Add a mode for YCbCrInput where Cb and Cr are in the same texture.
authorSteinar H. Gunderson <sgunderson@bigfoot.com>
Thu, 17 Sep 2015 23:48:10 +0000 (01:48 +0200)
committerSteinar H. Gunderson <sgunderson@bigfoot.com>
Thu, 17 Sep 2015 23:48:10 +0000 (01:48 +0200)
version.h
ycbcr_422interleaved_input.h
ycbcr_input.cpp
ycbcr_input.frag
ycbcr_input.h
ycbcr_input_test.cpp

index be23939..5a08560 100644 (file)
--- a/version.h
+++ b/version.h
@@ -5,6 +5,6 @@
 // changes, even within git versions. There is no specific version
 // documentation outside the regular changelogs, though.
 
-#define MOVIT_VERSION 5
+#define MOVIT_VERSION 6
 
 #endif // !defined(_MOVIT_VERSION_H)
index b7000a0..a8c7773 100644 (file)
 // RGBA texture (from which we sample chroma). We throw away half of the color
 // channels each time, so bandwidth is wasted, but it makes for a very
 // uncomplicated shader.
+//
+// Note that if you can shuffle your data around very cheaply on the CPU
+// (say, while you're decoding it out of some other buffer anyway),
+// regular YCbCrInput with YCBCR_INPUT_SPLIT_Y_AND_CBCR will probably be
+// more efficient, as it doesn't need this bandwidth waste.
 
 #include <epoxy/gl.h>
 #include <string>
index ed1f569..7f58f3f 100644 (file)
@@ -18,9 +18,11 @@ namespace movit {
 
 YCbCrInput::YCbCrInput(const ImageFormat &image_format,
                        const YCbCrFormat &ycbcr_format,
-                       unsigned width, unsigned height)
+                       unsigned width, unsigned height,
+                       YCbCrInputSplitting ycbcr_input_splitting)
        : image_format(image_format),
          ycbcr_format(ycbcr_format),
+         ycbcr_input_splitting(ycbcr_input_splitting),
          width(width),
          height(height),
          resource_pool(NULL)
@@ -41,13 +43,21 @@ YCbCrInput::YCbCrInput(const ImageFormat &image_format,
        pixel_data[0] = pixel_data[1] = pixel_data[2] = NULL;
 
        register_uniform_sampler2d("tex_y", &uniform_tex_y);
-       register_uniform_sampler2d("tex_cb", &uniform_tex_cb);
-       register_uniform_sampler2d("tex_cr", &uniform_tex_cr);
+
+       if (ycbcr_input_splitting == YCBCR_INPUT_SPLIT_Y_AND_CBCR) {
+               num_channels = 2;
+               register_uniform_sampler2d("tex_cbcr", &uniform_tex_cb);
+       } else {
+               assert(ycbcr_input_splitting == YCBCR_INPUT_PLANAR);
+               num_channels = 3;
+               register_uniform_sampler2d("tex_cb", &uniform_tex_cb);
+               register_uniform_sampler2d("tex_cr", &uniform_tex_cr);
+       }
 }
 
 YCbCrInput::~YCbCrInput()
 {
-       for (unsigned channel = 0; channel < 3; ++channel) {
+       for (unsigned channel = 0; channel < num_channels; ++channel) {
                if (texture_num[channel] != 0) {
                        resource_pool->release_2d_texture(texture_num[channel]);
                }
@@ -56,13 +66,22 @@ YCbCrInput::~YCbCrInput()
 
 void YCbCrInput::set_gl_state(GLuint glsl_program_num, const string& prefix, unsigned *sampler_num)
 {
-       for (unsigned channel = 0; channel < 3; ++channel) {
+       for (unsigned channel = 0; channel < num_channels; ++channel) {
                glActiveTexture(GL_TEXTURE0 + *sampler_num + channel);
                check_error();
 
