Subchapter 14.37

Render And Composite

Hershey Script1

Also bundled

39 more in the appendix

scripts/render-and-composite.sh

Raw file

heygen-com/hyperframes

scripts/render-and-composite.sh

Shell469 lines25 KB

1#!/usr/bin/env bash
2# End-to-end: hyperframes render + ffmpeg overlay matte → final.mp4
3#
4# Usage:
5#   bash render-and-composite.sh <project-dir> [hyperframes-repo-path]
6#
7# Env:
8#   HYPERFRAMES_ROOT  override the hyperframes checkout location
9
10set -euo pipefail
11
12PROJECT="${1:?usage: render-and-composite.sh <project-dir

render-and-composite.sh on GitHub

> [hyperframes-repo]

}

"

PROJECT="$(cd "$PROJECT" && pwd)"

# Resolve the hyperframes checkout. Candidate order:

# 1. arg 2 2. $HYPERFRAMES_ROOT 3. repo root if this skill ships INSIDE the

# hyperframes repo (skills/embedded-captions/scripts → ../../..) 4. ~/Downloads/hyperframes

SKILL_SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"

HF=""

for cand in "${2:-}" "${HYPERFRAMES_ROOT:-}" "$(cd "$SKILL_SCRIPT_DIR/../../.." 2>/dev/null && pwd)" "$HOME/Downloads/hyperframes"; do

if [[ -n "$cand" && -f "$cand/packages/cli/dist/cli.js" ]]; then HF="$cand"; break; fi

done

if [[ -z "$HF" ]]; then

echo "[render] hyperframes CLI not found. Set HYPERFRAMES_ROOT to your hyperframes" >&2

echo " checkout (needs packages/cli/dist/cli.js — 'bun install && bun run build')." >&2

exit 1

fi

export HYPERFRAMES_ROOT="$HF" # so the occlusion gate's measure-layout.cjs finds puppeteer too

HF_CLI="$HF/packages/cli/dist/cli.js"

if [[ ! -d "$PROJECT/frames_fg" ]]; then

echo "[render] missing matte frames at $PROJECT/frames_fg — run matte.cjs first" >&2

exit 1

fi

# Which compiler owns this project? Cinematic = make-composition.cjs (plan.json).

# (Standard mode retired 2026-06-12 — rail-surface needs are served by theme

# DNAs like "anchor"; legacy standard.json projects re-render from their

# existing index.html or via the archived compiler in embedded-captions-archive.)

compiler_for() {

echo "make-composition.cjs"

}

if [[ ! -f "$PROJECT/index.html" ]]; then

if [[ -f "$PROJECT/plan.json" ]]; then

C="$(compiler_for)"

echo "[render] no index.html — auto-compiling via $C"

node "$(dirname "$0")/$C" "$PROJECT"

elif [[ -f "$PROJECT/cinematic.json" ]]; then

# cinematic.json-only project: the full compiler lowers blocks → plan.json → html

echo "[render] no index.html — auto-compiling via make-cinematic.cjs"

node "$(dirname "$0")/make-cinematic.cjs" "$PROJECT"

else

echo "[render] missing $PROJECT/index.html and standard.json/plan.json/cinematic.json — author + compile first" >&2

exit 1

fi

elif [[ -f "$PROJECT/cinematic.json" && "$PROJECT/cinematic.json" -nt "$PROJECT/index.html" ]]; then

echo "[render] cinematic.json newer than index.html — recompiling"

node "$(dirname "$0")/make-cinematic.cjs" "$PROJECT"

elif [[ -f "$PROJECT/plan.json" && "$PROJECT/plan.json" -nt "$PROJECT/index.html" ]]; then

C="$(compiler_for)"

echo "[render] plan.json newer than index.html — recompiling via $C"

node "$(dirname "$0")/$C" "$PROJECT"

else

# the COMPILERS themselves may have changed since this project last compiled —

# rendering stale HTML after a compiler fix silently re-ships the old bug

C="$(compiler_for)"

RECOMPILER="$C"

# for cinematic projects the FULL compiler is make-cinematic (compiler_for points

# at make-composition, which only re-emits html from an already-compiled plan)

if [[ -f "$PROJECT/cinematic.json" && "$C" == "make-composition.cjs" ]]; then RECOMPILER="make-cinematic.cjs"; fi

