Ssim360

Video Single output Transform

Calculate the SSIM between two 360 video streams.

FFmpeg filter: ssim360 — the official reference.

Add it to a graph. The explicit form works for every filter — bind it to its inputs and read the result from outputs():

$node   = $video->addFilter(new Ssim360(…), [$other]);
$result = $node->outputs()[0];

Shorthand. Single-output filters can skip the node — apply() returns the result stream directly:

$result = $video->apply(new Ssim360(…), $other);

When to use it

TODO — when this filter shines: what it’s the right tool for, what to reach for instead when it isn’t, and how it composes with neighbouring filters.

How to use it

TODO — prose: how the filter actually works and what its key parameters mean (the explanation FFmpeg’s terse option help omits).

Examples

TODO — runnable PHP, with the equivalent ffmpeg CLI alongside.

Gotchas

TODO

See also

TODO

Parameters

Parameter	Type	Default	Range / values	Description
stats_file	string	—	—	Set file where to store per-frame difference information
compute_chroma	int	1	0–1	Specifies if non-luma channels must be computed
frame_skip_ratio	int	0	0–1000000	Specifies the number of frames to be skipped from evaluation, for every evaluated frame
ref_projection	Ssim360Projection	equirect	equirect, c3x2, c2x3, barrel, barrelsplit	projection of the reference video
main_projection	Ssim360Projection	5	equirect, c3x2, c2x3, barrel, barrelsplit	projection of the main video
ref_stereo	Ssim360StereoFormat	mono	mono, tb, lr	stereo format of the reference video
main_stereo	Ssim360StereoFormat	3	mono, tb, lr	stereo format of main video
ref_pad	float	0	0–10	Expansion (padding) coefficient for each cube face of the reference video
main_pad	float	0	0–10	Expansion (padding) coeffiecient for each cube face of the main video
use_tape	int	0	0–1	Specifies if the tape based SSIM 360 algorithm must be used independent of the input video types
heatmap_str	string	—	—	Heatmap data for view-based evaluation. For heatmap file format, please refer to EntSphericalVideoHeatmapData.
default_heatmap_width	int	32	1–4096	Default heatmap dimension. Will be used when dimension is not specified in heatmap data.
default_heatmap_height	int	16	1–4096	Default heatmap dimension. Will be used when dimension is not specified in heatmap data.

FFmpeg also names these options (use the parameter shown above): f → stats_file.

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Maps to FFmpeg’s ssim360 filter. Verified against ffmpeg n7.1.1.