Add YCbCr input. Required a bit of reworking of the sRGB extension stuff, but seems...
authorSteinar H. Gunderson <sgunderson@bigfoot.com>
Sun, 7 Oct 2012 10:32:30 +0000 (12:32 +0200)
committerSteinar H. Gunderson <sgunderson@bigfoot.com>
Sun, 7 Oct 2012 10:32:30 +0000 (12:32 +0200)
effect_chain.cpp
effect_chain.h
flat_input.cpp
flat_input.h
image_format.h
input.h
ycbcr_input.cpp [new file with mode: 0644]
ycbcr_input.frag [new file with mode: 0644]
ycbcr_input.h [new file with mode: 0644]

index 82e9c5d..13f4634 100644 (file)
@@ -60,48 +60,70 @@ void EffectChain::add_effect_raw(Effect *effect, const std::vector<Effect *> &in
        output_color_space[effect] = output_color_space[last_added_effect()];
 }
 
-// Set the "use_srgb_texture_format" option on all inputs that feed into this node,
-// and update the output_gamma_curve[] map as we go.
-//
-// NOTE: We assume that the only way we could actually get GAMMA_sRGB from an
-// effect (except from GammaCompressionCurve, which should never be inserted
-// into a chain when this is called) is by pass-through from a texture.
-// Thus, we can simply feed the flag up towards all inputs.
-void EffectChain::set_use_srgb_texture_format(Effect *effect)
+void EffectChain::find_all_nonlinear_inputs(Effect *effect,
+                                            std::vector<Input *> *nonlinear_inputs,
+                                            std::vector<Effect *> *intermediates)
 {
        assert(output_gamma_curve.count(effect) != 0);
-       assert(output_gamma_curve[effect] == GAMMA_sRGB);
+       if (output_gamma_curve[effect] == GAMMA_LINEAR) {
+               return;
+       }
        if (effect->num_inputs() == 0) {
-               effect->set_int("use_srgb_texture_format", 1);
+               nonlinear_inputs->push_back(static_cast<Input *>(effect));
        } else {
+               intermediates->push_back(effect);
+
                assert(incoming_links.count(effect) == 1);
                std::vector<Effect *> deps = incoming_links[effect];
                assert(effect->num_inputs() == deps.size());
                for (unsigned i = 0; i < deps.size(); ++i) {
-                       set_use_srgb_texture_format(deps[i]);
-                       assert(output_gamma_curve[deps[i]] == GAMMA_LINEAR);
+                       find_all_nonlinear_inputs(deps[i], nonlinear_inputs, intermediates);
                }
        }
-       output_gamma_curve[effect] = GAMMA_LINEAR;
 }
 
 Effect *EffectChain::normalize_to_linear_gamma(Effect *input)
 {
-       assert(output_gamma_curve.count(input) != 0);
-       if (output_gamma_curve[input] == GAMMA_sRGB) {
-               // TODO: check if the extension exists
-               set_use_srgb_texture_format(input);
-               output_gamma_curve[input] = GAMMA_LINEAR;
+       // Find out if all the inputs can be set to deliver sRGB inputs.
+       // If so, we can just ask them to do that instead of inserting a
+       // (possibly expensive) conversion operation.
+       //
+       // NOTE: We assume that effects generally don't mess with the gamma
+       // curve (except GammaCompressionEffect, which should never be
+       // inserted into a chain when this is called), so that we can just
+       // update the output gamma as we go.
+       //
+       // TODO: Setting this flag for one source might confuse a different
+       // part of the pipeline using the same source.
+       std::vector<Input *> nonlinear_inputs;
+       std::vector<Effect *> intermediates;
+       find_all_nonlinear_inputs(input, &nonlinear_inputs, &intermediates);
+
+       bool all_ok = true;
+       for (unsigned i = 0; i < nonlinear_inputs.size(); ++i) {
+               all_ok &= nonlinear_inputs[i]->can_output_linear_gamma();
+       }
+
+       if (all_ok) {
+               for (unsigned i = 0; i < nonlinear_inputs.size(); ++i) {
+                       bool ok = nonlinear_inputs[i]->set_int("output_linear_gamma", 1);
+                       assert(ok);
+                       output_gamma_curve[nonlinear_inputs[i]] = GAMMA_LINEAR;
+               }
+               for (unsigned i = 0; i < intermediates.size(); ++i) {
+                       output_gamma_curve[intermediates[i]] = GAMMA_LINEAR;
+               }
                return input;
-       } else {
-               GammaExpansionEffect *gamma_conversion = new GammaExpansionEffect();
-               gamma_conversion->set_int("source_curve", output_gamma_curve[input]);
-               std::vector<Effect *> inputs;
-               inputs.push_back(input);
-               gamma_conversion->add_self_to_effect_chain(this, inputs);
-               output_gamma_curve[gamma_conversion] = GAMMA_LINEAR;
-               return gamma_conversion;
        }
+
+       // OK, that didn't work. Insert a conversion effect.
+       GammaExpansionEffect *gamma_conversion = new GammaExpansionEffect();
+       gamma_conversion->set_int("source_curve", output_gamma_curve[input]);
+       std::vector<Effect *> inputs;
+       inputs.push_back(input);
+       gamma_conversion->add_self_to_effect_chain(this, inputs);
+       output_gamma_curve[gamma_conversion] = GAMMA_LINEAR;
+       return gamma_conversion;
 }
 
