A) Imported video had a different aspect ratio depending on how it was placed:
direct import used a uniform scale + center (preserve aspect), while the
asset-library timeline drag used an independent scale_x/scale_y (stretch to fill).
Add Transform::fit_centered (uniform scale, centered, aspect-preserving) and route
both paths through it, so a clip looks identical however it's added.
B) Exported video was stretched when the export resolution's aspect differed from
the document's (base_transform was always scale_non_uniform). Add
ExportFitMode {Stretch, Letterbox (default), Crop} on VideoExportSettings + a "Fit"
dropdown in advanced export settings, and a shared export_base_transform() helper:
Letterbox = uniform fit centered (black bars), Crop = uniform fill centered (trim),
Stretch = the old distort-to-fill. Threaded through the software, HDR, and
zero-copy export render paths (image export is doc-sized → identity).
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
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