decoder-svideo-to-rgb

This shader takes an input S-Video signal (with separate luma and chroma components) and converts it into an RGB color.

For more information, refer to Decoding A Fake NTSC Signal.

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 artifact reduction (we're not blending two versions of the same frame), 4 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.

g_modulatedChromaTexture
                g_modulatedChromaTexture
Type
texture (platform-specific)
Description

This is a 2- or 4-component texture that contains the output of the svideo-to-modulated-chroma shader (the chroma portions of the input signal modulated with the carrier quadrature). Basically, it's float4(chromaA * sin, chromaA * cos, chromaB * sin, chromaB * cos).

This has been modulated in a separate pass for efficiency - otherwise this shader would need to do a bunch of sines and cosines per texel.

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

The sampler to use to sample g_modulatedChromaTexture.

This sampler should be set up for linear filtering and clamped addressing.

Uniform Buffer Values

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

This is a value representing how saturated we want the output to be. 0 basically means we'll decode as a grayscale image, 1 means fully saturated color (i.e. the intended input saturation), and you could even set values greater than 1 to oversaturate.

This corresponds to the saturation dial of a CRT TV.

NOTE: This value should be pre-scaled by the g_brightness value, so that if brightness is 0, saturation is always 0 - otherwise, you get weird output values where there should have been nothing visible but instead you get a pure color instead.

g_brightness
                float g_brightness
Type
float
Description

This is a value representing the brightness of the output. a value of 0 means the shader will output pure black, and 1 means "the intended brightness based on the input signal". Values above 1 will over-brighten the output.

This corresponds to the brightness dial of a CRT TV.

g_blackLevel
                float g_blackLevel
Type
float
Description

This is the luma value of the input signal that represents black. For our synthetic signals it's typically 0.0, but from a real NTSC signal this can be some other voltage level, since a voltage of 0 typically indicates a horizontal or vertical blank instead.

This is calculated from/generated with the composite or S-Video signal the decoder is given.

g_whiteLevel
                float g_whiteLevel
Type
float
Description

This is the luma value of the input signal that represents brightest white. For our synthetic signals it's typically 1.0, but from a real NTSC signal it could be some other value.

This is calculated from/generated with the composite or S-Video signal the decoder is given.

g_temporalArtifactReduction
                float g_temporalArtifactReduction
Type
float
Description

A [0..1] value indicating how much we want to blend in an alternate version of the generated signal to adjust for any aliasing between successive frames.

A value of 0 means we only have (or want to use) a single input luma/chroma pair. A value greater than 0 means we are going to blend the results of two parallel-computed versions of our RGB values, with a value of 1.0 being a pure average of the two.

g_inputWidth
                uint g_inputWidth
Type
uint
Description
The width of the input signal (including any side padding)
g_outputWidth
                uint g_outputWidth
Type
uint
Description
The width of the output RGB image (should be the width of the input signal minus the side padding).