decoder-svideo-to-modulated-chroma

This shader takes an input S-Video signal and modulates the chroma channel with a reference waveform (relative to the per-scanline phase) in preparation for getting the I and Q chroma channels (of the YIQ color space) for conversion to RGB.

This is essentially a pre-pass for svideo-to-rgb, to avoid doing (with the standard filter sizes) 8 sines and cosines per output texel from that shader.

Index

Input Textures/Samplers

Uniform Buffer Values

Input Textures/Samplers

g_sourceTexture
                g_sourceTexture
Type
texture (platform-specific)
Description
This is a 2- or 4-component texture that contains either a single luma, chroma sample pair or two luma, chroma pairs of S-Video-like signal. It is 2 components if we have no temporal aliasing reduction (we're not blending two versions of the same frame), 4 components if we do.
g_sourceSampler
                g_sourceSampler
Type
sampler (platform-specific, does not exist on some platforms)
Description

The sampler to use to sample g_sourceTexture.

This sampler should be set up for linear filtering and clamped addressing (no wrapping).

g_scanlinePhases
                g_scanlinePhases
Type
texture (platform-specific)
Description

This is a 1- or 2-component texture that contains the colorburst phase offsets for each scanline. It's 1 component if we have no temporal artifact reduction, and 2 if we do.

Each phase value in this texture is the phase in (fractional) multiples of the colorburst wavelength.

g_scanlinePhasesSampler
                g_scanlinePhasesSampler
Type
sampler (platform-specific, does not exist on some platforms)
Description

The sampler to use to sample g_scanlinePhases.

This sampler should be set up for linear filtering and clamped addressing (no wrapping).

Uniform Buffer Values

g_samplesPerColorburstCycle
                uint g_samplesPerColorburstCycle
Type
uint
Description
How many samples (horizontal texels) there are per each color wave cycle.
g_tint
                float g_tint
Type
float
Description

A value representing the tint offset (in colorburst wavelengths) from baseline that we want to use. Mostly used for fun to emulate the tint dial of a CRT TV.

A value of 0.0 represents using the standard decoded colors.

g_inputWidth
                uint g_filterDir
Type
uint
Description
The width of the input signal (in texels).