ENGINE="$(dirname "$0")/../modes/cinematic/engine.html"

if [[ "$(dirname "$0")/$RECOMPILER" -nt "$PROJECT/index.html" || "$(dirname "$0")/lib-dna.cjs" -nt "$PROJECT/index.html" || ( -f "$ENGINE" && "$ENGINE" -nt "$PROJECT/index.html" ) ]]; then

echo "[render] compiler/engine newer than index.html — recompiling via $RECOMPILER"

node "$(dirname "$0")/$RECOMPILER" "$PROJECT"

fi

# Embed template fonts BEFORE the gates + render. hyperframes only auto-supplies

# its ~18 canonical fonts; every other template family (Anton, Bangers, VT323,

# Press Start 2P, …) silently falls back to a generic font on a clean/offline/CI

# machine — it only "looks right" locally when that font happens to be installed

# as a system font. inject-fonts inlines the @font-face (base64 woff2, from

# modes/standard/fonts/fonts.css) for whatever non-canonical families each HTML

# actually uses, so measure-layout AND the capture see the true glyph metrics.

# Idempotent; a no-op when every font is canonical/system or already declared.

node "$(dirname "$0")/inject-fonts.cjs" "$PROJECT" \

|| echo "[render] (font embed skipped — inject-fonts.cjs/fonts.css unavailable)" >&2

# gate ledger — each gate appends one line; echoed as a summary before "done"

# (verdicts were drowning hundreds of lines up in ffmpeg logs)

GATES="$PROJECT/_gates.txt"; : > "$GATES"

# Gate: plan.json word timings must align with transcript.json within 80ms.

# A caption whose animation fires 500ms before or after the word is spoken

# breaks the "belongs to the scene" illusion — hard fail, not a warning.

# Skip only if transcript.json is missing (custom mode without transcript).

if [[ -f "$PROJECT/plan.json" && -f "$PROJECT/transcript.json" ]]; then

if ! node "$(dirname "$0")/check-timing.cjs" "$PROJECT" --strict; then

echo "[render] ABORTED — fix plan.json word timings to match transcript.json, then re-run." >&2

exit 2

fi

echo "timing PASS (strict)" >> "$GATES"

fi

# Gate: subject occlusion + frame-edge overflow — pixel-perfect via Chromium DOM

# rects (measure-layout.cjs) × the subject-matte alpha (sharp). Template mode only

# (skipped when plan.json is absent; custom mode uses check-overflow.cjs below).

if [[ -f "$PROJECT/plan.json" && -d "$PROJECT/frames_fg" ]]; then

# check-occlusion prints its verdict, then can intermittently hang on native

# (sharp/libvips) teardown — which would wedge the whole render. Run it under a

# watchdog: once the verdict is printed, a stuck exit can't block us. We read the

# pass/fail from its OUTPUT, not its exit code, so the hang is harmless.

OCC_LOG="$PROJECT/_occlusion.log"

node "$(dirname "$0")/check-occlusion.cjs" "$PROJECT" --strict > "$OCC_LOG" 2>&1 &

OCC_PID=$!; occ_t0=$SECONDS; OCC_RC=""; verdict_at=""

while kill -0 "$OCC_PID" 2>/dev/null; do

# mark when the verdict header is printed (analysis done). if-form: a failed grep

# must NOT trip set -e (it silently killed the whole render on fresh projects).

if [[ -z "$verdict_at" ]] && grep -qE '\[v2\].*word-fail' "$OCC_LOG" 2>/dev/null; then verdict_at=$SECONDS; fi

# verdict printed but still alive 8s later → native (sharp) teardown hang; or no

# verdict after 150s → measure/analysis stuck. Either way: kill + read verdict.

if { [[ -n "$verdict_at" ]] && (( SECONDS - verdict_at > 8 )); } || (( SECONDS - occ_t0 > 150 )); then

kill -9 "$OCC_PID" 2>/dev/null

if grep -q 'cap(s) FAIL' "$OCC_LOG"; then OCC_RC=2; else OCC_RC=0; fi

echo "[render] occlusion gate hung after verdict (sharp teardown) — killed zombie; verdict rc=$OCC_RC" >&2

break

fi

sleep 2

done

if [[ -z "$OCC_RC" ]]; then OCC_RC=0; wait "$OCC_PID" 2>/dev/null || OCC_RC=$?; fi # capture rc without tripping set -e

cat "$OCC_LOG"

if (( OCC_RC != 0 )); then

echo "[render] ABORTED — fix plan.json layout to reduce subject occlusion / frame-edge overflow, then re-run." >&2