 Effect *EffectChain::normalize_to_srgb(Effect *input)
index 0b07b85..6795578 100644 (file)
@@ -69,7 +69,9 @@ private:
                std::vector<Effect *> effects;  // In order.
        };
 
-       void set_use_srgb_texture_format(Effect *effect);
+       void find_all_nonlinear_inputs(Effect *effect,
+                                      std::vector<Input *> *nonlinear_inputs,
+                                      std::vector<Effect *> *intermediates);
        Effect *normalize_to_linear_gamma(Effect *input);
        Effect *normalize_to_srgb(Effect *input);
 
index 2541dc4..c7f417b 100644 (file)
@@ -12,13 +12,13 @@ FlatInput::FlatInput(ImageFormat image_format, unsigned width, unsigned height)
        : image_format(image_format),
          needs_update(false),
          finalized(false),
-         use_srgb_texture_format(false),
+         output_linear_gamma(false),
          needs_mipmaps(false),
          width(width),
          height(height),
          pitch(width)
 {
-       register_int("use_srgb_texture_format", &use_srgb_texture_format);
+       register_int("output_linear_gamma", &output_linear_gamma);
        register_int("needs_mipmaps", &needs_mipmaps);
 }
 
@@ -26,7 +26,7 @@ void FlatInput::finalize()
 {
        // Translate the input format to OpenGL's enums.
        GLenum internal_format;
-       if (use_srgb_texture_format) {
+       if (output_linear_gamma) {
                internal_format = GL_SRGB8;
        } else {
                internal_format = GL_RGBA8;
index a906a5d..69c1a6f 100644 (file)
@@ -14,13 +14,16 @@ public:
        // mipmap generation) at that point.
        void finalize();
 
+       // TODO: Check that we actually have the required extension.
+       virtual bool can_output_linear_gamma() const { return true; }
+
        std::string output_fragment_shader();
 
        // Uploads the texture if it has changed since last time.
        void set_gl_state(GLuint glsl_program_num, const std::string& prefix, unsigned *sampler_num);
 
-       ColorSpace get_color_space() { return image_format.color_space; }
-       GammaCurve get_gamma_curve() { return image_format.gamma_curve; }
+       ColorSpace get_color_space() const { return image_format.color_space; }
+       GammaCurve get_gamma_curve() const { return image_format.gamma_curve; }
 
        // Tells the input where to fetch the actual pixel data. Note that if you change
        // this data, you must either call set_pixel_data() again (using the same pointer
@@ -56,7 +59,7 @@ private:
        GLenum format;
        GLuint pbo, texture_num;
        bool needs_update, finalized;
-       int use_srgb_texture_format, needs_mipmaps;
+       int output_linear_gamma, needs_mipmaps;
        unsigned width, height, pitch, bytes_per_pixel;
        const unsigned char *pixel_data;
 };
index 346cdef..2c65724 100644 (file)
@@ -17,6 +17,11 @@ enum GammaCurve {
        GAMMA_REC_709 = 2,  // Same as Rec. 601.
 };
 
+enum YCbCrLumaCoefficients {
+       YCBCR_REC_601 = 0,
+       YCBCR_REC_709 = 1,
+};
+
 struct ImageFormat {
        MovitPixelFormat pixel_format;
        ColorSpace color_space;
diff --git a/input.h b/input.h
index ac03e84..8687690 100644 (file)
--- a/input.h
+++ b/input.h
@@ -24,8 +24,13 @@ public:
        // mipmap generation) at that point.
        virtual void finalize() = 0;
 
