Real-time preview of effects

Bill 11Dec2014: ToDo-1 Just getting a start on this. We may want to present this in a completely different way or in a different location.
Aside: this is going to be so much easier when all effects support real-time preview - no more special cases.

• Peter 16Dec14: This material was originally drafted on the Effect Menu page. However it would appear to fit better as its own page as this would give us the benefit of being able to link to this page for any effect that supports RTP.

  Bill wrote on the Effect Menu page: "As for moving stuff off this page, I can see moving Real-time Preview to its own page (which would need fleshing out with examples to make it worth while)".

Some classes of effects in Audacity support real-time preview. These classes 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

• ToDo-2 Bill 13Dec2014: Which looks better, plain or annotated?

  I've also reduced the size of the buttons images for use in-line with text.

• Peter 14Dec14: I prefer the annotated version.

When you open an effect that supports real-time preview it will have these buttons at the bottom of the effect dialog.

•   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 effect class. See the sections (below) for each effect class for a description of the options available for that effect class.
  • About: Displays the effect class, effect name, version, vendor, and description.
•   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.
•   Play/Stop button: Click this button to begin playback. It changes to the Stop button  . Click it again to stop playback.
•   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 short seek back.
•   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 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.

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.