echo " Override: OCCLUSION_SKIP=1 bash render-and-composite.sh <project>" >&2

if [[ "${OCCLUSION_SKIP:-0}" != "1" ]]; then

exit 2

fi

echo "[render] OCCLUSION_SKIP=1 set — continuing despite occlusion/overflow warnings." >&2

echo "occlusion+overflow OVERRIDDEN (OCCLUSION_SKIP=1 — conscious accept)" >> "$GATES"

fi

if (( OCC_RC == 0 )); then echo "occlusion+overflow PASS" >> "$GATES"; fi

fi

# Custom mode (no plan.json) skips the template gates above. Run a lightweight,

# mode-agnostic frame-overflow check as a WARNING only — custom designs may bleed

# off-frame intentionally, so it never aborts, but it surfaces captions that fall

# off the canvas (the failure we otherwise only catch by eye).

if [[ ! -f "$PROJECT/plan.json" && -f "$PROJECT/index.html" && -f "$(dirname "$0")/check-overflow.cjs" ]]; then

node "$(dirname "$0")/check-overflow.cjs" "$PROJECT" \

|| echo "[render] (overflow check skipped — Chromium/puppeteer unavailable)" >&2

echo "overflow(index) checked (custom mode, warning-only)" >> "$GATES"

fi

# rail.html gets NO other automated coverage (the occlusion gate only reads plan.json

# caps) — run its overflow check whenever it exists. Was dead code inside the

# no-plan.json branch: Standard always HAS a derived plan.json, so it never ran.

if [[ -f "$PROJECT/rail.html" && -f "$(dirname "$0")/check-overflow.cjs" ]]; then

if node "$(dirname "$0")/check-overflow.cjs" "$PROJECT" rail.html; then

echo "overflow(rail) PASS" >> "$GATES"

else

echo "[render] (rail overflow check skipped — Chromium/puppeteer unavailable)" >&2

echo "overflow(rail) skipped (infra)" >> "$GATES"

fi

# Standard hand-off gate: the PROMOTED climax word must NOT also be revealed in the

# rail during the climax's on-screen window (PIPELINE.md "Rail ↔ climax hand-off").

# Hard-fails on a CONFIRMED duplicate; infra issues (no puppeteer, etc.) exit 0 and

# never block. Override with RAIL_CLIMAX_SKIP=1 for a deliberate exception.

if [[ -f "$PROJECT/rail.html" && -f "$PROJECT/index.html" && -f "$(dirname "$0")/check-rail-climax.cjs" ]]; then

if ! node "$(dirname "$0")/check-rail-climax.cjs" "$PROJECT"; then

echo "[render] ABORTED — the promoted climax word is duplicated in the rail." >&2

echo " Apply the rail↔climax hand-off (PIPELINE.md), then re-run." >&2

echo " Override: RAIL_CLIMAX_SKIP=1 bash render-and-composite.sh <project>" >&2

if [[ "${RAIL_CLIMAX_SKIP:-0}" != "1" ]]; then

exit 2

fi

echo "[render] RAIL_CLIMAX_SKIP=1 — continuing despite the rail/climax duplicate." >&2

echo "rail-climax OVERRIDDEN (RAIL_CLIMAX_SKIP=1)" >> "$GATES"

else

echo "rail-climax PASS (no duplicate reveal)" >> "$GATES"

fi

# FPS: matte.fps (written by matte.cjs at the source's NATIVE rate) is authoritative

# so the matte overlay stays frame-aligned with the render. Falls back to plan.fps /

# frame-count inference / 24. Warn if plan.json fps disagrees with the matte.

FPS=""

if [[ -f "$PROJECT/matte.fps" ]]; then

FPS="$(tr -dc '0-9' < "$PROJECT/matte.fps")"

if [[ -f "$PROJECT/plan.json" ]]; then

PFPS="$(node -e 'try{process.stdout.write(String(require(process.argv[1]).fps??""))}catch(e){}' "$PROJECT/plan.json" 2>/dev/null || true)"

if [[ -n "$PFPS" && "$PFPS" != "$FPS" ]]; then

echo "[render] WARN: plan.json fps=$PFPS != matte fps=$FPS — using matte fps to keep occlusion aligned" >&2

fi

if [[ -z "$FPS" || "$FPS" == "0" ]]; then

if [[ -f "$PROJECT/plan.json" ]]; then

FPS="$(node -e 'process.stdout.write(String(require(process.argv[1]).fps??24))' "$PROJECT/plan.json")"

elif [[ -d "$PROJECT/frames_fg" ]]; then

N="$(ls "$PROJECT/frames_fg" | wc -l | tr -d ' ')"

