Agent-Skills.md

Agent Skills: Viral Video Platform Specifications

Complete platform upload specifications for viral video creation across TikTok, YouTube Shorts, Instagram Reels, Facebook Reels, Snapchat Spotlight, and Twitter/X. PROACTIVELY activate for: (1) Platform-specific video encoding, (2) Upload requirements lookup, (3) Multi-platform export, (4) File size optimization, (5) Aspect ratio conversion, (6) Duration limits, (7) Audio requirements, (8) Caption/subtitle specs, (9) Thumbnail requirements, (10) Quality vs compatibility trade-offs. Provides: Comprehensive spec tables, FFmpeg presets per platform, optimal encoding settings, file size calculators, batch export workflows, and 2025-2026 platform-specific algorithm insights.

UncategorizedID: josiahsiegel/claude-plugin-marketplace/viral-video-platform-specs

Repository

josiahsiegel/claude-plugin-marketplace
JosiahSiegelLicense: MIT
213

Install this agent skill to your local

pnpm dlx add-skill https://github.com/JosiahSiegel/claude-plugin-marketplace/tree/HEAD/plugins/ffmpeg-social-video/skills/viral-video-platform-specs

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plugins/ffmpeg-social-video/skills/viral-video-platform-specs/SKILL.md

Skill Metadata

Name
viral-video-platform-specs
Description
|

Viral Video Platform Specifications

Use this skill to choose export settings for TikTok, YouTube Shorts, Instagram Reels, Facebook Reels, Snapchat Spotlight, Twitter/X, Pinterest, LinkedIn, and mobile-browser playback. This SKILL is a lean orchestrator; detailed platform tables, commands, and recipes are preserved in references/platform-details-and-recipes.md.

Quick Reference

| Platform | Aspect | Recommended resolution | Practical duration | Max size | Default codec | |---|---:|---:|---:|---:|---| | TikTok | 9:16 | 1080x1920 | 21-34s | 287 MB iOS | H.264 + AAC | | YouTube Shorts | 9:16 | 1080x1920 | 50-59s | 256 GB | H.264 or VP9 | | Instagram Reels | 9:16 | 1080x1920 | 7-30s | 4 GB | H.264 + AAC | | Facebook Reels | 9:16 | 1080x1920 | 15-30s | 4 GB | H.264 + AAC | | Snapchat Spotlight | 9:16 | 1080x1920 | <=60s | 300 MB | H.264 + AAC | | Twitter/X | 9:16, 16:9, 1:1 | 1080x1920 | <=140s | 512 MB | H.264 + AAC |

Universal Social Export Baseline

ffmpeg -i input.mp4 \
  -vf "scale=1080:1920:force_original_aspect_ratio=decrease,pad=1080:1920:(ow-iw)/2:(oh-ih)/2:black,setsar=1,fps=30" \
  -c:v libx264 -preset medium -crf 22 -profile:v high -level 4.1 \
  -c:a aac -b:a 192k -ar 48000 -ac 2 \
  -pix_fmt yuv420p -movflags +faststart \
  output_social.mp4

Adjust loudness, duration, bitrate, and metadata per platform from the reference file.

Core Workflow

  1. Verify ffmpeg -version; prefer current stable builds for security and codec fixes.
  2. Identify target platform(s) and whether the video is native-app upload or mobile-browser playback.
  3. Normalize to vertical 9:16 unless the platform or campaign calls for square/horizontal.
  4. Use H.264/AAC for the broadest acceptance. Use VP9 only when intentionally targeting YouTube/WebM.
  5. Apply platform loudness targets: TikTok/Reels often around -10 to -12 LUFS; YouTube around -14 LUFS; Facebook around -13 LUFS.
  6. Keep -pix_fmt yuv420p and -movflags +faststart for compatibility.
  7. Verify output with ffprobe before upload.

Key Gotchas

  • All major social platforms re-encode uploads; high-quality H.264 is usually a better upload source than HEVC/AV1 for social delivery.
  • For web/mobile-browser playback, profile/level, yuv420p, and faststart matter more than platform upload limits.
  • Keep captions and UI out of unsafe top/bottom regions, especially lower 35% on Reels-style interfaces.
  • Two-pass bitrate control is useful when a platform file-size ceiling is strict.

Reference Map

  • references/platform-details-and-recipes.md - Full preserved reference: per-platform spec tables, FFmpeg presets, two-pass examples, multi-platform export script, file-size calculation, codec comparison, mobile-safe playback, color grading, text/caption readability, verification commands, sources.

Related Skills

  • viral-video-animated-captions - CapCut-style caption generation
  • viral-video-hook-templates - Hook patterns and retention tactics
  • ffmpeg-animation-timing-reference - Timing, readability, sync, and platform pacing
  • ffmpeg-command-syntax - Correct option placement
Viral Video Platform Specifications Skill | Agent Skills