#include "effect_util.h"
#include "resource_pool.h"
#include "util.h"
+#include "ycbcr.h"
#include "ycbcr_input.h"
using namespace Eigen;
namespace movit {
-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;
-}
-
-// Given <ycbcr_format>, compute the values needed to turn Y'CbCr into R'G'B';
-// first subtract the returned offset, then left-multiply the returned matrix
-// (the scaling is already folded into it).
-void compute_ycbcr_matrix(YCbCrFormat ycbcr_format, float* offset, Matrix3d* ycbcr_to_rgb)
-{
- double coeff[3], scale[3];
-
- switch (ycbcr_format.luma_coefficients) {
- case YCBCR_REC_601:
- // Rec. 601, page 2.
- coeff[0] = 0.299;
- coeff[1] = 0.587;
- coeff[2] = 0.114;
- break;
-
- case YCBCR_REC_709:
- // Rec. 709, page 19.
- coeff[0] = 0.2126;
- 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);
- }
-
- if (ycbcr_format.full_range) {
- offset[0] = 0.0 / 255.0;
- offset[1] = 128.0 / 255.0;
- offset[2] = 128.0 / 255.0;
-
- scale[0] = 1.0;
- scale[1] = 1.0;
- scale[2] = 1.0;
- } else {
- // 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;
-
- scale[0] = 255.0 / 219.0;
- scale[1] = 255.0 / 224.0;
- scale[2] = 255.0 / 224.0;
- }
-
- // Matrix to convert RGB to YCbCr. See e.g. Rec. 601.
- Matrix3d rgb_to_ycbcr;
- rgb_to_ycbcr(0,0) = coeff[0];
- rgb_to_ycbcr(0,1) = coeff[1];
- rgb_to_ycbcr(0,2) = coeff[2];
-
- float cb_fac = (224.0 / 219.0) / (coeff[0] + coeff[1] + 1.0f - coeff[2]);
- rgb_to_ycbcr(1,0) = -coeff[0] * cb_fac;
- rgb_to_ycbcr(1,1) = -coeff[1] * cb_fac;
- rgb_to_ycbcr(1,2) = (1.0f - coeff[2]) * cb_fac;
-
- float cr_fac = (224.0 / 219.0) / (1.0f - coeff[0] + coeff[1] + coeff[2]);
- rgb_to_ycbcr(2,0) = (1.0f - coeff[0]) * cr_fac;
- rgb_to_ycbcr(2,1) = -coeff[1] * cr_fac;
- rgb_to_ycbcr(2,2) = -coeff[2] * cr_fac;
-
- // Inverting the matrix gives us what we need to go from YCbCr back to RGB.
- *ycbcr_to_rgb = rgb_to_ycbcr.inverse();
-
- // Fold in the scaling.
- *ycbcr_to_rgb *= Map<const Vector3d>(scale).asDiagonal();
-}
-
-} // namespace
-
YCbCrInput::YCbCrInput(const ImageFormat &image_format,
const YCbCrFormat &ycbcr_format,
unsigned width, unsigned height)
projects / movit / blobdiff