Struct QualityMetrics 

pub struct QualityMetrics;

Computes video quality metrics between a reference and a distorted video.

All methods are static — there is no state to configure.

Implementations

impl QualityMetrics

pub fn ssim( reference: impl AsRef<Path>, distorted: impl AsRef<Path>, ) -> Result<f32, FilterError>

Computes the mean SSIM (Structural Similarity Index Measure) over all frames between reference and distorted.

Returns a value in [0.0, 1.0]:

• 1.0 — the inputs are frame-identical.
• 0.0 — no structural similarity.

Uses FFmpeg’s ssim filter internally. Both inputs must have the same frame count; if they differ the function returns an error rather than silently comparing only the overlapping portion.

Errors

• FilterError::AnalysisFailed — either input file is not found, the inputs have different frame counts, or the internal filter graph fails.

Examples

use ff_filter::QualityMetrics;

// Compare a video against itself — should return ≈ 1.0.
let ssim = QualityMetrics::ssim("reference.mp4", "reference.mp4")?;
assert!(ssim > 0.9999);

pub fn psnr( reference: impl AsRef<Path>, distorted: impl AsRef<Path>, ) -> Result<f32, FilterError>

Computes the mean PSNR (Peak Signal-to-Noise Ratio, in dB) over all frames between reference and distorted.

Uses the luminance (Y-plane) PSNR as the representative value.

• Identical inputs → f32::INFINITY (MSE = 0).
• Lightly compressed → typically > 40 dB.
• Heavy degradation → typically < 30 dB.

Uses FFmpeg’s psnr filter internally. Both inputs must have the same frame count; if they differ the function returns an error.

Errors

• FilterError::AnalysisFailed — either input file is not found, the inputs have different frame counts, or the internal filter graph fails.

Examples

use ff_filter::QualityMetrics;

// Compare a video against itself — should return infinity.
let psnr = QualityMetrics::psnr("reference.mp4", "reference.mp4")?;
assert!(psnr > 100.0 || psnr == f32::INFINITY);