VariaReEncoder

Batch transcoder for Garmin Varia dashcam footage. Converts H.264 source clips to HEVC MP4, optimized for Apple Photos / QuickTime compatibility, with sidecar JSON copy and a telemetry manifest placeholder for a future FIT sync pipeline.

Requirements

macOS or Linux
ffmpeg and ffprobe in PATH (any recent version with libx265/libx264; videotoolbox on macOS)
Bash 3.2+

Quick Start

# Transcode everything in SampleFootage → Output (hardware encoder on macOS)
./garmin_varia_transcode.sh -s SampleFootage -d Output

# Preview what would happen without writing any files
./garmin_varia_transcode.sh -s SampleFootage -d Output --dry-run

# Single file, verbose output
./garmin_varia_transcode.sh -s SampleFootage/Day/clip.mp4 -d Output --verbose

# Transcode + delete originals after validation
./garmin_varia_transcode.sh -s SampleFootage -d Output --move-source

Encoding Modes

Mode	Encoder	Speed (30s clip)	Power*	Use when
`hardware`	hevc_videotoolbox	~4-5s	~35W	Default — battery, large libraries, dashcam footage
`auto`	videotoolbox → x265 → x264	varies	varies	Cross-platform or unknown machine
`quality`	libx265 (CRF 20)	~50s	~80W	Archival, cinema, complex sources
`compat`	libx264 (CRF 19)	~30s	~70W	Older TVs, players without HEVC support

* Measured on Apple Silicon MacBook Pro.

CLI Reference

Options:
  -s, --source, --input DIR       Source directory or single file (default: current directory)
  -d, --destination, --output DIR Destination directory (default: current directory)
  --mode MODE                     hardware|auto|quality|compat (default: hardware)
  --crf N                         CRF for quality/compat modes (lower = better; default: 20/19)
  --no-overwrite                  Skip files that already exist at destination
  --dry-run                       Print actions without writing files
  --no-recursive                  Process only the top-level source directory
  --extensions LIST               Comma-separated extensions (default: mp4,mov,avi,m4v)
  --verbose                       Full per-operation logs + ffmpeg/ffprobe output
  --move-source                   Delete source after strict post-encode validation
  -h, --help                      Show full help with encoding mode details

Output Conventions

Output is always .mp4
HEVC outputs tagged hvc1 (required for Apple Photos / QuickTime)
Directory structure under source is preserved at destination
File timestamps copied from source (touch -r)
JSON sidecars copied 1:1 to destination
telemetry_manifest.json written to destination as a placeholder for a future FIT sync pipeline

Output Format (quiet mode, default)

2026-05-04 12:08:00 : Transcoding SampleFootage/Day/2026-04-04_18-10-36.mp4 ... done in 5s
2026-05-04 12:08:04 : Transcoding SampleFootage/Day/2026-04-04_18-10-05.mp4 ... done in 4s
[2026-05-04 12:08:35] [INFO] Summary: videos_processed=10 videos_skipped=0 errors=0
[2026-05-04 12:08:35] [INFO] Timing: total_elapsed=44s, video_encode_avg=4s

Safety

Destination inside source is rejected with an error
--move-source only deletes source after codec + duration validation passes
--dry-run never writes files

Source Files

SampleFootage/          Original clips (gitignored)
Output/                 Transcoded output (gitignored)
garmin_varia_transcode.sh   Main script
CHANGELOG.md            Version history
DEVLOG.md               Development decisions and rationale