Showcase Video Builder

Build polished showcase and demo videos from screenshots, avatars, and text overlays using ffmpeg. Use when creating demo reels, hackathon presentations, pro...

Security Scan

The skill is internally consistent: it documents and uses ffmpeg locally to build videos from images, asks for no secrets, and contains only a simple helper script that operates on a user-specified images directory.

Purpose & Capability

Name/description match the implementation: SKILL.md and scripts instruct only local ffmpeg usage to turn screenshots into videos. Required binary (ffmpeg) is appropriate and sufficient for the stated purpose.

Instruction Scope

Instructions and the included script operate on local files (images) and local ffmpeg invocations. They do not attempt to read unrelated system config, environment secrets, or contact external endpoints. The script processes all PNGs in the provided directory, which is expected behavior for a slideshow builder.

Install Mechanism

No install spec — instruction-only with a shell script. Nothing is downloaded or written to system locations by the skill itself; the only runtime requirement is an existing ffmpeg binary.

Credentials

The skill declares no required environment variables or credentials. The script allows overriding the ffmpeg command via the FFMPEG env var (reasonable and limited). No secrets or unrelated service tokens are requested.

Persistence & Privilege

always is false and the skill does not request persistent presence or modify other skills or system-wide agent settings. It runs on demand and performs local, limited operations.

Assessment

This skill appears safe and does what it says: run ffmpeg locally to build videos from images. Before running: ensure ffmpeg is installed from a trusted source, verify the images directory you pass to the script (it will process all PNGs there), and adjust the font path if you're not on macOS. The script honors FFMPEG env override if you need to point to a specific binary. If you allow an automated agent to invoke this skill, remember it will run ffmpeg commands on whatever image directory you (or the agent) provide — avoid passing sensitive system paths. If you need network/media uploads, handle those steps separately; this skill performs no network calls or credential handling.

Turn screenshots and images into polished demo videos with Ken Burns pan/zoom effects, crossfade transitions, and text overlays. Built for hackathon teams and OSS projects that need showcase content without video editing software.

Core Patterns

Image Slideshow with Crossfades

ffmpeg -loop 1 -t 4 -i slide1.png \
       -loop 1 -t 4 -i slide2.png \
       -loop 1 -t 4 -i slide3.png \
       -filter_complex \
       "[0:v]scale=1920:1080:force_original_aspect_ratio=decrease,pad=1920:1080:(ow-iw)/2:(oh-ih)/2,setsar=1,fade=t=out:st=3:d=1[v0]; \
        [1:v]scale=1920:1080:force_original_aspect_ratio=decrease,pad=1920:1080:(ow-iw)/2:(oh-ih)/2,setsar=1,fade=t=in:st=0:d=1,fade=t=out:st=3:d=1[v1]; \
        [2:v]scale=1920:1080:force_original_aspect_ratio=decrease,pad=1920:1080:(ow-iw)/2:(oh-ih)/2,setsar=1,fade=t=in:st=0:d=1[v2]; \
        [v0][v1][v2]concat=n=3:v=1:a=0[out]" \
       -map "[out]" -c:v libx264 -pix_fmt yuv420p output.mp4

Ken Burns (Slow Zoom)

# Slow zoom in over 5 seconds
ffmpeg -loop 1 -t 5 -i image.png -filter_complex \
  "scale=8000:-1,zoompan=z='min(zoom+0.0015,1.5)':x='iw/2-(iw/zoom/2)':y='ih/2-(ih/zoom/2)':d=150:s=1920x1080:fps=30" \
  -c:v libx264 -pix_fmt yuv420p -t 5 zoomed.mp4

Text Overlay

# macOS: use /System/Library/Fonts/Helvetica.ttc
ffmpeg -i input.mp4 -vf \
  "drawtext=text='Built in 48 Hours':fontfile=/System/Library/Fonts/Helvetica.ttc:fontsize=48:fontcolor=white:x=(w-text_w)/2:y=h-80:enable='between(t,2,5)'" \
  -c:v libx264 -c:a copy output.mp4

Title Card (Solid Colour + Text)

ffmpeg -f lavfi -i "color=c=0x6366F1:s=1920x1080:d=3" -vf \
  "drawtext=text='Your Project Name':fontfile=/System/Library/Fonts/Helvetica.ttc:fontsize=72:fontcolor=white:x=(w-text_w)/2:y=(h-text_h)/2" \
  -c:v libx264 -pix_fmt yuv420p title.mp4

Concatenate Segments

# Create concat list
echo "file 'title.mp4'" > concat.txt
echo "file 'slides.mp4'" >> concat.txt
echo "file 'closing.mp4'" >> concat.txt

ffmpeg -f concat -safe 0 -i concat.txt -c copy final.mp4

Platform Tips

• LinkedIn: Autoplays muted — don't rely on audio. Use text overlays for key messages.
• Twitter/X: 2:20 max (free tier). 280 char caption limit. Media upload needs OAuth 1.0a.
• Resize for embedding: Avatars 150px, screenshots 600px, composites 700px. Keeps file under 5MB.

Lessons

• macOS font path: /System/Library/Fonts/Helvetica.ttc — if drawtext fails, check this first
• Always use -pix_fmt yuv420p — without it, some players show a green screen
• Ken Burns on large images is slow — pre-scale to 2x target resolution, not 8x

Files

• scripts/build_showcase.sh — Complete showcase builder script with configurable sections