                if (texture_num[channel] == 0) {
+                       GLenum format, internal_format;
+                       if (channel == 1 && ycbcr_input_splitting == YCBCR_INPUT_SPLIT_Y_AND_CBCR) {
+                               format = GL_RG;
+                               internal_format = GL_RG8;
+                       } else {
+                               format = GL_RED;
+                               internal_format = GL_R8;
+                       }
+
                        // (Re-)upload the texture.
-                       texture_num[channel] = resource_pool->create_2d_texture(GL_R8, widths[channel], heights[channel]);
+                       texture_num[channel] = resource_pool->create_2d_texture(internal_format, widths[channel], heights[channel]);
                        glBindTexture(GL_TEXTURE_2D, texture_num[channel]);
                        check_error();
                        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
@@ -73,7 +92,7 @@ void YCbCrInput::set_gl_state(GLuint glsl_program_num, const string& prefix, uns
                        check_error();
                        glPixelStorei(GL_UNPACK_ROW_LENGTH, pitch[channel]);
                        check_error();
-                       glTexSubImage2D(GL_TEXTURE_2D, 0, 0, 0, widths[channel], heights[channel], GL_RED, GL_UNSIGNED_BYTE, pixel_data[channel]);
+                       glTexSubImage2D(GL_TEXTURE_2D, 0, 0, 0, widths[channel], heights[channel], format, GL_UNSIGNED_BYTE, pixel_data[channel]);
                        check_error();
                        glPixelStorei(GL_UNPACK_ROW_LENGTH, 0);
                        check_error();
@@ -93,9 +112,11 @@ void YCbCrInput::set_gl_state(GLuint glsl_program_num, const string& prefix, uns
        // Bind samplers.
        uniform_tex_y = *sampler_num + 0;
        uniform_tex_cb = *sampler_num + 1;
-       uniform_tex_cr = *sampler_num + 2;
+       if (ycbcr_input_splitting == YCBCR_INPUT_PLANAR) {
+               uniform_tex_cr = *sampler_num + 2;
+       }
 
-       *sampler_num += 3;
+       *sampler_num += num_channels;
 }
 
 string YCbCrInput::output_fragment_shader()
@@ -121,6 +142,15 @@ string YCbCrInput::output_fragment_shader()
                ycbcr_format.cr_y_position, ycbcr_format.chroma_subsampling_y, heights[2]);
        frag_shader += output_glsl_vec2("PREFIX(cr_offset)", cr_offset_x, cr_offset_y);
 
+       if (ycbcr_input_splitting == YCBCR_INPUT_SPLIT_Y_AND_CBCR) {
+               char buf[256];
+               snprintf(buf, sizeof(buf), "#define CB_CR_SAME_TEXTURE 1\n#define CB_CR_OFFSETS_EQUAL %d\n",
+                       (fabs(ycbcr_format.cb_x_position - ycbcr_format.cr_x_position) < 1e-6));
+               frag_shader += buf;
+       } else {
+               frag_shader += "#define CB_CR_SAME_TEXTURE 0\n";
+       }
+
        frag_shader += read_file("ycbcr_input.frag");
        return frag_shader;
 }
index b84499d..c57c6d1 100644 (file)
@@ -1,7 +1,8 @@
 // Implicit uniforms:
 // uniform sampler2D PREFIX(tex_y);
-// uniform sampler2D PREFIX(tex_cb);
-// uniform sampler2D PREFIX(tex_cr);
+// uniform sampler2D PREFIX(tex_cbcr);  // If CB_CR_SAME_TEXTURE.
+// uniform sampler2D PREFIX(tex_cb);    // If not CB_CR_SAME_TEXTURE.
+// uniform sampler2D PREFIX(tex_cr);    // If not CB_CR_SAME_TEXTURE.
 
 vec4 FUNCNAME(vec2 tc) {
        // OpenGL's origin is bottom-left, but most graphics software assumes
@@ -11,8 +12,17 @@ vec4 FUNCNAME(vec2 tc) {
 
        vec3 ycbcr;
        ycbcr.x = tex2D(PREFIX(tex_y), tc).x;
+#if CB_CR_SAME_TEXTURE
+#if CB_CR_OFFSETS_EQUAL
+       ycbcr.yz = tex2D(PREFIX(tex_cbcr), tc + PREFIX(cb_offset)).xy;
+#else
+       ycbcr.y = tex2D(PREFIX(tex_cbcr), tc + PREFIX(cb_offset)).x;
+       ycbcr.z = tex2D(PREFIX(tex_cbcr), tc + PREFIX(cr_offset)).x;
+#endif
+#else
        ycbcr.y = tex2D(PREFIX(tex_cb), tc + PREFIX(cb_offset)).x;
        ycbcr.z = tex2D(PREFIX(tex_cr), tc + PREFIX(cr_offset)).x;
+#endif
 
        ycbcr -= PREFIX(offset);
 
index 7db5375..282b55a 100644 (file)
@@ -19,11 +19,28 @@ namespace movit {
 
 class ResourcePool;
 
