View source for Real-time preview of effects

{{intro|Some types of effects in Audacity support ''real-time preview''. These types are: ''LADSPA, VST'', and ''Audio Unit'' effects.}}
Effects that support real-time preview are different from regular effects in the following ways:
* They can be opened when audio is playing or paused
* They can be opened even when no audio is selected
* The effect settings can be changed while audio is playing
* You can start and stop audio playback, change the selection, and solo or mute tracks while the effect dialog is open
* You will hear the effected track in the context of the mix
{{ednote| 
*'''Bill 04Jan2015:'''  [[ToDo-1]] We need a new image of the "control panel" of a VST effect in graphical mode. We may also want an example of a LADSPA effect in text mode. }}
When you open an effect that supports real-time preview it will have these buttons at the bottom of the effect dialog.
:[[Image:Real-time controls annotated.png]]
*&nbsp;<span title="Manage Effect button">[[Image:ManageEffectMenu.png|link=]]</span>&nbsp;'''Manage Effect menu:''' 
** '''User presets:''' If any user presets exist for this effect this menu will list them. Select one of the user presets to load it into the effect.
** '''Factory presets:''' If any factory presets exist for this effect this menu will list them. Select one of the factory presets to load it into the effect.
** '''Delete preset:''' Select this option to delete the currently-loaded user preset.
** '''Save as...''' Select this option to save the current settings as a user preset.
** '''Export...''' Select this option to export one or more presets (for sharing with other users or to move to another computer running the same effect).
** '''Import...''' Select this option to import a presets file.
** '''Options...''' Displays the options dialog for this type of effect. See the sections for each type of effect for a description of the options available.
*** [[Effect Menu#ladspa_options|LADSPA Options]]
*** [[Effect Menu#vst_options|VST Options]]
*** [[Effect Menu#au_options|Audio Unit Options]]
** '''About:''' Displays the effect type, effect name, version, vendor, and description.
*&nbsp;<span title="On/Off button">[[Image:BypassButton.png|link=]]</span>&nbsp;'''On/Off button:''' When this button is lit up (blue) the effect is on, otherwise the effect is off (inactive or bypassed). This is a convenient way to do a quick A/B comparison of how your project sounds with and without the effect.
*&nbsp;<span title="Play button in real-time preview effect">[[Image:RealTimePlayButton.png|link=]]</span>&nbsp;'''Play/Stop button:''' Click this button to begin playback. It changes to the Stop button&nbsp;<span title="Stop button in real-time preview effect">[[Image:RealTimeStopButton.png|link=]]</span>&nbsp;. Click it again to stop playback.
*&nbsp;<span title="Skip back button in real-time preview effect">[[Image:RealTimeSkipBackButton.png|link=]]</span>&nbsp;'''Skip Back button:''' When playback is stopped, clicking this button will move the playback cursor to the beginning of the track. During playback, each click of this button will perform a [[Playing and Recording#play_special|short seek back]].
*&nbsp;<span title="Skip forward button in real-time preview effect">[[Image:RealTimeSkipFwdButton.png|link=]]</span>&nbsp;'''Skip Forward button:''' When playback is stopped, clicking this button will move the playback cursor to the end of the track. During playback, each click of this button will perform a [[Playing and Recording#play_special|short seek forward]].
* '''Close button:''' Click this button to close the effect dialog.
* '''Apply button:''' Click this button to apply the effect to the selected audio. The effect dialog will remain open after the effect is applied. 
{{note|The ''Import'' and ''Export'' options behave differently for the different classes of effect that support them. See the appropriate sections below in the descriptions of each effect class. LADSPA effects do not support ''Import'' and ''Export''.
}}