SSIMULACRA2
December 18, 2025 ยท View on GitHub
Overview of SSIMULACRA2
SSIMULACRA2 is a colorspace aware metric which tries to correlate with MOS on a wide quality range using similar technics as VMAF or MSSIM.
Arguments
| Name | Type | Required | Default |
|---|---|---|---|
| reference | vapoursynth.VideoNode | Yes | |
| distorted | vapoursynth.VideoNode | Yes | |
| numStream | int | No | core.num_threads |
| gpu_id | int | No | 0 |
reference
Reference clip to compare distorted clip to. Must be a VapourSynth VideoNode.
distorted
Distorted clip to compare to reference clip with. It must be a VapourSynth VideoNode with the same length, width, and height as the reference clip.
numStream
It corresponds to the number of concurrent frames running through the GPU at a time. Lowering it allows to control and lower the amount of VRAM consumed. By default, as much stream are created as there are VapourSynth threads. (which is the maximum amount, any higher will get lowered to this value)
gpu_id
ID of the GPU to run VSHIP on. It will perform the GPU Check functions as described in the Error Management page.
SSIMULACRA2 Return Values
The method will always return a VapourSynth VideoNode with the following property on each individual [VideoFrame][vs-videoframe]: _SSIMULACRA2
VRAM Consumption
VRAM consumption can be calculated using the following: 9 * 4 * width * height * 4/3 where width and height refer to the dimensions of the video. Bytes per VapourSynth thread: Plane Buffer * sizeof(float) * width * height * 4/3.