mxl-multiviewer/PixelFormat.hpp

#pragma once

#include <cstdint>

struct RgbColor
{
    uint8_t r = 0;
    uint8_t g = 0;
    uint8_t b = 0;
};

inline uint32_t packRgba8(RgbColor color)
{
    constexpr uint8_t alpha = 255;

    return (alpha << 24) |
           (color.b << 16) |
           (color.g << 8) |
           color.r;
}

inline uint8_t clampUint8(int32_t v)
{
    return static_cast<uint8_t>(
        v < 0 ? 0 : (v > 255 ? 255 : v)
    );
}

inline uint32_t v210LineStride(uint32_t width)
{
    uint32_t groups = (width + 5) / 6;
    uint32_t rawBytes = groups * 16;
    return ((rawBytes + 127) / 128) * 128;
}

inline void decodeV210Line(
    const uint8_t* lineData,
    uint32_t* rgbaLine,
    uint32_t width)
{
    for (uint32_t x = 0; x < width; ++x)
    {
        uint32_t group = x / 6;
        uint32_t pos = x % 6;

        const uint32_t baseOffset = group * 16;
        uint32_t w0;
        uint32_t w1;
        uint32_t w2;
        uint32_t w3;

        const uint8_t* p = lineData + baseOffset;
        w0 = static_cast<uint32_t>(p[0]) |
             (static_cast<uint32_t>(p[1]) << 8) |
             (static_cast<uint32_t>(p[2]) << 16) |
             (static_cast<uint32_t>(p[3]) << 24);
        w1 = static_cast<uint32_t>(p[4]) |
             (static_cast<uint32_t>(p[5]) << 8) |
             (static_cast<uint32_t>(p[6]) << 16) |
             (static_cast<uint32_t>(p[7]) << 24);
        w2 = static_cast<uint32_t>(p[8]) |
             (static_cast<uint32_t>(p[9]) << 8) |
             (static_cast<uint32_t>(p[10]) << 16) |
             (static_cast<uint32_t>(p[11]) << 24);
        w3 = static_cast<uint32_t>(p[12]) |
             (static_cast<uint32_t>(p[13]) << 8) |
             (static_cast<uint32_t>(p[14]) << 16) |
             (static_cast<uint32_t>(p[15]) << 24);

        uint32_t cb0 = (w0 >> 0) & 0x3FF;
        uint32_t y0  = (w0 >> 10) & 0x3FF;
        uint32_t cr0 = (w0 >> 20) & 0x3FF;
        uint32_t y1  = (w1 >> 0) & 0x3FF;
        uint32_t cb2 = (w1 >> 10) & 0x3FF;
        uint32_t y2  = (w1 >> 20) & 0x3FF;
        uint32_t cr2 = (w2 >> 0) & 0x3FF;
        uint32_t y3  = (w2 >> 10) & 0x3FF;
        uint32_t cb4 = (w2 >> 20) & 0x3FF;
        uint32_t y4  = (w3 >> 0) & 0x3FF;
        uint32_t cr4 = (w3 >> 10) & 0x3FF;
        uint32_t y5  = (w3 >> 20) & 0x3FF;

        uint32_t y10;
        uint32_t cb10;
        uint32_t cr10;

        switch (pos)
        {
            case 0: y10 = y0; cb10 = cb0; cr10 = cr0; break;
            case 1: y10 = y1; cb10 = cb0; cr10 = cr0; break;
            case 2: y10 = y2; cb10 = cb2; cr10 = cr2; break;
            case 3: y10 = y3; cb10 = cb2; cr10 = cr2; break;
            case 4: y10 = y4; cb10 = cb4; cr10 = cr4; break;
            case 5: y10 = y5; cb10 = cb4; cr10 = cr4; break;
            default: y10 = y0; cb10 = cb0; cr10 = cr0; break;
        }

