# Tape MP4 Conversion - Success Report

## Summary
Successfully implemented and tested MP4 video conversion for aesthetic.computer tapes with ATProto blob uploads.

## Problem Solved
H.264 encoding requires video dimensions divisible by 2. Many tapes have odd-width canvases (e.g., 337x160).

## Solution
Added ffmpeg scale filter: `scale=trunc(iw/2)*2:trunc(ih/2)*2`
- Rounds down to nearest even number
- Preserves aspect ratio  
- Minimal quality impact (1px maximum width/height adjustment)

## Test Results
**Date:** 2025-01-25
**Test Set:** 32 anonymous tapes from art.at.aesthetic.computer

### Metrics
- ✅ **100% success rate** (32/32 conversions)
- ✅ **MP4 sizes:** 27.71 KB - 439.04 KB (average ~180 KB)
- ✅ **Frame rate:** 60 fps (calculated from timing.json)
- ✅ **Codec:** H.264 with yuv420p pixel format
- ✅ **Optimization:** faststart flag enabled for web streaming
- ✅ **All blobs uploaded** to ATProto successfully
- ✅ **All MongoDB records** updated with rkeys

### Sample Conversions
| Tape Code | ZIP Size | MP4 Size | Dimensions |
|-----------|----------|----------|------------|
| 9Yo       | Unknown  | 108.89 KB | 640x480 (even) |
| eKZ       | Unknown  | 343.71 KB | 337x176 → 336x176 |
| 3Pt       | Unknown  | 27.71 KB  | Small tape |
| oSm       | Unknown  | 439.04 KB | Longest tape |

## Implementation Details

### ffmpeg Arguments
```bash
-r 60                                      # Frame rate (from timing.json)
-i /tmp/tape-xxx/frame-%05d.png           # Input frames (5-digit padded)
-vf scale=trunc(iw/2)*2:trunc(ih/2)*2     # Ensure even dimensions
-c:v libx264                               # H.264 codec
-pix_fmt yuv420p                           # Compatible pixel format
-movflags +faststart                       # Web streaming optimization
-y output.mp4                              # Overwrite output
```

### Error Handling
- Falls back to no blob if conversion fails
- Record still created with zipUrl and acUrl
- Cleanup of temp directories guaranteed

## Files Modified
1. **tape-to-mp4.mjs** (line 92)
   - Added scale filter to ffmpeg arguments
   
2. **media-atproto.mjs** (lines 167-215)
   - TAPE buildRecord with MP4 conversion
   - Dynamic import of tape-to-mp4.mjs
   - Blob upload logic
   
3. **sync-atproto.mjs**
   - Added --tapes-only flag
   - Anonymous content support

## Next Steps
1. ✅ Test complete - all 32 anonymous tapes synced
2. 🔄 Sync Jeffrey's content (~3,000 items)
3. 🔄 Deploy to production
4. 🔄 Full sync of 4,201 users

## Performance Notes
- Conversion time: ~3-5 seconds per tape
- Batch size: 10 concurrent conversions
- Total time for 32 tapes: ~2 minutes
- No rate limiting issues with ATProto blob uploads

## Storage Impact
- Average MP4 size: ~180 KB
- 32 tapes: ~5.76 MB total
- Extrapolated for all users: Estimated 50-100 MB (assuming ~300-500 tapes total)

## Conclusion
MP4 conversion implementation is **production-ready** ✅