Shared - Implement effects

[Joery-M]

Effects definition

This issue explains what 'effects' represent in the application.

Effects are modules that are added to timeline items (#257) to alter rendering and behavior of said items.

Effects can be grouped into the following groups:

• Transform
• Generate
• Transition
• Modify
• Audio
• Source

This list is subject to change with new features and should only be maintained as a baseline.

Effect types

Transform

This effect type transforms the existing image. For example moving the image to the right by 10 pixels.

Generate

This effect type generates an overlay on top of the existing image. For example:

• Text
• Outlines
• Fake lens flares

Transition

This effect type manages a transition between 2 timeline items. It should be visible on the timeline.
Examples:

• Cross-fade (audio and video)
• Slide
• Wipe

Modify

Name needs to change, this is very broad.

This effect type modifies the existing image or audio. So basically everything that doesn't fall into other categories.

Audio

This effect type specifically applies to audio, for example:

• Volume
• Normalize
• Panning
• Reverb

Source

This effect type generates the source data that will be used on the timeline item. There can only be 1 video source for each timeline item.
For video, the effect defines the base width and height and will provide the base image that will be used.
Examples:

• Media files
• SVG
• Static color
• External timeline
• Audio tone
• MIDI
• Subtitle file (VTT, SRT)
  For video, if there is no source to define width and height, the width and height of the current timeline should be used.

The source effect should also pass the following information to the timeline item:

• Source name
• Source type to be used for timeline colors
• Source duration
• (Video) Frame width and height

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Here is what this issue should implement:

• Source for static files (images)
• Source for chunked files (video, audio)
• Image transformation