Fade Through Gray — effect skill for transitions

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A drains to black-and-white, crossfades to B in gray, and B regains its colour.

What it does

Colour leaves the frame, the two shots blend in monochrome, colour comes back on the new one.

When: Flashbacks, memories, moving from past to present.

Watch out: Using it between two shots that are already low-saturation; nobody sees it.

Timing: 0.8–1.2 s.

Also called: Desaturate fade, Memory fade

In FFmpeg

Both inputs need the same size, frame rate, timebase, SAR and pixel format (settb=AVTB fixes the timebase error that fps alone leaves). offset is where the transition starts on the first clip's timeline (its length minus the overlap).

ffmpeg -i a.mp4 -i b.mp4 -filter_complex \
 "[0:v]fps=30,scale=1920:1080,setsar=1,settb=AVTB,format=yuv420p[a];[1:v]fps=30,scale=1920:1080,setsar=1,settb=AVTB,format=yuv420p[b];\
  [a][b]xfade=transition=fadegrays:duration=0.5:offset=4.5[v];[0:a][1:a]acrossfade=d=0.5[a]" \
 -map "[v]" -map "[a]" out.mp4

In HyperFrames

Tween filter: saturate(1→0) on A and saturate(0→1) on B across a short opacity overlap.

Where this comes from

Use when

Not for

Install

Example output

https://s3.varg.ai/how-to/previews/8ee597135394/take-xfade-fade-grays.mp4 — fadegrays between two shots, with the timeline strip of the edit. Footage: Charge (2022), Blender Studio | studio.blender.org, CC BY 4.0; Tears of Steel (2012), (CC) Blender Foundation | mango.blender.org, CC BY 3.0. (credit: Rendered by varg · Charge (2022) + Tears of Steel (2012))

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