Video Render — Local (Mac-metal)

Render an ace-web connect-videos program to output.mp4 on the host's Node / Chromium / esbuild (1–3 min) instead of the slower Docker/server /build queue. Wraps ace-web's scripts/render_locally.py. ElevenLabs voiceover + music bed are muxed in; the renderer holds the last frame of a clip range when its narration overruns, so a too-long script shows up as frozen footage (see the timing report below).

When to use

• Iterating on a video locally and you want the fast render, not the server queue.
• Rendering a DDD narrative as a connect-ddd-walkthrough from a spec.yaml + master clip that exist only locally (e.g. canopy's emitter output) — no Drive, no container.
• NOT for publishing to Drive/labs — that's the server /build, or Mode B with --publish.

Prerequisites

• An ace-web checkout (default ~/emdash-projects/ace-web; override $ACE_WEB_ROOT). It vendors the renderer at video-production/connect-videos and scripts/render_locally.py.
• connect-videos deps installed once: cd "$ACE_WEB/video-production/connect-videos" && npm ci (~minutes). The script errors clearly if absent.
• ELEVENLABS_API_KEY in the environment or the ace .env (a value in ACE's Canopy vault on canopy-web). The renderer refuses to silently drop voice.
• ffmpeg on PATH.

Resolve the checkout

ACE_WEB="${ACE_WEB_ROOT:-$HOME/emdash-projects/ace-web}"
[ -f "$ACE_WEB/scripts/render_locally.py" ] || { echo "no ace-web checkout at $ACE_WEB — set ACE_WEB_ROOT"; exit 1; }

Mode A — local spec + master clip (DDD / general, no Drive)

A style: recorded spec does NOT render here. canopy's recorded-walkthrough mode (several standalone cuts, no music, no cards, footage near real time) lives in canopy's own engine; ace-web's vendored copy predates it — its spec.ts has no style field and scripts/render.ts muxes defaults.music_bed unconditionally, so a recorded cut rendered here gets the music bed back (ace#2788). If the narrative's recipe sets style: recorded (each cut is an explainer_spec.<cut>.yaml), render with canopy's video-engine/render_locally.py per /canopy:ddd-recorded-walkthrough instead, and stop reading this mode. Its uploads (snippets upload-video, render_locally.py publish) run through bin/ace-canopy-web --workspace "$WS" -- <command> and are read back with verify walkthrough <id> (playbook/integrations/canopy-web.md, ace#2805).

The caller already has a connect-videos spec.yaml (e.g. canopy's emitted explainer_spec.yaml) and a master clip. Stage + render directly:

cd "$ACE_WEB"
python scripts/render_locally.py \
  --local-spec /path/to/spec.yaml \
  --master     /path/to/walkthrough.mp4 \
  --final            # omit for a faster --draft preview

Slug + run come from the spec (slug: / --run, default run-001); the master is copied to the spec's manifest.master: file:… path. Output: video-production/connect-videos/programs/<slug>/runs/<run>/output.mp4.

Mode B — existing Drive program (Docker app container up)

cd "$ACE_WEB"
python scripts/render_locally.py <program-slug>            # or: <slug> <run-id>
python scripts/render_locally.py --publish <program-slug>  # also push artifacts to Drive

Read the output — the timing report

After rendering the script prints:

clip footage (spec beats):   64.0s
rendered duration:           77.5s
held-frame overrun:         +13.5s  ⚠ VO overruns clips — trim narration

A large overrun means the narration is longer than the footage and the renderer froze the last frame waiting for the VO. Trim the narration to play continuously — budget ≈2.2 words/sec for the ElevenLabs eleven_turbo_v2 voice (not 2.5; that overshoots).

Pointing at a specific renderer

$CONNECT_VIDEOS_ROOT (or --connect-videos-root) overrides just the connect-videos project — render against a canonical install regardless of which checkout the script lives in. Honored by both render_locally.py and its QA probe.

Common mistakes

• Stale checkout — default is ~/emdash-projects/ace-web; set $ACE_WEB_ROOT (or $CONNECT_VIDEOS_ROOT) to target another. Don't render from a feature worktree by accident.
• Missing node_modules — npm ci in connect-videos once; the host arch must match (run on the Mac, not in the Linux container — that's the whole point).
• --publish in local-spec mode — rejected; there's no Drive program. Use Mode B to publish.
• manifest.master not a file: ref — local mode copies --master to the file: path the spec names; emit the spec with a file: master (canopy's DDD emitter does).

Intended caller

canopy's on-demand ddd-ace-render emits the connect-ddd-walkthrough spec + records the master clip, then invokes this skill (Mode A) to produce the narrated MP4.