modbender Showcase Video Builder
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