > GetCanHandleByPass(void){return bcanhandlebypass;} each plugin api, process: > if (GetBypassed() && !GetCanHandleByPass()) > PassThroughBuffers(…) > else > ProcessBuffers(…) ---
**Author:** ![ToneSpotter](https://yyz2.discourse-cdn.com/free1/user_avatar/iplug2.discourse.group/tonespotter/32/148_2.png) [@ToneSpotter](https://iplug2.discourse.group/u/ToneSpotter)\ **Post date:** [12 March 2021 17:58 UTC](https://iplug2.discourse.group/t/how-to-react-on-vst3-bypass/337/15 "2021-03-12T17:58:18Z")
I will create a PR next week… ---
**Author:** ![ToneSpotter](https://yyz2.discourse-cdn.com/free1/user_avatar/iplug2.discourse.group/tonespotter/32/148_2.png) [@ToneSpotter](https://iplug2.discourse.group/u/ToneSpotter)\ **Post date:** [25 March 2021 08:53 UTC](https://iplug2.discourse.group/t/how-to-react-on-vst3-bypass/337/16 "2021-03-25T08:53:44Z")
After reading the VST3 documentation I realized, that the problem is in iPlug2 itself, as it defines it’s own bypass parameter. I patched the VST3 part, added a new IParam flag IParam::kFlagBypass and now I can use a “normal” IParam as bypass. This also switches off the GetBypassed() logic of iPlug2, so all is fine for me. ```auto diff --git a/IPlug/IPlugParameter.h b/IPlug/IPlugParameter.h index 1ed0c9205..b8141a7cc 100644 --- a/IPlug/IPlugParameter.h +++ b/IPlug/IPlugParameter.h @@ -55,6 +55,8 @@ public: kFlagSignDisplay = 0x8, /** Indicates that the parameter may influence the state of other parameters */ kFlagMeta = 0x10, + /** Indicates that the parameter may act as host bypass parameter */ + kFlagBypass = 0x20, }; /** DisplayFunc allows custom parameter display functions, defined by a lambda matching this signature */ @@ -470,7 +472,10 @@ public: /** @return \c true If the parameter is flagged as a "meta" parameter, e.g. one that could modify other parameters */ bool GetMeta() const { return mFlags & kFlagMeta; } - /** Get a JSON description of the parameter. + /** @return \c true If the parameter may act as host bypass parameter */ + bool GetHandlesBypass() const { return mFlags & kFlagBypass; } + + /** Get a JSON description of the parameter. * @param json WDL_String to fill with the JSON * @param idx Index of the parameter, to place in the JSON */ void GetJSON(WDL_String& json, int idx) const; diff --git a/IPlug/VST3/IPlugVST3_ControllerBase.h b/IPlug/VST3/IPlugVST3_ControllerBase.h index 90ded4eb8..d4362439e 100644 --- a/IPlug/VST3/IPlugVST3_ControllerBase.h +++ b/IPlug/VST3/IPlugVST3_ControllerBase.h @@ -76,10 +76,22 @@ public: } else #endif - unitInfo.programListId = Steinberg::Vst::kNoProgramListId; - - if (!plugIsInstrument) - mParameters.addParameter(mBypassParameter = new IPlugVST3BypassParameter()); + unitInfo.programListId = Steinberg::Vst::kNoProgramListId; + + if (!plugIsInstrument) { + bool existsBypassParameter = false; + for (int i = 0; i < pPlug->NParams() && !existsBypassParameter; i++) + { + if (pPlug->GetParam(i)->GetHandlesBypass()) + { + existsBypassParameter = true; + } + } + + if (!existsBypassParameter) { + mParameters.addParameter(mBypassParameter = new IPlugVST3BypassParameter()); + } + } pEditController->addUnit(new Steinberg::Vst::Unit(unitInfo)); diff --git a/IPlug/VST3/IPlugVST3_Parameter.h b/IPlug/VST3/IPlugVST3_Parameter.h index a7158b34b..71b312263 100644 --- a/IPlug/VST3/IPlugVST3_Parameter.h +++ b/IPlug/VST3/IPlugVST3_Parameter.h @@ -39,6 +39,7 @@ public: if (pParam->GetCanAutomate()) flags |= Steinberg::Vst::ParameterInfo::kCanAutomate; if (pParam->Type() == IParam::kTypeEnum) flags |= Steinberg::Vst::ParameterInfo::kIsList; + if (pParam->GetHandlesBypass()) flags |= Steinberg::Vst::ParameterInfo::kIsBypass; info.defaultNormalizedValue = valueNormalized = pParam->ToNormalized(pParam->GetDefault()); info.flags = flags; ``` This is only for VST3… To use, just write: `GetParam(kBypass)->InitBool("Bypass", false, "", IParam::kFlagBypass);`