What is audio-sync-assembly?

A workflow for turning rendered video scenes and narration into one precisely timed video using FFmpeg, a command-line media tool. It covers checking media properties, adjusting scene timing, handling pauses, and aligning visuals with spoken phrases.

Use it when assembling scenes, retiming clips, adding pauses, joining video, or matching visual events to narration.

It prevents narration, scene changes, and product moments from falling out of sync.

audio-sync-assembly — Skill for Claude Code and Codex by saranambiar

Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

Any agent

npx skills add saranambiar/hyperframes-video-agent-skills --skill audio-sync-assembly

Clone the repo

git clone --depth 1 https://github.com/saranambiar/hyperframes-video-agent-skills

Made for: Claude Code, Codex.

Wrote this? Show the measurements

A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.

README.md

[![agentmods](https://agentmods.dev/badge/skills/saranambiar/hyperframes-video-agent-skills/audio-sync-assembly/github.svg)](https://agentmods.dev/skills/saranambiar/hyperframes-video-agent-skills/audio-sync-assembly)

Your own site

<a href="https://agentmods.dev/skills/saranambiar/hyperframes-video-agent-skills/audio-sync-assembly"><img src="https://agentmods.dev/badge/skills/saranambiar/hyperframes-video-agent-skills/audio-sync-assembly/github.svg" alt="Measured on agentmods" height="20"></a>

Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.

Your own site · 80×15

<a href="https://agentmods.dev/skills/saranambiar/hyperframes-video-agent-skills/audio-sync-assembly"><img src="https://agentmods.dev/badge/skills/saranambiar/hyperframes-video-agent-skills/audio-sync-assembly.svg" alt="Reviewed on agentmods" width="80" height="20"></a>

Per session 69 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.

When invoked 863 The whole file, excluding the scripts and references it only reads on demand.

Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe.

Origin original No closer match found in the catalogue.

Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

Model	Per session	Once invoked
Fable 5.1	$0.00069	$0.00863
Opus 5.5	$0.00028	$0.00345
Sonnet 5.5	$0.00014	$0.00173
Haiku 4.5	$0.00007	$0.00086

Measured 2mo ago against content hash b56ae9696009, method: parsed. Prices are Anthropic first-party input rates as of 2026-10-07, from the pricing page.

Security

Grade A, and why

audio-sync-assembly scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 2mo ago.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

skills/audio-sync-assembly/SKILL.md · 161 lines

How it starts

The opening of the file, as written. The whole thing — 161 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Audio Sync Assembly

Use this skill when video timing must follow narration or when multiple rendered scenes need to become one final timeline.

Source Of Truth

Use the latest approved narration audio as timing source.
Use scene renders as visual source.
Use templates/timeline-manifest.example.json to record target timing.
Do not infer timings from old final MP4s if source renders and audio clips exist.

Probe First

For every clip:

Duration.
Frame rate.
Resolution.
Audio stream presence.
Sample rate and channels.

Use ffprobe or this repo's media probe script once available.

Sync Strategy

Choose the smallest timing intervention:

Simple scene: retime whole scene to narration length with setpts.
Scene with cue points: split into segments and retime each segment.
Narration pause: insert silence and hold a frame.
Replacement audio slightly longer: use small audio-only atempo only if preserving downstream sync matters more than raw duration.
Product moment late/early: retime the segment before the product moment.

Read references/ffmpeg-retiming.md for command patterns.

Phrase Alignment

Map spoken phrase starts to global timestamps when visuals depend on narration:

Question cards.
Product states.
Chart points.
Scene title reveals.
CTA/logo arrival.

Caption timing and visual timing should share the same narration timeline.

Assembly Order

Build synced scene segments.
Concatenate synced segments into a narration-only master.
Generate captions from narration-only master.
Burn captions.
Build music bed.
Mix narration and ducked music.
Produce final MP4 and preview clips.

QA

Probe final duration, frame rate, resolution, and audio.
Watch boundary previews.
Check exact cue timestamps with proof frames.
Listen for clipped words after trims.
Confirm no accidental blank final frame appears.

Output

Return:

Timeline manifest or script updates.
Final path.
Scene start map.
Preview clips.
Proof frames and probe results.

Read the full file on GitHub · 161 lines

Files

What ships with it

1 file beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.

references/ffmpeg-retiming.md 1.1 KB

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

2mo ago First seen · 161 lines · 69 tokens per session scan A b56ae9696009

Subscribe to this mod's changes

audio-sync-assembly is a skill published in the GitHub repository saranambiar/hyperframes-video-agent-skills (47 stars, last pushed 4mo ago), licensed Apache-2.0. It adds 69 tokens to every session and 863 once invoked, about $0.0003 per session on Opus 5.5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.

Creative and media

audio-sync-assembly next to 6 skills from other repositories
Mod	Type	Stars	Last push	Licence	Scan	Tokens	Works with
audio-sync-assemblysaranambiar/hyperframes-video-agent-skills	Skill	47	4mo ago	Apache-2.0	A	69	Claude Code, Codex
imagegenopenai/codex	Skill	133k	yesterday	Apache-2.0	A	113	Codex
playwright-climicrosoft/playwright	Skill	99k	yesterday	Apache-2.0	A	19	Claude Code
local-ai-agentsmicrosoft/ai-agents-for-beginners	Skill	79k	4d ago	MIT	A	200	Claude Code, Codex
systematic-debuggingobra/superpowers	Skill	313k	3d ago	MIT	A	21	Claude Code
next-cache-components-adoptionvercel/next.js	Skill	143k	yesterday	MIT	A	95	Claude Code
next-partial-prefetching-adoptionvercel/next.js	Skill	143k	yesterday	MIT	A	103	Claude Code