        // BT.709 limited-range YCbCr to RGB. v210 stores 10-bit video-range
        // samples: Y [64, 940], Cb/Cr centered at 512.
        int32_t yp  = (static_cast<int32_t>(y10) - 64) >> 2;
        int32_t cbp = (static_cast<int32_t>(cb10) - 512) >> 2;
        int32_t crp = (static_cast<int32_t>(cr10) - 512) >> 2;

        int32_t r = (298 * yp + 459 * crp + 128) >> 8;
        int32_t g = (298 * yp - 137 * crp - 55 * cbp + 128) >> 8;
        int32_t b = (298 * yp + 541 * cbp + 128) >> 8;

        rgbaLine[x] = packRgba8({clampUint8(r), clampUint8(g), clampUint8(b)});
    }
}

inline void convertV210ToRgba(
    const uint8_t* v210Data,
    uint32_t srcWidth,
    uint32_t srcHeight,
    uint32_t srcStride,
    uint32_t* rgbaData,
    uint32_t dstWidth,
    uint32_t dstHeight)
{
    for (uint32_t dy = 0; dy < dstHeight; ++dy)
    {
        uint32_t sy = dy * srcHeight / dstHeight;

        const uint8_t* srcLine = v210Data + sy * srcStride;

        for (uint32_t dx = 0; dx < dstWidth; ++dx)
        {
            uint32_t sx = dx * srcWidth / dstWidth;

            uint32_t group = sx / 6;
            uint32_t pos = sx % 6;

            const uint8_t* p = srcLine + group * 16;
            uint32_t w0 = static_cast<uint32_t>(p[0]) |
                          (static_cast<uint32_t>(p[1]) << 8) |
                          (static_cast<uint32_t>(p[2]) << 16) |
                          (static_cast<uint32_t>(p[3]) << 24);
            uint32_t w1 = static_cast<uint32_t>(p[4]) |
                          (static_cast<uint32_t>(p[5]) << 8) |
                          (static_cast<uint32_t>(p[6]) << 16) |
                          (static_cast<uint32_t>(p[7]) << 24);
            uint32_t w2 = static_cast<uint32_t>(p[8]) |
                          (static_cast<uint32_t>(p[9]) << 8) |
                          (static_cast<uint32_t>(p[10]) << 16) |
                          (static_cast<uint32_t>(p[11]) << 24);
            uint32_t w3 = static_cast<uint32_t>(p[12]) |
                          (static_cast<uint32_t>(p[13]) << 8) |
                          (static_cast<uint32_t>(p[14]) << 16) |
                          (static_cast<uint32_t>(p[15]) << 24);

            uint32_t cb0 = (w0 >> 0) & 0x3FF;
            uint32_t y0  = (w0 >> 10) & 0x3FF;
            uint32_t cr0 = (w0 >> 20) & 0x3FF;
            uint32_t y1  = (w1 >> 0) & 0x3FF;
            uint32_t cb2 = (w1 >> 10) & 0x3FF;
            uint32_t y2  = (w1 >> 20) & 0x3FF;
            uint32_t cr2 = (w2 >> 0) & 0x3FF;
            uint32_t y3  = (w2 >> 10) & 0x3FF;
            uint32_t cb4 = (w2 >> 20) & 0x3FF;
            uint32_t y4  = (w3 >> 0) & 0x3FF;
            uint32_t cr4 = (w3 >> 10) & 0x3FF;
            uint32_t y5  = (w3 >> 20) & 0x3FF;

            uint32_t y10;
            uint32_t cb10;
            uint32_t cr10;

            switch (pos)
            {
                case 0: y10 = y0; cb10 = cb0; cr10 = cr0; break;
                case 1: y10 = y1; cb10 = cb0; cr10 = cr0; break;
                case 2: y10 = y2; cb10 = cb2; cr10 = cr2; break;
                case 3: y10 = y3; cb10 = cb2; cr10 = cr2; break;
                case 4: y10 = y4; cb10 = cb4; cr10 = cr4; break;
                case 5: y10 = y5; cb10 = cb4; cr10 = cr4; break;
                default: y10 = y0; cb10 = cb0; cr10 = cr0; break;
            }

            // BT.709 limited-range YCbCr to RGB. v210 stores 10-bit video-range
            // samples: Y [64, 940], Cb/Cr centered at 512.
            int32_t yp  = (static_cast<int32_t>(y10) - 64) >> 2;
            int32_t cbp = (static_cast<int32_t>(cb10) - 512) >> 2;
            int32_t crp = (static_cast<int32_t>(cr10) - 512) >> 2;

            int32_t r = (298 * yp + 459 * crp + 128) >> 8;
            int32_t g = (298 * yp - 137 * crp - 55 * cbp + 128) >> 8;
            int32_t b = (298 * yp + 541 * cbp + 128) >> 8;

            rgbaData[dy * dstWidth + dx] = packRgba8(
                {clampUint8(r), clampUint8(g), clampUint8(b)});
        }
    }
}