-       virtual ColorSpace get_color_space() = 0;       
-       virtual GammaCurve get_gamma_curve() = 0;       
+       // Whether this input can deliver linear gamma directly if it's
+       // asked to. (If so, set the parameter “output_linear_gamma”
+       // to activate it.)
+       virtual bool can_output_linear_gamma() const = 0;
+
+       virtual ColorSpace get_color_space() const = 0;
+       virtual GammaCurve get_gamma_curve() const = 0;
 };
 
 #endif // !defined(_INPUT_H)
diff --git a/ycbcr_input.cpp b/ycbcr_input.cpp
new file mode 100644 (file)
index 0000000..a0b9abf
--- /dev/null
@@ -0,0 +1,220 @@
+#define GL_GLEXT_PROTOTYPES 1
+
+#include <string.h>
+#include <GL/gl.h>
+#include <GL/glext.h>
+#include <assert.h>
+
+#include "ycbcr_input.h"
+#include "util.h"
+
+YCbCrInput::YCbCrInput(const ImageFormat &image_format,
+                       const YCbCrFormat &ycbcr_format,
+                       unsigned width, unsigned height)
+       : image_format(image_format),
+         ycbcr_format(ycbcr_format),
+         needs_update(false),
+         finalized(false),
+         needs_mipmaps(false),
+         width(width),
+         height(height)
+{
+       pitch[0] = pitch[1] = pitch[2] = width;
+
+       assert(width % ycbcr_format.chroma_subsampling_x == 0);
+       widths[0] = width;
+       widths[1] = width / ycbcr_format.chroma_subsampling_x;
+       widths[2] = width / ycbcr_format.chroma_subsampling_x;
+
+       assert(height % ycbcr_format.chroma_subsampling_y == 0);
+       heights[0] = height;
+       heights[1] = height / ycbcr_format.chroma_subsampling_y;
+       heights[2] = height / ycbcr_format.chroma_subsampling_y;
+
+       register_int("needs_mipmaps", &needs_mipmaps);
+}
+
+void YCbCrInput::finalize()
+{
+       // Create PBOs to hold the textures holding the input image, and then the texture itself.
+       glGenBuffers(3, pbos);
+       check_error();
+       glGenTextures(3, texture_num);
+       check_error();
+
+       for (unsigned channel = 0; channel < 3; ++channel) {
+               glBindBuffer(GL_PIXEL_UNPACK_BUFFER_ARB, pbos[channel]);
+               check_error();
+               glBufferData(GL_PIXEL_UNPACK_BUFFER_ARB, pitch[channel] * heights[channel], NULL, GL_STREAM_DRAW);
+               check_error();
+               glBindBuffer(GL_PIXEL_UNPACK_BUFFER_ARB, 0);
+               check_error();
+               
+               glBindTexture(GL_TEXTURE_2D, texture_num[channel]);
+               check_error();
+               glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
+               check_error();
+               glPixelStorei(GL_UNPACK_ROW_LENGTH, pitch[channel]);
+               check_error();
+               glTexImage2D(GL_TEXTURE_2D, 0, GL_LUMINANCE8, widths[channel], heights[channel], 0, GL_LUMINANCE, GL_UNSIGNED_BYTE, NULL);
+               check_error();
+               glPixelStorei(GL_UNPACK_ROW_LENGTH, 0);
+               check_error();
+       }
+
+       needs_update = false;
+       finalized = true;
+}
+       
+void YCbCrInput::set_gl_state(GLuint glsl_program_num, const std::string& prefix, unsigned *sampler_num)
+{
+       for (unsigned channel = 0; channel < 3; ++channel) {
+               glActiveTexture(GL_TEXTURE0 + *sampler_num + channel);
+               check_error();
+               glBindTexture(GL_TEXTURE_2D, texture_num[channel]);
+               check_error();
+
+               if (needs_update) {
+                       // Copy the pixel data into the PBO.
+                       glBindBuffer(GL_PIXEL_UNPACK_BUFFER_ARB, pbos[channel]);
+                       check_error();
+                       void *mapped_pbo = glMapBufferARB(GL_PIXEL_UNPACK_BUFFER_ARB, GL_WRITE_ONLY);
+                       memcpy(mapped_pbo, pixel_data[channel], pitch[channel] * heights[channel]);
+                       glUnmapBufferARB(GL_PIXEL_UNPACK_BUFFER_ARB);
+                       check_error();
+
+                       // Re-upload the texture from the PBO.