DUR="$(grep -oE 'data-duration="[0-9.]+"' "$PROJECT/index.html" | head -1 | grep -oE '[0-9.]+' || echo '')"

if [[ -n "$DUR" && "$N" -gt 0 ]]; then

FPS="$(awk "BEGIN{printf \"%d\", $N/$DUR + 0.5}")"

else

FPS=24

fi

else

FPS=24

fi

# Caption layer: "bg" (classic embed — matte overlays subject on top of caps)

# or "fg" (captions always on top — announcement feel, used for 9:16 portraits

# where the subject fills the frame and bg mode loses too much to occlusion).

# Precedence: CLI env flag > plan.json > HTML data attribute > "bg".

CAPTION_LAYER="${CAPTION_LAYER_FLAG:-}"

if [[ -z "$CAPTION_LAYER" && -f "$PROJECT/plan.json" ]]; then

CAPTION_LAYER="$(node -e 'process.stdout.write(String(require(process.argv[1]).caption_layer??"bg"))' "$PROJECT/plan.json")"

fi

if [[ -z "$CAPTION_LAYER" && -f "$PROJECT/index.html" ]]; then

ATTR="$(grep -oE 'data-caption-layer="(bg|fg)"' "$PROJECT/index.html" | head -1 | grep -oE '(bg|fg)' || true)"

if [[ -n "$ATTR" ]]; then CAPTION_LAYER="$ATTR"; fi

fi

CAPTION_LAYER="${CAPTION_LAYER:-bg}"

echo "[render] caption_layer=$CAPTION_LAYER"

BG="$PROJECT/bg_plus_caps.mp4"

FINAL="$PROJECT/final.mp4"

# Snapshot the current index.html + plan.json into history/ so the user

# can recover a prior iteration's design after further edits overwrite it.

HISTORY_DIR="$PROJECT/history"

mkdir -p "$HISTORY_DIR"

STAMP="$(date +%Y%m%d-%H%M%S)"

cp "$PROJECT/index.html" "$HISTORY_DIR/index-${STAMP}.html"

cp "$PROJECT/plan.json" "$HISTORY_DIR/plan-${STAMP}.json" 2>/dev/null || true

echo "[render] snapshot → history/index-${STAMP}.html"

echo "[render] hyperframes render @ ${FPS}fps"

# Hyperframes occasionally hangs on Chromium shutdown *after* the output file

# is successfully written (seen multiple times on 15–30s clips). Without a

# guard the shell waits forever. This helper enforces a max wall-clock budget,

# and if the output is already on disk when we hit it, treats the run as

# successful and kills the zombie. Tune HF_TIMEOUT_S via env if needed.

# Default SCALES with clip size: two parallel Chromium passes on a long clip

# legitimately exceed a fixed 240s (a 38s/1151-frame render was killed at 244s

# while healthy). ~1.5s per source frame, floor 240s.

N_FRAMES="$(ls "$PROJECT/frames_fg" 2>/dev/null | wc -l | tr -d ' ')"

HF_TIMEOUT_S="${HF_TIMEOUT_S:-$(( N_FRAMES * 3 / 2 > 240 ? N_FRAMES * 3 / 2 : 240 ))}"

# hf_render_dir: render one hyperframes composition.

# args: <output.mp4> <label> <project_dir>

# watches for the Chromium-shutdown-hang; if output file exists and is >1MB

# past timeout, treats as success and kills the zombie.

hf_render_dir() {

local out="$1" label="$2" proj="$3" fmt="${4:-}"

