Eternal2x

Smooth 2x for hand-drawn animation, inside DaVinci Resolve Studio.

Anime is drawn on 2s or 3s: the artist draws twelve pictures a second and each one is held for two or three frames to fill 24fps. That is why anime looks stepped when you slow it down, and why running it straight through a frame interpolator does nothing useful. Most neighbouring frames are identical, so there is no motion to interpolate between them.

Eternal2x recovers the real drawings first, then rebuilds the shot.

source     A A B B C C C D D        9 frames, held on 2s
drawings   A   B   C     D          4 unique drawings
rebuilt    A a B b C C c D D        in-betweens generated, C keeps its longer hold

Every drawing starts on the same frame it did in the source, so cuts and lip sync stay where the edit put them.

The result has the same length and frame rate as the clip you started with, so it drops straight back into your edit.

What it does

• Finds duplicated frames and works out whether the clip is on 1s, 2s or 3s.
• Rebuilds the motion with optical flow, generating the in-between frames that were never drawn.
• Keeps deliberate held poses still, instead of smearing them into drift.
• Cuts stay hard. Blending across a scene change would show both shots at once, so it snaps instead.
• Upscales 2x using Resolve's Super Scale.

It works like Twixtor without the warping. Where forward and backward motion disagree, which is where optical flow normally tears, it fades to a soft dissolve rather than inventing a broken frame.

Requirements

• DaVinci Resolve Studio 18 or newer. Super Scale and Optical Flow are Studio features, so the free edition cannot do the upscale. Eternal2x detects it and tells you rather than silently skipping it.
• Python 3.8+ on your PATH, from python.org.

Install

With the installer window

1. Extract the download somewhere permanent.
2. From inside the extracted folder, run python Installer/gui_installer.py (python3 on macOS) and click Install.
3. It installs numpy and opencv-python, copies the plugin into Resolve's scripts folder and writes the config.
4. Restart Resolve and open Workspace → Scripts → Eternal2x.

If the window does not open, your Python was built without Tk. Use the manual install below, which does the same job.

Manual

pip install numpy opencv-python
python Installer/install_eternal2x.py

Then restart Resolve.

The installer writes to Resolve's Utility scripts folder, which Resolve lists under Workspace → Scripts on every page:

• Windows: %APPDATA%\Blackmagic Design\DaVinci Resolve\Support\Fusion\Scripts\Utility\
• macOS: ~/Library/Application Support/Blackmagic Design/DaVinci Resolve/Fusion/Scripts/Utility/

Earlier versions used the Comp folder, which Resolve only lists on the Fusion page. Re-running the installer moves it.

The config records where the plugin folder is, so re-run the installer if you move it.

Using it

1. Select a clip on your timeline.
2. Open Workspace → Scripts → Eternal2x.
3. Click Analyse. It reads the clip and tells you what it found, for example 1438 frames, 719 unique drawings (719 held, 50%). Animated on 2s. Nothing is changed, so this is safe to run on anything.
4. Click Smooth Clip.

The render runs in the background and the panel shows progress, so Resolve stays usable while it works. When it finishes, the rebuilt clip is imported and added to the end of your timeline.

Eternal2x works on the clip's whole source file, not just the part trimmed onto your timeline, so trim the result to match once it is in.

Settings

Setting	What it does
Quality	Fast for a quick look, Better for normal work, Best tracks fine detail like eyes and fingers at the cost of speed.
Hold pattern	Leave on Auto detect. Force On 2s or On 3s if a clip has unusual timing that trips the detector.
Output	Image sequence is lossless and always imports. MP4 is a single compact file but lossy. AVI is a lossless single file that some Resolve builds will not import.
Upscale 2x	Applies Resolve's Super Scale to the imported clip.
Interpolate	Off means de-duplicate only, without generating in-betweens.

Settings are remembered between sessions.

What it will not do

If a clip has no duplicated frames, Eternal2x says so and stops. Live action and animation already on 1s have nothing to recover, and smoothing them would only invent motion that was never there.

From the command line

Every button is a thin wrapper around one module, so you can script it:

python -m Stages.resolve_smooth --video shot.mov --analyse
python -m Stages.resolve_smooth --video shot.mov --quality best --format mp4
python -m Stages.resolve_smooth --video shot.mov --base-hold 3 --no-interpolate

--video skips Resolve entirely and writes the result to an Eternal2x folder beside the source, or to --output-dir. The 2x upscale is Resolve's Super Scale, applied when the panel imports the result, so a --video run is always at source resolution and --no-upscale only matters inside Resolve.

Add --json and stdout carries a single JSON summary, errors included, while progress goes to stderr.

Updates

Eternal2x checks for updates at startup, or on demand with the Check for Updates button. Updates are verified against a SHA-256 checksum before being applied. Restart Resolve afterwards.

Troubleshooting

Problem	Fix
"Plugin folder not configured"	Re-run python Installer/install_eternal2x.py.
"Could not reach Resolve"	Open the panel from Workspace → Scripts, not from a terminal.
"No clip selected"	Click a clip on the timeline, then press Use Selected Clip.
Analyse says nothing to do	The clip has no duplicated frames. It is live action, or already on 1s.
Progress seems stuck	Press Refresh Progress. If a run was interrupted, press Reset.
Resolve would not import the render	The render still finished. The panel prints where it is, so drag it into your media pool. Switching Output to Image sequence avoids this.
Upscale skipped	Super Scale needs Resolve Studio.
Something else	Email the panel's status text and the .eternal2x_last_run.log file from the plugin folder.

Development

./test.sh

360+ tests, no Resolve required. The suite fakes the Resolve scripting API and runs the Lua panel under an embedded Lua runtime, so buttons, commands and the full render pipeline are all covered headlessly. See tests/README.md.

Tests run on Linux, macOS and Windows against Python 3.9 and 3.12.

To see which scripting API methods a Resolve build offers, turn on Preferences → System → General → External scripting using → Local, set up the environment variables from Blackmagic's scripting README, then run python -m Stages.resolve_probe from the plugin folder.

To cut a release, bump VERSION and push a matching tag:

git tag v0.3.1 && git push origin v0.3.1

The release workflow builds the archives, publishes them, checks the published downloads really resolve, and refreshes update/latest.json. The tag is derived from VERSION in one place, so the archives, the tag and the update feed cannot drift apart.

To build locally without publishing:

python Installer/build_release.py            # build the folders and zips
python Installer/build_release.py --publish  # build, tag, upload, verify
python Installer/build_release.py --verify   # check the live feed is sound

update/latest.json always describes the release that is live, so only --publish writes it, and only once the uploaded files match the build. A plain build never touches it. Files already on a release are never replaced. If you change anything that ships after a release goes out, bump VERSION and cut a new one rather than re-uploading.

Archives are byte reproducible, so rebuilding a tag on any machine gives the same checksums as the published ones.

Questions

Email Justlighttbusiness@gmail.com