Build-time utilities for VNEF media.

Converts input videos to VP9 WebM and wraps them into a simple .video container:

• 4 bytes magic: VID0
• 4 bytes version (uint32 LE, 1)
• 8 bytes webm size (uint64 LE)
• raw WebM bytes

# Run directly
odin run build_videos.odin -file -- <input-file-or-dir> <output-dir> --recursive

# Or build a binary
odin build build_videos.odin -out:build_videos
./build_videos <input-file-or-dir> <output-dir> --recursive

Common options:

• --audio extract audio to .ogg (Opus)
• --audio-out <dir> output directory for extracted audio
• --keep-webm keep intermediate .webm
• --force overwrite outputs
• --ffmpeg /path/to/ffmpeg use a specific ffmpeg binary

Requires ffmpeg in PATH (or bundled under third_party/ffmpeg).

• Source videos: demo/assets/videos_src/ (mp4/webm)
• Generated videos: demo/runtime/videos/ (.video)
• Extracted audio: demo/runtime/video_audio/ (.ogg)

Python fallback with the same behavior. Prefer the Odin tool.

If you bundle FFmpeg binaries, follow the checklist in THIRD_PARTY.md and third_party/ffmpeg/README.md.