# bash 3.2 (macOS) throws on empty-array expansion under `set -u`, so branch

# explicitly instead of splatting an optional --format array.

if [[ -n "$fmt" ]]; then

node "$HF_CLI" render --skill=embedded-captions --dir "$proj" --fps "$FPS" --format "$fmt" --crf 11 -o "$out" &

else

node "$HF_CLI" render --skill=embedded-captions --dir "$proj" --fps "$FPS" --crf 11 -o "$out" &

fi

local pid=$! start=$SECONDS elapsed

while kill -0 "$pid" 2>/dev/null; do

elapsed=$((SECONDS - start))

if (( elapsed > HF_TIMEOUT_S )); then

local sz=0

[[ -f "$out" ]] && sz=$(stat -f%z "$out" 2>/dev/null || echo 0)

if (( sz > 1000000 )); then

echo "[render] ${label}: node hung ${elapsed}s after shutdown (output ${sz}B exists, treating as success)"

kill -9 "$pid" 2>/dev/null

pkill -9 -f "puppeteer_dev_chrome_profile" 2>/dev/null

return 0

fi

echo "[render] ${label}: hung ${elapsed}s with no output — killing and failing" >&2

kill -9 "$pid" 2>/dev/null

pkill -9 -f "puppeteer_dev_chrome_profile" 2>/dev/null

return 2

fi

sleep 5

done

wait "$pid" 2>/dev/null

[[ -f "$out" ]]

}

# Link a project's assets into a shadow render dir EXCEPT the files we manage

# (the HTML we override + render outputs/intermediates). Links every other entry by

# its real name, so the shadow resolves whatever media the HTML references — including

# the ORIGINAL video filename `hyperframes init` scaffolds (e.g. clip.mp4), not just a

# fixed allow-list. Prevents the shadow-render 404 → silent/frozen output → abort.

link_assets() { # <project> <shadow>

local proj="$1" sh="$2" b

for p in "$proj"/*; do

[[ -e "$p" ]] || continue

b="$(basename "$p")"

case "$b" in

esac

ln -sf "$p" "$sh/$b"

done

}

# Hybrid renders need 2 independent hyperframes passes. They share no state, so

# we run them in parallel (one in the main PROJECT, one in a shadow dir with

# index_fg.html renamed to index.html). Saves ~half of the Chromium cost.

FG_SHADOW=""

if [[ -f "$PROJECT/index_fg.html" ]]; then

FG_SHADOW="$PROJECT/_fg_shadow"

rm -rf "$FG_SHADOW" && mkdir -p "$FG_SHADOW"

# Link shared assets (any media filename); copy index_fg.html into shadow as index.html.

link_assets "$PROJECT" "$FG_SHADOW"

cp "$PROJECT/index_fg.html" "$FG_SHADOW/index.html"

FG_CAPS="$PROJECT/fg_caps.mp4"

echo "[render] hybrid fg/bg — launching both passes in parallel"

hf_render_dir "$BG" "bg_plus_caps" "$PROJECT" &

BG_PID=$!

hf_render_dir "$FG_CAPS" "fg_caps" "$FG_SHADOW" &

FG_PID=$!

# Wait for both; fail if either fails.

BG_RC=0; wait "$BG_PID" || BG_RC=$?

FG_RC=0; wait "$FG_PID" || FG_RC=$?

rm -rf "$FG_SHADOW"

if (( BG_RC != 0 )); then echo "[render] bg render failed" >&2; exit 1; fi

if (( FG_RC != 0 )); then echo "[render] fg render failed" >&2; exit 1; fi

elif [[ -f "$PROJECT/rail.html" ]]; then

# Standard mode: TWO independent hyperframes passes (base = index.html with the

# embed; rail = rail.html transparent). Each renders from its own shadow dir (the

# multiple-root ambiguity), and they share no state — run them IN PARALLEL like

# the fg-hybrid above (~halves the Chromium wall time). The rail webm is consumed

# by the composite stage below, which finds it already rendered.

BASE_SHADOW="$PROJECT/_base_shadow"; rm -rf "$BASE_SHADOW"; mkdir -p "$BASE_SHADOW"

link_assets "$PROJECT" "$BASE_SHADOW"

cp "$PROJECT/index.html" "$BASE_SHADOW/index.html"

RAIL_SHADOW="$PROJECT/_rail_shadow"; rm -rf "$RAIL_SHADOW"; mkdir -p "$RAIL_SHADOW"

link_assets "$PROJECT" "$RAIL_SHADOW"

cp "$PROJECT/rail.html" "$RAIL_SHADOW/index.html"

RAIL_WEBM="$PROJECT/rail.webm"

echo "[render] standard base + rail — launching both passes in parallel"

hf_render_dir "$BG" "bg_plus_caps" "$BASE_SHADOW" &

BASE_PID=$!

hf_render_dir "$RAIL_WEBM" "rail" "$RAIL_SHADOW" "webm" &

RAIL_PID=$!

BASE_RC=0; wait "$BASE_PID" || BASE_RC=$?

