The twenty-twenty library allows for visual regression testing of H.264 frames and images.
It makes it easy to update the contents when should be updated to match the new results.
Each function takes a score threshold, which is the lowest possible "score" you are willing for the image comparison to return. If the resulting score is less than than the threshold, the test will fail. The score must be a number between 0 and 1. If the images are the exact same, the score will be 1.
The underlying algorithm is SSIM, which is a perceptual metric that quantifies the image quality degradation that is caused by processing such as data compression or by losses in data transmission. More information can be found here.
Use it like this for an H.264 frame:
```rust
let (width, height, actual) = getframe(); twentytwenty::asserth264frame("frame_image.png", width, height, &actual, 0.9); ``` Use it like this for an image:
```rust
let actual = getimage(); twentytwenty::assertimage("ogimage.png", &actual, 0.9); ```
If the output doesn't match, the program will panic! and emit the
difference in the score.
To accept the changes from get_frame() or get_image(), run with TWENTY_TWENTY=overwrite.