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Overlays

Overlays are things you drop on top of a section that play across some or all of it. Three kinds:

  • Image — a PNG (with alpha) or JPEG, positioned somewhere on the frame
  • Audio — an MP3, WAV, FLAC, or similar, mixed with the section's video audio
  • Text — a string rendered with a system font, any size/colour

Every overlay has timing (start / duration), position (for image and text), and fade-in / fade-out controls.

Adding an overlay

  1. Build at least one section
  2. In the Add Clips panel, pick:
  3. OVERLAY on LAST section — for image or audio (ForgeAssembler sniffs the extension)
  4. TEXT on LAST section — for text
  5. Fill in the form that appears
  6. Click Add

The overlay shows up as a mini-list entry on the section card with a 🖼 / 🎵 / 📝 badge, a short preview, its timing, and a ✕ remove button.

Positions (image and text)

Nine named slots arranged in a 3×3 grid:

tl    tc    tr
ml  center  mr
bl    bc    br

All corner and edge slots use a 5%-of-frame breathing-room margin so content doesn't sit flush against the edge.

If you need pixel-perfect placement — build a transparent PNG at the size of your frame with the subject exactly where you want it, then drop the PNG on at center. This keeps the overlay vocabulary small.

Image overlays

Form fields:

  • File — path to the PNG/JPG (use 📁 Folder / 📄 File Browse)
  • Position — one of the nine slots
  • Opacity — 0–100%
  • Scale % — overlay width relative to frame width
  • Timing — start offset into the section, and duration (or "full section")
  • Fade in / fade out — seconds

Transparent PNGs work cleanly — the alpha channel is preserved through the scale filter.

Audio overlays

Form fields:

  • File — path to the audio
  • Mix % — share of the final blend (0–100%). Replaces the Scale slider when the extension is audio.
  • Timing, fade in / fade out — same as image

Mixing tips

Audio overlays go through amix with the section's native audio. Because amix treats every input as equal voltage (not equal perceived loudness), the inherently-louder source in a mix will dominate. Two overlays at 50% each will NOT come out balanced if one was recorded hotter than the other.

Two levers:

  • Hand-tune Mix % per overlay until the blend sounds right. Typical: quiet background music ends up at 40–60%, ambient beds at 15–25%, and a prominent layer stays at 70–100%.
  • Leave Normalize audio ON in the sidebar (the default). It rebalances levels across sections, so an overlay-heavy section doesn't come out quieter than a section with strong native audio. It does not rebalance inside a single section's mix — that's what Mix % is for.

Text overlays

Form fields:

  • Text — multi-line input. Newlines render as line breaks.
  • Font — dropdown of system fonts (scanned from your OS font directories)
  • Size — in pixels, rendered at output resolution
  • Colour — hex picker
  • Opacity — 0–100%
  • Position — one of the nine slots
  • Timing, fade in / fade out — same as image

Notes:

  • Apostrophes, colons, URLs, and newlines all render as you'd expect. (Under the hood we write the text to a tempfile rather than inlining it, so escaping is not your problem.)
  • Multi-line text positioned on the right (tr / mr / br) is right-aligned; positioned on the left, left-aligned; centred slots, centred.
  • Font availability is per-machine. If you share a project JSON with someone who doesn't have the font, the engine falls back to the first installed system font.

Next: Joiners — controlling the transition between sections.