RAIL_RC=0; wait "$RAIL_PID" || RAIL_RC=$?

rm -rf "$BASE_SHADOW" "$RAIL_SHADOW"

if (( BASE_RC != 0 )); then echo "[render] bg render failed" >&2; exit 1; fi

if (( RAIL_RC != 0 )); then echo "[render] rail render failed" >&2; exit 1; fi

else

hf_render_dir "$BG" "bg_plus_caps" "$PROJECT" \

|| { echo "[render] bg render failed" >&2; exit 1; }

fi

# Probe render dims for ffmpeg scale

W="$(ffprobe -v error -select_streams v:0 -show_entries stream=width -of default=nw=1:nk=1 -- "$BG")"

H="$(ffprobe -v error -select_streams v:0 -show_entries stream=height -of default=nw=1:nk=1 -- "$BG")"

# Clamp every composite to the matte (= source-video) length. The render uses

# plan.duration / data-duration, which can exceed the source (e.g. Whisper word

# timestamps overrun the clip). Past the source the a-roll is gone (black) but the

# matte overlay repeats its last frame → the tail shows the subject floating on

# black. frames_fg count/fps APPROXIMATES the source length, but fractional-rate

# sources (29.97) get over-extracted by integer-fps rounding (e.g. 544 frames for

# a 542-frame 18.085s clip -> 544/30 = 18.133s -> ~1.5 trailing BLACK frames after

# the a-roll stream ends). The true a-roll duration is authoritative: clamp to

# min(matte frames / fps, source duration).

MATTE_DUR="$(awk "BEGIN{printf \"%.3f\", $(ls "$PROJECT/frames_fg" | wc -l)/$FPS}")"

SRC_DUR="$(ffprobe -v error -show_entries format=duration -of csv=p=0 -- "$PROJECT/source.mp4" 2>/dev/null || true)"

if [[ -n "${SRC_DUR:-}" ]]; then

MATTE_DUR="$(awk "BEGIN{m=$MATTE_DUR; s=$SRC_DUR; printf \"%.3f\", (s>0 && s<m) ? s : m}")"

fi

echo "[render] clamp output to source/matte length: ${MATTE_DUR}s"

# Bug-1 guard: the background plate ($BG) must be at least the matte/source length,

# else the tail (where the bg ran out but the matte continues) shows ONLY the

# foreground subject on black. Cinematic auto-fixes this (make-composition sets the

# canvas = source length); this catches a hand-authored Standard duration set to the

# last-caption time instead of the clip length. Clamp to the bg length so we never

# ship the only-foreground tail, and tell the author the real fix.

if [[ -f "$BG" ]]; then

BG_DUR="$(ffprobe -v error -show_entries format=duration -of default=nokey=1:noprint_wrappers=1 -- "$BG" 2>/dev/null | tr -dc '0-9.')"

if [[ -n "$BG_DUR" ]] && awk "BEGIN{exit !($BG_DUR < $MATTE_DUR - 0.3)}"; then

echo "[render] ⚠ background plate is ${BG_DUR}s but the clip is ${MATTE_DUR}s — the composition is shorter than the footage." >&2

echo " The tail would show ONLY the foreground subject on black. FIX: set the composition" >&2

echo " duration to the SOURCE clip length (data-duration on #root/#a-roll); captions may still" >&2

echo " end earlier. Clamping output to ${BG_DUR}s for now to avoid the broken tail." >&2

MATTE_DUR="$BG_DUR"

fi

# ─────────────────────────────────────────────────────────────────────────────

# STANDARD mode (rail + embed) — detected by rail.html.

# $BG = index.html rendered (source video + the embed climax).

# (1) overlay the subject matte so the subject occludes the climax (embed = behind).

# (2) render rail.html → transparent WebM (the verbatim rail).

# (3) alpha-composite the rail IN FRONT so it is never occluded (rail = on top).

# The existing Cinematic paths below are untouched.

if [[ -f "$PROJECT/rail.html" ]]; then

MATTED="$PROJECT/_matted.mp4"

if [[ "$CAPTION_LAYER" == "fg" ]]; then

# caption_layer:fg — the climax sits IN FRONT of the subject (no behind-subject

# embed possible, e.g. a frame-filling 9:16 subject). bg_plus_caps already has the

# climax drawn over the video, so we SKIP the matte overlay (which would push the

# subject back in front of it). The rail still overlays on top below.

echo "[render] STANDARD (rail + FRONT climax) — caption_layer=fg, matte overlay skipped (${W}x${H})"

cp "$BG" "$MATTED"

else

echo "[render] STANDARD (rail + embed) — embed behind subject, rail alpha-overlaid in front (${W}x${H})"

ffmpeg -y -i "$BG" \

-framerate "$FPS" -i "$PROJECT/frames_fg/f_%04d.png" \

-filter_complex "[1:v]scale=${W}:${H},format=yuva420p[m];[0:v][m]overlay=format=auto[v]" \

