FramePFX

A small (non-linear) video editor, written in C# using Avalonia for the UI

I mainly started this as a learning tool into the world of video/audio processing (all I really knew before this was basic OpenGL drawing), but also because other editors like vegas, premiere pro, hitfilm, etc, just seem to run so slowly and some of them just lack basic features (e.g zoom in the view port with CTRL + MouseWheel)

I doubt this will ever even come close to those editors, but hopefully it will at least support some basic editing

If you have any feedback/criticism for the app, that would be appreciate! Also feel free to contribute, if you would like to. You can see the TODO list near the bottom

New: Avalonia Remake

The primary version of the app is v2, which is the Avalonia remake (from WPF).

This version has new features that were not in the WPF edition, such as:

• You can drag around a video clip in the preview + there's better outline selection now that I understand transformation matrices better lol
• Slightly improved data parameter and property editor systems
• RateLimitedDispatchActions for spontaneous render requests (e.g. changing opacity parameter) to improve UI performance
• Tracks and Resource Tree Nodes can be moved around by dragging them

However, it seems like this remake is less responsive than the WPF counterpart unfortunately; you can feel a lag between dragging a clip and it being redrawn in the timeline, whereas in WPF it was almost unnoticeable

I hope to get this app back into the same state it was when using WPF and also improve upon it

Preview

This is the latest version using Avalonia:

Here is a preview of the export process. Export button is in File>Export, you specify a path and then click Export. To cancel the render you just click Cancel on the dialog behind the export progress window

The grey panel below "Exporter: FFmpeg" is encoder-specific details

Old previews from WPF

Here are some previews of features that aren't yet implemented, but that once were :)

This shows of some automation/animation/keyframe usage:

Automation/animation

Always found automating parameters in the standard editors to be generally finicky. Ableton Live has a really good automation editor though, so I took a fair bit of inspiration from it:

• Each clip has its own keyframe/envelope editor that stretches the entirety of the clip. Effects also use this
• Tracks have the same, but it stretches the entire timeline.
• Automating project settings, or anything else really, will soon be do-able on a timeline automation specific track (allowing for more than just video/audio tracks)

The clip's automation sequence editor's target parameter can be changed by selecting a row (I call them "slots") in the property editor. The currently selected slot is what the clip shows (if clip automation is visible, click C to toggle)

Rendering

Rendering uses SkiaSharp (for simplicity) and multiple render threads for speed. The RenderManager class handles the render initialisation.

The render phase is like this:

• Something tells the RenderManager that the render state is invalidated and to schedule a render on the app dispatcher
• All timeline tracks processed (bottom to top, as most editors do) to figure out if the track can be rendered (is it visible and a non-zero opacity and are there clips on the playhead that are visible)
• PrepareRenderFrame is called on the video tracks, which then calls PrepareRenderFrame on the clip being rendered. That method is used to generate rendering proxy data, such as the opacity of the clip at the current point in time
• A task is started, and that task calls the tracks' RenderFrame method, which calls the clips' RenderFrame method, which uses that proxy data (generated in the preparation phase) to actually draw pixels into the track's SKSurface
• Once all tracks have been rendered, the final frame is assembled from each track's SKSurface (on the rendering thread as well)
• The final frame is now completed, FrameRendered is fired in the render manager, and the view port hooks onto that event and draws the rendered frame

This is a simple but still performant rendering technique over say rendering all clips sequentially on the main thread (which is what I used to do). This may change in the future if I come up with a better system, but for now, it works pretty well

Resource list

The resources are shareable between clips, so that clips can obviously share similar details (e.g. same text or font/font size), or same image, same shape colour, etc.

To drag videos, images, etc., into the editor: drag and drop the file to the top left "resource manager panel", and then drag one of those items into the timeline

This system is still quite janky and, if anything, too flexible; added complexity for limiting the max number of resources referencable, and handling that error case

TODO

Avalonia Remake:

• Implement project settings dialog
• Implement UI for Effects list that can be dropped into a clip/track

Audio

I removed audio playback from the Avalonia remake because it required PortAudio, requiring a native project, both of which were a hassle to auto-compile. Check out the last WPF release for the issues on it though; it wasn't great

Automation Engine

• Add support for smooth interpolation (e.g. a curve between 2 key frames). I tried doing this, but had a hard time figuring out the math to do the interpolation, and also doing the hit testing for the UI

Clips

• AVMediaVideoClip is extremely slow for large resolution videos (e.g. 4K takes around 40ms to decode and render onscreen), and only a few video codecs even seem to work. Lots of common file formats give an error like "found invalid data while decoding". I don't know FFmpeg much but I hope to somehow fix this at some point
• Implement fading between 2 clips

Rendering

• I plan to use hardware acceleration for at least the final frame assembly because, at the moment, that is the most computationally expensive operation in the render phase right next to video decoding. I've added many optimisations to improve performance, such as render area feedback from clips so that the renderer only copies a known "effective" area of pixels instead of the whole frame from the track, but it's still quite slow, especially when using composition clips

History system

• There's no undo functionality yet. I might try and implement this once I implement a few of the other features like audio and maybe hardware accelerated final-frame assembly in the renderer

Bugs to fix

• Importing certain video files can cause the render to fail (some sort of "found invalid data while decoding" error)

Downloading and Compiling/Building

To compile and run the editor, you only require FFmpeg which you must download yourself. You can find the download link here: https://github.com/BtbN/FFmpeg-Builds/releases/download/latest/ffmpeg-master-latest-win64-gpl-shared.zip

FramePFX assumes everything is 64 bit --- x86/32-bit/AnyCPU most likely won't work!

Create a folder called libraries in the solution folder and a sub-folders called ffmpeg. Copy the contents of both of the ffmpeg archive into that folder. You should be able to navigate to \FramePFX\libraries\ffmpeg\lib.

If you only plan on debugging only from VS/Rider or whatever IDE you use, it works fine as long as the ffmpeg folder is in the 'libraries' folder. If you associated the fpfx file extension with FramePFX in the build folders, then you most likely will need to copy the DLL files in ffmpeg's bin folder (except for the .exe files) into the same folder as FramePFX.exe

Hopefully then you should be able to build and run without issue. This project uses Avalonia 11.2.2 and .NET 8 (C# 12)

Possible build problems

Sometimes, the SkiaSharp nuget library doesn't copy the skia library files to the bin folder when you clone this repo and built. There are 2 fixes I found:

• Copy \packages\SkiaSharp.2.88.7\runtimes\win-x64\native\libSkiaSharp.dll into the editor's bin folder.
• Or, delete the packages folder in the solution dir, then right-click the solution in visual studio and click "Clean Solution", then click Restore Nuget Packages, then rebuild all. If none of these work, try uninstalling SkiaSharp in the nuget manager and then reinstalling. If that still does not work, then I really don't know what's going on...

Contributing

Feel free to contribute whatever you want if you think it'll make the editor better! The code base isn't perfect so feel free to help try and standardize things

Licence

All source files in FramePFX are under the GNU General Public License version 3.0 or later (GPL v3.0+). FramePFX uses libraries that have other licences, such as MIT/LGPL licences.

If any source file is missing a copyright notice, it is assumed to be licenced under the same licence as FramePFX

Currently, the used LGPL parts are:

• FFmpeg.AutoGen, which is licenced under the GNU Lesser General Public License version 3.0 (LGPL v3.0)
• FFmpeg