CRF vs Bitrate: Which Compression Method Is Better?
Two Philosophies of Video Compression
When compressing video, you face a fundamental choice: do you want to control the file size (bitrate-based encoding) or the visual quality (CRF-based encoding)? Understanding the difference helps you choose the right approach for each situation.
Bitrate-Based Encoding: Controlling File Size
With bitrate-based encoding, you specify the target data rate (e.g., 5 Mbps). The encoder adjusts quality to stay within that budget. If a scene is complex, quality drops. If it is simple, quality rises — but file size remains predictable.
Best for: Streaming platforms, broadcast TV, any scenario where bandwidth or storage is the primary constraint.
Downside: Quality varies unpredictably. A complex action scene may look terrible while a simple static shot wastes bits.
CRF Encoding: Controlling Quality
With CRF (Constant Rate Factor) encoding, you specify the quality level, and the encoder uses whatever bitrate is necessary to achieve it. Simple scenes get fewer bits; complex scenes get more. Quality stays consistent, but file size is unpredictable.
Best for: Archival, personal use, sharing files where you care about quality first.
Downside: You cannot predict the output file size. A very complex video at CRF 18 may produce a much larger file than expected.
CRF Scale Explained
CRF values typically range from 0 to 51, with lower numbers meaning higher quality:
- CRF 0: Lossless (huge files, not practical)
- CRF 18: Near-lossless, suitable for archiving
- CRF 23: Visually lossless for most viewers — the default recommendation
- CRF 28: Noticeable but acceptable quality loss for casual sharing
- CRF 35+: Significant quality loss, only for extreme size constraints
Each increase of 6 CRF roughly halves the bitrate (and file size), while each decrease of 6 roughly doubles it.
When to Use Each Method
Use bitrate encoding when: - You have a strict file size limit - You are preparing video for a streaming platform that specifies target bitrates - You need predictable output sizes for batch processing
Use CRF encoding when: - You care most about consistent visual quality - File size is flexible - You are archiving personal videos - You are compressing for sharing where quality matters more than exact file size
Tooler's Approach
Tooler's Video Compressor uses CRF-based encoding. This aligns with the use case: most people compressing a video for sharing care more about "does it look good?" than "exactly how many megabytes will it be?" The quality slider gives you intuitive control over the quality-size trade-off.