-map "[v]" -map 0:a -r "$FPS" -t "$MATTE_DUR" -c:v libx264 -crf 11 -preset medium -c:a copy "$MATTED"

fi

# rail.webm was already rendered IN PARALLEL with the base pass above.

RAIL_WEBM="$PROJECT/rail.webm"

[[ -f "$RAIL_WEBM" ]] || { echo "[render] rail.webm missing (parallel rail pass failed?)" >&2; exit 1; }

# alpha-overlay the transparent rail in front of the matted video (force vp9

# decode so the WebM alpha plane is honoured by overlay)

ffmpeg -y -i "$MATTED" -c:v libvpx-vp9 -i "$RAIL_WEBM" \

-filter_complex "[0:v][1:v]overlay=format=auto[v]" \

-map "[v]" -map 0:a -r "$FPS" -t "$MATTE_DUR" -c:v libx264 -crf 11 -preset medium -c:a copy "$FINAL"

rm -f "$MATTED"

if [[ -s "$GATES" ]]; then echo "[render] ── gates ──"; sed 's/^/[render] /' "$GATES"; fi

echo "[render] done → $FINAL"

exit 0

fi

# Decide composite mode:

# - If make-composition emitted index_fg.html (any group has layer:fg),

# use hybrid regardless of plan-level caption_layer.

# - Else if caption_layer=fg globally, skip matte.

# - Else (default), matte embed.

if [[ -f "$PROJECT/index_fg.html" ]]; then

# Hybrid: bg_plus_caps and fg_caps were both rendered above in parallel.

# Now composite: bg_plus_caps + matte (subject on top) + fg_caps (screen).

FG_CAPS="$PROJECT/fg_caps.mp4"

echo "[render] hybrid — composite (bg_plus_caps + matte + fg_caps[screen blend])"

# fg_caps is bright caption on pure black. blend=screen makes it behave

# like CSS mix-blend-mode: screen on the matted video — captions pick up

# scene luminance, NOT a flat opaque overlay (which looks sticker-like).

# Use rgb format to avoid YUV-space color drift, then convert back for libx264.

ffmpeg -y -i "$BG" \

-framerate "$FPS" -i "$PROJECT/frames_fg/f_%04d.png" \

-i "$FG_CAPS" \

-filter_complex "[1:v]scale=${W}:${H},format=yuva420p[matte];[0:v][matte]overlay=format=auto,format=gbrp[matted];[2:v]format=gbrp[fg];[matted][fg]blend=all_mode=screen,format=yuv420p[v]" \

-map "[v]" -map 0:a \

-r "$FPS" -t "$MATTE_DUR" -c:v libx264 -crf 12 -preset medium -c:a copy \

"$FINAL"

elif [[ "$CAPTION_LAYER" == "fg" ]]; then

# Global FG mode: skip matte overlay entirely. bg_plus_caps.mp4 already

# has captions on top of a-roll. Re-encode for consistency.

echo "[render] fg mode (global) — skipping matte, re-encoding ${W}x${H}"

ffmpeg -y -i "$BG" \

-r "$FPS" -t "$MATTE_DUR" -c:v libx264 -crf 12 -preset medium -c:a copy \

"$FINAL"

else

echo "[render] bg mode — overlay matte (${W}x${H})"

ffmpeg -y -i "$BG" \

-framerate "$FPS" -i "$PROJECT/frames_fg/f_%04d.png" \

-filter_complex "[1:v]scale=${W}:${H},format=yuva420p[fg];[0:v][fg]overlay=format=auto[v]" \

-map "[v]" -map 0:a \

-r "$FPS" -t "$MATTE_DUR" -c:v libx264 -crf 12 -preset medium -c:a copy \

"$FINAL"

fi

if [[ -s "$GATES" ]]; then echo "[render] ── gates ──"; sed 's/^/[render] /' "$GATES"; fi

echo "[render] done → $FINAL"