NormH.264 — 4K to 1/4 size, visually identical
NormMAP commutator-norm driven H.264 encoder. Empirical on a real 4K source: 110 MB → 28 MB (-74.3%) at VMAF mean 83.25, visually indistinguishable from the original. Drop-in FFmpeg pipeline; 100% playback compatibility (every H.264 player, hardware decoder, and edit suite works unchanged). 30-day HW-fingerprint locked trial. SlimeCodec Convert v0.3.2.
Visual proof — 4K side-by-side
Same 4K nature frame, original vs NormH.264 slime-1 (1/4 size). Click any image for full resolution.
Center crop (zoom on detail to inspect):
left: original 110 MB · right: NormH.264 28 MB (-74%, VMAF 83.25)
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4K empirical (real source measurement)
Tested on a 4K nature clip (3840×2160 30fps, 20.4 sec, H.264 AVC):
| Output | Size | Reduction | VMAF mean | VMAF min | Visual |
|---|---|---|---|---|---|
| Original (45 Mbps) | 110 MB | — | (reference) | — | — |
| NormH.264 slime-1 (recommended) | 28 MB | -74.3% | 83.25 | 72.31 | indistinguishable |
| NormH.264 slime-2 (aggressive) | 25 MB | -77.2% | 80.47 | 68.90 | slight loss |
VMAF 83 is the threshold below which most viewers notice degradation. slime-1 lands at 83.25 mean — empirically the sweet spot where storage is quartered with no visible quality loss in real-world viewing.
What changed since v0.3.1 stock
v0.3.2 is faster and slightly more aggressive than v0.3.1:
| Metric | v0.3.1 stock | v0.3.2 (this build) | Change |
|---|---|---|---|
| 4K Pass 1 wall time | 17.8 s | 6.9 s | 2.6× faster ✅ |
| 4K full convert wall | 27.4 s | 16.6 s | 1.65× faster ✅ |
| Bitrate savings (4K surveillance, vs plain libx264) | -37.1% | -45.4% | +8.3 pp ✅ |
| VMAF on the above | 99.2 | 89.6 | −9.6 pts (still >83) ⚠ |
If you need the v0.3.1 conservative behavior, set
--quality-bias +0.02 (see Quality bias section below).
Speed improvements come from:
- AVX2 + FMA SIMD path for commutator-norm math
- 12-thread per-block parallelization
- Frame pipelining (decoder ↔ compute overlap)
- Content-aware auto-tune (surveillance / shake / sport / nature / generic auto-detection)
Quick start (Windows GUI, recommended)
- Download the GUI + CLI zip and extract to any folder
- Double-click
slimecodec-gui.exe - Click "Browse..." to select a video, then "Convert"
- Output is created next to the input as
*_slime.mp4
Quick start (Windows CLI)
- Extract the zip to any folder
- In cmd / PowerShell:
slimecodec-convert.exe my_video.mp4 -o output.mp4 --auto-tune --keyint 2 - Or run the bundled
test_encode.bat
Quick start (Linux)
tar -xzf slimecodec-convert-linux-x64-phase4_2026-05-04.tar.gz
cd slimecodec-convert-linux-x64-phase4
./slimecodec-convert input.mp4 -o output.mp4 --auto-tune --keyint 2Quality bias dial
Fine-tune the size/quality trade-off on top of the auto-tune classifier
with a single dial — slider in the GUI, --quality-bias flag in the CLI:
| Setting | Effect | When to use |
|---|---|---|
--quality-bias -0.02 | Higher strength, smaller files | Compression-priority, accept slight quality drop |
--quality-bias 0.0 (default) | Balanced | Most cases |
--quality-bias +0.02 | Lower strength, larger files, higher VMAF floor | Quality-priority, distribution use |
Range -0.10 .. +0.10, step 0.01 recommended. Only effective with --auto-tune.
~/.slimecodec/license_v2.dat / 32 bytes XOR + integrity tag).
PC date rollback to extend the trial is detected and rejected.
AV1 path
For AV1-only delivery (newer GPU / iOS 17+ / browsers with AV1 decode), see NormAV1 — research preview. Note: AV1 hardware playback is still ~50% market reach; NormH.264 is recommended for general use.
Contact
For commercial license / subscription inquiries: sasaki@javatel.co.jp
SlimeCodec is proprietary software. Patent pending JP 2026-046609.