+                       glPixelStorei(GL_UNPACK_ROW_LENGTH, pitch[channel]);
+                       check_error();
+                       glTexSubImage2D(GL_TEXTURE_2D, 0, 0, 0, widths[channel], heights[channel], GL_LUMINANCE, GL_UNSIGNED_BYTE, BUFFER_OFFSET(0));
+                       check_error();
+                       glPixelStorei(GL_UNPACK_ROW_LENGTH, 0);
+                       check_error();
+                       glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
+                       check_error();
+                       glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
+                       check_error();
+                       glBindBuffer(GL_PIXEL_UNPACK_BUFFER_ARB, 0);
+                       check_error();
+               }
+       }
+
+       // Bind samplers.
+       set_uniform_int(glsl_program_num, prefix, "tex_y", *sampler_num + 0);
+       set_uniform_int(glsl_program_num, prefix, "tex_cb", *sampler_num + 1);
+       set_uniform_int(glsl_program_num, prefix, "tex_cr", *sampler_num + 2);
+
+       *sampler_num += 3;
+       needs_update = false;
+}
+
+std::string YCbCrInput::output_fragment_shader()
+{
+       float coeff[3], offset[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;
+       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.
+               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.
+       Matrix3x3 rgb_to_ycbcr;
+       rgb_to_ycbcr[0] = coeff[0];
+       rgb_to_ycbcr[3] = coeff[1];
+       rgb_to_ycbcr[6] = coeff[2];
+
+       float cb_fac = (224.0 / 219.0) / (coeff[0] + coeff[1] + 1.0f - coeff[2]);
+       rgb_to_ycbcr[1] = -coeff[0] * cb_fac;
+       rgb_to_ycbcr[4] = -coeff[1] * cb_fac;
+       rgb_to_ycbcr[7] = (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] = (1.0f - coeff[0]) * cr_fac;
+       rgb_to_ycbcr[5] = -coeff[1] * cr_fac;
+       rgb_to_ycbcr[8] = -coeff[2] * cr_fac;
+
+       // Inverting the matrix gives us what we need to go from YCbCr back to RGB.
+       Matrix3x3 ycbcr_to_rgb;
+       invert_3x3_matrix(rgb_to_ycbcr, ycbcr_to_rgb);
+
+       std::string frag_shader;
+
+       char buf[1024];
+       sprintf(buf,
+               "const mat3 PREFIX(inv_ycbcr_matrix) = mat3(\n"
+               "    %.8f, %.8f, %.8f,\n"
+               "    %.8f, %.8f, %.8f,\n"
+               "    %.8f, %.8f, %.8f);\n",
+               ycbcr_to_rgb[0], ycbcr_to_rgb[1], ycbcr_to_rgb[2],
+               ycbcr_to_rgb[3], ycbcr_to_rgb[4], ycbcr_to_rgb[5],
+               ycbcr_to_rgb[6], ycbcr_to_rgb[7], ycbcr_to_rgb[8]);
+       frag_shader = buf;
+
+       sprintf(buf, "const vec3 PREFIX(offset) = vec3(%.8f, %.8f, %.8f);\n",
+               offset[0], offset[1], offset[2]);
+       frag_shader += buf;
+
+       sprintf(buf, "const vec3 PREFIX(scale) = vec3(%.8f, %.8f, %.8f);\n",
+               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
+       //
+       // Obviously, the chroma plane here needs to be moved to the left,
+       // which means _adding_ 0.5 to the texture coordinates when sampling
+       // chroma.
+       float chroma_offset_x = (0.5f - ycbcr_format.chroma_x_position) / widths[1];
+       float chroma_offset_y = (0.5f - ycbcr_format.chroma_y_position) / heights[1];
+       sprintf(buf, "const vec2 PREFIX(chroma_offset) = vec2(%.8f, %.8f);\n",
+               chroma_offset_x, chroma_offset_y);
+       frag_shader += buf;
+
+       frag_shader += read_file("ycbcr_input.frag");
+       return frag_shader;
+}
diff --git a/ycbcr_input.frag b/ycbcr_input.frag
new file mode 100644 (file)
index 0000000..13e44b0
--- /dev/null
@@ -0,0 +1,23 @@
+uniform sampler2D PREFIX(tex_y);
+uniform sampler2D PREFIX(tex_cb);
+uniform sampler2D PREFIX(tex_cr);
+
+vec4 FUNCNAME(vec2 tc) {
+       // OpenGL's origin is bottom-left, but most graphics software assumes
+       // a top-left origin. Thus, for inputs that come from the user,
+       // we flip the y coordinate.
+       tc.y = 1.0 - tc.y;
+
+       vec3 ycbcr;