+// Whether the data is fully planar (Y', Cb and Cr in one texture each)
+// or not. Note that this input does currently not support fully interleaved
+// data (Y', Cb and Cr next to each other), as 4:4:4 interleaved Y'CbCr seems
+// to be rare; however, YCbCr422InterleavedInput supports the important special
+// case of 4:2:2 interleaved.
+enum YCbCrInputSplitting {
+       // The standard, default case; Y', Cb and Cr in one texture each.
+       YCBCR_INPUT_PLANAR,
+
+       // Y' in one texture, and then Cb and Cr interleaved in one texture.
+       // In particular, this is a superset of the relatively popular NV12 mode.
+       // If you specify this mode, the “Cr” pointer texture will be unused
+       // (the ”Cb” texture contains both).
+       YCBCR_INPUT_SPLIT_Y_AND_CBCR,
+};
+
 class YCbCrInput : public Input {
 public:
        YCbCrInput(const ImageFormat &image_format,
                   const YCbCrFormat &ycbcr_format,
-                  unsigned width, unsigned height);
+                  unsigned width, unsigned height,
+                  YCbCrInputSplitting ycbcr_input_splitting = YCBCR_INPUT_PLANAR);
        ~YCbCrInput();
 
        virtual std::string effect_type_id() const { return "YCbCrInput"; }
@@ -54,7 +71,7 @@ public:
        // the pointer (and PBO, if set) has to be valid at the time of the render call.
        void set_pixel_data(unsigned channel, const unsigned char *pixel_data, GLuint pbo = 0)
        {
-               assert(channel >= 0 && channel < 3);
+               assert(channel >= 0 && channel < num_channels);
                this->pixel_data[channel] = pixel_data;
                this->pbos[channel] = pbo;
                invalidate_pixel_data();
@@ -63,7 +80,7 @@ public:
        void invalidate_pixel_data();
 
        void set_pitch(unsigned channel, unsigned pitch) {
-               assert(channel >= 0 && channel < 3);
+               assert(channel >= 0 && channel < num_channels);
                this->pitch[channel] = pitch;
                invalidate_pixel_data();
        }
@@ -78,6 +95,8 @@ public:
 private:
        ImageFormat image_format;
        YCbCrFormat ycbcr_format;
+       GLuint num_channels;
+       YCbCrInputSplitting ycbcr_input_splitting;
        GLuint pbos[3], texture_num[3];
        GLint uniform_tex_y, uniform_tex_cb, uniform_tex_cr;
 
index 873a6c5..8b69e87 100644 (file)
@@ -484,4 +484,58 @@ TEST(YCbCrInputTest, PBO) {
        glDeleteBuffers(1, &pbo);
 }
 
+TEST(YCbCrInputTest, CombinedCbAndCr) {
+       const int width = 1;
+       const int height = 5;
+
+       // Pure-color test inputs, calculated with the formulas in Rec. 601
+       // section 2.5.4.
+       unsigned char y[width * height] = {
+               16, 235, 81, 145, 41,
+       };
+       unsigned char cb_cr[width * height * 2] = {
+               128, 128,
+               128, 128,
+                90, 240,
+                54,  34,
+               240, 110,
+       };
+       float expected_data[4 * width * height] = {
+               0.0, 0.0, 0.0, 1.0,
+               1.0, 1.0, 1.0, 1.0,
+               1.0, 0.0, 0.0, 1.0,
+               0.0, 1.0, 0.0, 1.0,
+               0.0, 0.0, 1.0, 1.0,
+       };
+       float out_data[4 * width * height];
+
+       EffectChainTester tester(NULL, width, height);
+
+       ImageFormat format;
+       format.color_space = COLORSPACE_sRGB;
+       format.gamma_curve = GAMMA_sRGB;
+
+       YCbCrFormat ycbcr_format;
+       ycbcr_format.luma_coefficients = YCBCR_REC_601;
+       ycbcr_format.full_range = false;
+       ycbcr_format.num_levels = 256;
+       ycbcr_format.chroma_subsampling_x = 1;
+       ycbcr_format.chroma_subsampling_y = 1;
+       ycbcr_format.cb_x_position = 0.5f;
+       ycbcr_format.cb_y_position = 0.5f;
+       ycbcr_format.cr_x_position = 0.5f;
+       ycbcr_format.cr_y_position = 0.5f;
+
+       YCbCrInput *input = new YCbCrInput(format, ycbcr_format, width, height, YCBCR_INPUT_SPLIT_Y_AND_CBCR);
+       input->set_pixel_data(0, y);
+       input->set_pixel_data(1, cb_cr);
+       tester.get_chain()->add_input(input);
+
+       tester.run(out_data, GL_RGBA, COLORSPACE_sRGB, GAMMA_sRGB);
+
+       // Y'CbCr isn't 100% accurate (the input values are rounded),
+       // so we need some leeway.
+       expect_equal(expected_data, out_data, 4 * width, height, 0.025, 0.002);
+}
+
 }  // namespace movit