ffvm

A CLI tool for encoding videos with ffmpeg and scoring quality with VMAF. Supports single files, batch processing, and automatic CRF sweeping to hit a target VMAF score.

Installation

Requires ffmpeg (built with libvmaf) and ffprobe in PATH.

pip install ffvm

Commands

encode

Encode a single video file.

ffvm encode input.mp4 output.mp4 --vcodec libsvtav1 --crf 28 --preset 5 --extra "-svtav1-params tune=0:enable-qm=1:qm-min=0" --extra "-write_tmcd 0"

Options:

• --vcodec — Video codec: copy, libx264, libx265, libsvtav1, libvpx-vp9, libaom-av1, librav1e (default: libx264)
• --crf — Constant Rate Factor (default: 23)
• --preset — Encoder preset, e.g. 5
• --extra — Extra ffmpeg arguments (repeatable), e.g. --extra "-svtav1-params tune=0"
• --acodec — Audio codec: copy, aac, libopus, libvorbis, flac, pcm_s16le, libmp3lame (default: copy)
• --ab — Audio bitrate, e.g. 160k
• --resolution — Output resolution, e.g. 1920x1080
• --compare — Run VMAF comparison after encoding

batch

Encode all videos in a directory.

ffvm batch ./videos --vcodec libsvtav1 --crf 30 --compare

Output files are named {original}_{codec}_{crf}.{ext}. Additional options:

• --output-dir — Write encoded files to a different directory
• --recursive — Search subdirectories for videos
• --overwrite — Skip overwrite confirmations
• --compare — Run VMAF on each encode and display a results table

sweep

Find the optimal CRF for a video using binary search against a VMAF target. Extracts representative segments, tests CRF values, and encodes the full video at the best CRF found.

ffvm sweep input.mp4 output.mp4 --target-vmaf 95.0 --crf-min 20 --crf-max 35

Options:

• --target-vmaf — Target VMAF score (default: 93.0)
• --crf-min — Lower bound of CRF search range (default: 23)
• --crf-max — Upper bound of CRF search range (default: 32)

batch-sweep

Run CRF sweep on every video in a directory. Each video gets its own optimal CRF.

ffvm batch-sweep ./videos --vcodec libsvtav1 --target-vmaf 95.0

How sweep works

1. Extracts 1-7 short segments (scaled by video length) from the middle 80% of the video
2. Binary searches through the CRF range, encoding and VMAF-scoring each segment per iteration
3. Converges when crf_max - crf_min <= 1
4. Encodes the full video at the resulting CRF

Roadmap

• RAM disk support for intermediate files
• Test suite (unit tests for pure functions, integration tests for encode pipeline)
• Better error handling for ffmpeg subprocess failures
• Robust VMAF score parsing
• Logging for long-running operations (sweep, batch)
• UI improvements (progress display, summary tables)