This is a blend file that contains a compositing set up that simulates different physical aspects of VHS tapes, and a bash script that renders an interlaced video file to match the [480i NTSC standard](https://en.wikipedia.org/wiki/480i). Many physical aspects of the tape simulation are recreated from the descriptions in [Scotch Video Tapes 1980's VHS Primer](https://youtu.be/Cj0lvGqTkD0) video.

[This file is part of a collection of files that includes test footage and a bash script.](https://github.com/wagesj45/blender-vhs-simulator)

## Nodes

### Crop and Scale

This node contains sub-nodes to crop the input image/clip to a 4:3 ratio, then scale that cropped image to the `Resolution X` and `Resolution Y` of the Scene's dimensions.

### Luma to Chroma Ratio

This node reduces the color information in relation to the luminance information in the image to fit the [ratio supported by VHS tape](https://en.wikipedia.org/wiki/VHS#Video_recording).

### Video Frequency Response
[Video frequency response](https://youtu.be/Cj0lvGqTkD0?t=948) measures how well picture detail is reproduced.

### Signal to Noise Ratio

This node simulates the signal to noise ratio of data held by the magnetic tape. A higher dB value results in a higher quality image. This can be adjusted for both the luma signal and the chroma signal separately.

### Color Bleed

This node simulates CRT-like RGB color bleed onto other pixels. The bleed per color can be dialed up and down.

### Phase Modulation Noise

[Phase modulation noise](https://youtu.be/Cj0lvGqTkD0?t=846) simulates color banding seen in degraded tape. Banding can be controlled by intensity, offset, and scale which correlates to the number of bands seen. A lower scale makes the bands larger, and a larger scale makes the bands thinner but increases their number.

### Chroma Output

[Chroma output](https://youtu.be/Cj0lvGqTkD0?t=879) is a measure of the chroma saturation of the image.

### Video RF Output

[Video RF output](https://youtu.be/Cj0lvGqTkD0?t=894) is the maximum amount of playback signal compared to that of a reference tape.

### Dropouts

[Dropouts](https://youtu.be/Cj0lvGqTkD0?t=970) are an artifact generated by video head / tape separation.