القائمة
ffmpeg patterns for video pipelines — filters, audio, concat, GIF generation, codec settings. Covers Ken Burns, letterbox, fade, multi-act assembly, and macOS gotchas.
التثبيت باستخدام Codex أو Claude انسخ هذا Prompt والصقه في Codex أو Claude أو مساعد آخر ليراجع صفحة Skill ويثبّتها لك.
استنادا إلى تصنيف SOC المهني
Python CLI patterns — typer apps, uv with PEP 723 inline deps, pytest, pathlib, atomic file writes, file locking, JSONL streaming, and production-grade stdlib idioms for command-line tools
Commanded CQRS/event-sourcing patterns for aggregates, commands, events, process managers, projections, and event handlers
Phoenix LiveView patterns for stateful server-rendered UI including streams, async assigns, components, forms, uploads, and JS hooks
Oban background job patterns — workers, queues, scheduling, unique jobs, retries, telemetry, engines, and Oban Pro features (Workflow, Batch)
Elixir testing patterns — ExUnit organization, ExMachina factories, Mox boundary mocking, Bypass HTTP stubbing, parameterize, sandbox patterns, and async-safe concurrency
Ecto database patterns — schemas, changesets, query composition, Multi transactions, migrations, ParameterizedType, UUIDv7, and performance tuning
| name | ffmpeg-expert |
| description | ffmpeg patterns for video pipelines — filters, audio, concat, GIF generation, codec settings. Covers Ken Burns, letterbox, fade, multi-act assembly, and macOS gotchas. |
inputs (-i) → [filter graph: -vf / -af / -filter_complex] → codec flags → output
, — applied in order; and [labels] — for complex graphs (split, overlay, amix)-an strips audio output; -vn strips video output-map 0:v:0 -map 1:a:0 — explicit stream selection when merging inputs| I need to... | Use |
|---|---|
| Photo → video with Ken Burns zoom | → references/filters.md |
| Letterbox any source to 1920×1080 | → references/filters.md |
| Fade video in/out | → references/filters.md |
| Normalize fps + SAR before concat | → references/filters.md |
| Loop a short song over a longer video | → references/audio.md |
| Fade audio in/out | → references/audio.md |
| Merge separate video + audio files | → references/audio.md |
| Fix silent audio after concat | → references/audio.md (sample rate) |
| Join pre-built segments | → references/pipeline-patterns.md |
| Multi-act pipeline with per-act music | → references/pipeline-patterns.md |
| Extract a frame from video | → references/pipeline-patterns.md |
| Create a quality GIF | → references/gif.md |
| Boomerang / speed-ramped GIF | → references/gif.md |
| Issue | Fix |
|---|---|
bc aliased | Use /usr/bin/bc explicitly |
BSD date rejects GNU flags | date -j -f '%Y-%m-%d' "YYYY-MM-DD" '+%B %Y' |
| HEIC not recognized | brew install libheif |
| Glob matches nothing → literal string passed | shopt -s nullglob at script top |
fade=t=out:st= uses scientific notation | printf '%.6f' $(echo "$d - $f" | /usr/bin/bc) |
| Audio silent after concat | Mismatched sample rates — add -ar 48000 to all audio prep |
| DTS errors in concat | Mixed fps or SAR — normalize before joining |
ffmpeg 8: -framerate on concat removed | Use duration directive in list file instead |
| Zoompan pixelates at zoom | Render at 2× resolution, downscale after (see filters.md) |
-c:v libx264 -crf 18 -preset slow -pix_fmt yuv420p # archival quality
-c:v libx264 -crf 26 -preset medium # shareable / preview
-c:a aac -b:a 192k -ar 48000 # audio (always set -ar)
-movflags +faststart # web streaming
CRF scale: 0 = lossless, 18 = high quality, 23 = default, 28 = small file, 51 = worst.
ffprobe -v quiet -show_entries format=duration -of csv=p=0 "$file"
# returns float seconds, e.g. 12.345678
references/filters.md — Ken Burns/zoompan, letterbox, fade, fps/SAR normalization, drawtextreferences/audio.md — stream_loop, afade, sample rate, audio merge patternsreferences/pipeline-patterns.md — concat demuxer, photo→video, multi-act assemblyreferences/gif.md — two-pass palette, boomerang, speed, size optimization