+       ycbcr.x = texture2D(PREFIX(tex_y), tc).x;
+       ycbcr.y = texture2D(PREFIX(tex_cb), tc + PREFIX(chroma_offset)).x;
+       ycbcr.z = texture2D(PREFIX(tex_cr), tc + PREFIX(chroma_offset)).x;
+
+       ycbcr -= PREFIX(offset);
+       ycbcr *= PREFIX(scale);
+
+       vec4 rgba;
+       rgba.rgb = PREFIX(inv_ycbcr_matrix) * ycbcr;
+       rgba.a = 1.0;
+       return rgba;
+}
diff --git a/ycbcr_input.h b/ycbcr_input.h
new file mode 100644 (file)
index 0000000..fd9db27
--- /dev/null
@@ -0,0 +1,95 @@
+#ifndef _YCBCR_INPUT_H
+#define _YCBCR_INPUT_H 1
+
+// YCbCrInput is for handling planar 8-bit Y'CbCr (also sometimes, usually rather
+// imprecisely, called “YUV”), which is typically what you get from a video decoder.
+// It upsamples planes as needed, using the default linear upsampling OpenGL gives you.
+
+#include "input.h"
+
+struct YCbCrFormat {
+       // Which formula for Y' to use.
+       YCbCrLumaCoefficients luma_coefficients;
+
+       // If true, assume Y'CbCr coefficients are full-range, ie. go from 0 to 255
+       // instead of the limited 220/225 steps in classic MPEG. For instance,
+       // JPEG uses the Rec. 601 luma coefficients, but full range.
+       bool full_range;
+
+       // Sampling factors for chroma components. For no subsampling (4:4:4),
+       // set both to 1.
+       unsigned chroma_subsampling_x, chroma_subsampling_y;
+
+       // Positioning of the chroma samples. MPEG-1 and JPEG is (0.5, 0.5);
+       // MPEG-2 and newer typically are (0.0, 0.5).
+       float chroma_x_position, chroma_y_position;
+};
+
+class YCbCrInput : public Input {
+public:
+       YCbCrInput(const ImageFormat &image_format,
+                  const YCbCrFormat &ycbcr_format,
+                  unsigned width, unsigned height);
+
+       // Create the texture itself. We cannot do this in the constructor,
+       // because we don't necessarily know all the settings (sRGB texture,
+       // mipmap generation) at that point.
+       void finalize();
+
+       virtual bool can_output_linear_gamma() const { return false; }
+
+       std::string output_fragment_shader();
+
+       // Uploads the texture if it has changed since last time.
+       void set_gl_state(GLuint glsl_program_num, const std::string& prefix, unsigned *sampler_num);
+
+       ColorSpace get_color_space() const { return image_format.color_space; }
+       GammaCurve get_gamma_curve() const { return image_format.gamma_curve; }
+
+       // Tells the input where to fetch the actual pixel data. Note that if you change
+       // this data, you must either call set_pixel_data() again (using the same pointer
+       // is fine), or invalidate_pixel_data(). Otherwise, the texture won't be re-uploaded
+       // on subsequent frames.
+       void set_pixel_data(unsigned channel, const unsigned char *pixel_data)
+       {
+               assert(channel >= 0 && channel < 3);
+               this->pixel_data[channel] = pixel_data;
+               invalidate_pixel_data();
+       }
+
+       void invalidate_pixel_data()
+       {
+               needs_update = true;
+       }
+
+       const unsigned char *get_pixel_data(unsigned channel) const
+       {
+               assert(channel >= 0 && channel < 3);
+               return pixel_data[channel];
+       }
+
+       void set_pitch(unsigned channel, unsigned pitch) {
+               assert(!finalized);
+               assert(channel >= 0 && channel < 3);
+               this->pitch[channel] = pitch;
+       }
+
+       unsigned get_pitch(unsigned channel) {
+               assert(channel >= 0 && channel < 3);
+               return pitch[channel];
+       }
+
+private:
+       ImageFormat image_format;
+       YCbCrFormat ycbcr_format;
+       GLuint pbos[3], texture_num[3];
+       bool needs_update, finalized;
+
+       int needs_mipmaps;
+
+       unsigned width, height, widths[3], heights[3];
+       const unsigned char *pixel_data[3];
+       unsigned pitch[3];
+};
+
+#endif // !defined(_YCBCR_INPUT_H)