X-Git-Url: https://git.sesse.net/?p=movit;a=blobdiff_plain;f=ycbcr_input.cpp;h=d1d849a2038e6a0d58958de61954e6d3edab10a0;hp=57fe3f56308acad42983002f8ce20240cc400161;hb=9a00101dbb6f98d21c6b8ce4d33200af840ea908;hpb=9cd94a8a037121e5c919c6969425ef98c8f7165f diff --git a/ycbcr_input.cpp b/ycbcr_input.cpp index 57fe3f5..d1d849a 100644 --- a/ycbcr_input.cpp +++ b/ycbcr_input.cpp @@ -1,14 +1,61 @@ -#include -#include - +#include #include +#include +#include +#include +#include -#include "ycbcr_input.h" +#include "effect_util.h" #include "util.h" -#include "opengl.h" +#include "ycbcr_input.h" using namespace Eigen; +namespace { + +// OpenGL has texel center in (0.5, 0.5), but different formats have +// chroma in various other places. If luma samples are X, the chroma +// sample is *, and subsampling is 3x3, the situation with chroma +// center in (0.5, 0.5) looks approximately like this: +// +// X X +// * +// X X +// +// If, on the other hand, chroma center is in (0.0, 0.5) (common +// for e.g. MPEG-4), the figure changes to: +// +// X X +// * +// X X +// +// In other words, (0.0, 0.0) means that the chroma sample is exactly +// co-sited on top of the top-left luma sample. Note, however, that +// this is _not_ 0.5 texels to the left, since the OpenGL's texel center +// is in (0.5, 0.5); it is in (0.25, 0.25). In a sense, the four luma samples +// define a square where chroma position (0.0, 0.0) is in texel position +// (0.25, 0.25) and chroma position (1.0, 1.0) is in texel position (0.75, 0.75) +// (the outer border shows the borders of the texel itself, ie. from +// (0, 0) to (1, 1)): +// +// --------- +// | | +// | X---X | +// | | * | | +// | X---X | +// | | +// --------- +// +// Also note that if we have no subsampling, the square will have zero +// area and the chroma position does not matter at all. +float compute_chroma_offset(float pos, unsigned subsampling_factor, unsigned resolution) +{ + float local_chroma_pos = (0.5 + pos * (subsampling_factor - 1)) / subsampling_factor; + return (0.5 - local_chroma_pos) / resolution; +} + +} // namespace + YCbCrInput::YCbCrInput(const ImageFormat &image_format, const YCbCrFormat &ycbcr_format, unsigned width, unsigned height) @@ -34,6 +81,8 @@ YCbCrInput::YCbCrInput(const ImageFormat &image_format, heights[1] = height / ycbcr_format.chroma_subsampling_y; heights[2] = height / ycbcr_format.chroma_subsampling_y; + pixel_data[0] = pixel_data[1] = pixel_data[2] = NULL; + register_int("needs_mipmaps", &needs_mipmaps); } @@ -153,6 +202,14 @@ std::string YCbCrInput::output_fragment_shader() coeff[1] = 0.7152; coeff[2] = 0.0722; break; + + case YCBCR_REC_2020: + // Rec. 2020, page 4. + coeff[0] = 0.2627; + coeff[1] = 0.6780; + coeff[2] = 0.0593; + break; + default: assert(false); } @@ -166,7 +223,7 @@ std::string YCbCrInput::output_fragment_shader() scale[1] = 1.0; scale[2] = 1.0; } else { - // Rec. 601, page 4; Rec. 709, page 19. + // Rec. 601, page 4; Rec. 709, page 19; Rec. 2020, page 4. offset[0] = 16.0 / 255.0; offset[1] = 128.0 / 255.0; offset[2] = 128.0 / 255.0; @@ -208,52 +265,20 @@ std::string YCbCrInput::output_fragment_shader() scale[0], scale[1], scale[2]); frag_shader += buf; - // OpenGL has texel center in (0.5, 0.5), but different formats have - // chroma in various other places. If luma samples are X, the chroma - // sample is *, and subsampling is 3x3, the situation with chroma - // center in (0.5, 0.5) looks approximately like this: - // - // X X - // * - // X X - // - // If, on the other hand, chroma center is in (0.0, 0.5) (common - // for e.g. MPEG-4), the figure changes to: - // - // X X - // * - // X X - // - // In other words, (0.0, 0.0) means that the chroma sample is exactly - // co-sited on top of the top-left luma sample. Note, however, that - // this is _not_ 0.5 texels to the left, since the OpenGL's texel center - // is in (0.5, 0.5); it is in (0.25, 0.25). In a sense, the four luma samples - // define a square where chroma position (0.0, 0.0) is in texel position - // (0.25, 0.25) and chroma position (1.0, 1.0) is in texel position (0.75, 0.75) - // (the outer border shows the borders of the texel itself, ie. from - // (0, 0) to (1, 1)): - // - // --------- - // | | - // | X---X | - // | | * | | - // | X---X | - // | | - // --------- - // - // Also note that if we have no subsampling, the square will have zero - // area and the chroma position does not matter at all. - float chroma_x_local_position = - (0.5 + ycbcr_format.chroma_x_position * (ycbcr_format.chroma_subsampling_x - 1)) / - ycbcr_format.chroma_subsampling_x; - float chroma_y_local_position = - (0.5 + ycbcr_format.chroma_y_position * (ycbcr_format.chroma_subsampling_y - 1)) / - ycbcr_format.chroma_subsampling_y; - - float chroma_offset_x = (0.5f - chroma_x_local_position) / widths[1]; - float chroma_offset_y = (0.5f - chroma_y_local_position) / heights[1]; - sprintf(buf, "const vec2 PREFIX(chroma_offset) = vec2(%.8f, %.8f);\n", - chroma_offset_x, chroma_offset_y); + float cb_offset_x = compute_chroma_offset( + ycbcr_format.cb_x_position, ycbcr_format.chroma_subsampling_x, widths[1]); + float cb_offset_y = compute_chroma_offset( + ycbcr_format.cb_y_position, ycbcr_format.chroma_subsampling_y, heights[1]); + sprintf(buf, "const vec2 PREFIX(cb_offset) = vec2(%.8f, %.8f);\n", + cb_offset_x, cb_offset_y); + frag_shader += buf; + + float cr_offset_x = compute_chroma_offset( + ycbcr_format.cr_x_position, ycbcr_format.chroma_subsampling_x, widths[2]); + float cr_offset_y = compute_chroma_offset( + ycbcr_format.cr_y_position, ycbcr_format.chroma_subsampling_y, heights[2]); + sprintf(buf, "const vec2 PREFIX(cr_offset) = vec2(%.8f, %.8f);\n", + cr_offset_x, cr_offset_y); frag_shader += buf; frag_shader += read_file("ycbcr_input.frag");