Add a deinterlacer based on YADIF.

[movit] / deinterlace_effect.cpp

diff --git a/deinterlace_effect.cpp b/deinterlace_effect.cpp
new file mode 100644 (file)
index 0000000..8d9a96c
--- /dev/null
+++ b/deinterlace_effect.cpp
@@ -0,0 +1,128 @@
+#include <epoxy/gl.h>
+
+#include "deinterlace_effect.h"
+#include "util.h"
+
+using namespace std;
+
+namespace movit {
+
+DeinterlaceEffect::DeinterlaceEffect()
+       : enable_spatial_interlacing_check(true),
+         current_field_position(TOP),
+         num_lines(1080)
+{
+       register_int("enable_spatial_interlacing_check", (int *)&enable_spatial_interlacing_check);
+       register_int("current_field_position", (int *)&current_field_position);
+       register_uniform_float("num_lines", &num_lines);
+       register_uniform_float("inv_width", &inv_width);
+       register_uniform_float("self_offset", &self_offset);
+       register_uniform_float_array("current_offset", current_offset, 2);
+       register_uniform_float_array("other_offset", other_offset, 3);
+}
+
+string DeinterlaceEffect::output_fragment_shader()
+{
+       char buf[256];
+       snprintf(buf, sizeof(buf), "#define YADIF_ENABLE_SPATIAL_INTERLACING_CHECK %d\n",
+               enable_spatial_interlacing_check);
+       string frag_shader = buf;
+
+       frag_shader += read_file("deinterlace_effect.frag");
+       return frag_shader;
+}
+
+void DeinterlaceEffect::inform_input_size(unsigned input_num, unsigned width, unsigned height)
+{
+       assert(input_num >= 0 && input_num < 5);
+       widths[input_num] = width;
+       heights[input_num] = height;
+       num_lines = height * 2;
+}
+
+void DeinterlaceEffect::get_output_size(unsigned *width, unsigned *height,
+                                        unsigned *virtual_width, unsigned *virtual_height) const
+{
+       assert(widths[0] == widths[1]);
+       assert(widths[1] == widths[2]);
+       assert(widths[2] == widths[3]);
+       assert(widths[3] == widths[4]);
+       assert(heights[0] == heights[1]);
+       assert(heights[1] == heights[2]);
+       assert(heights[2] == heights[3]);
+       assert(heights[3] == heights[4]);
+       *width = *virtual_width = widths[0];
+       *height = *virtual_height = heights[0] * 2;
+}
+
+void DeinterlaceEffect::set_gl_state(GLuint glsl_program_num, const string &prefix, unsigned *sampler_num)
+{
+       Effect::set_gl_state(glsl_program_num, prefix, sampler_num);
+
+       inv_width = 1.0 / widths[0];
+
+       // Texel centers: t = output texel center for top field, b = for bottom field,
+       // x = the input texel. (The same area is two pixels for output, one for input;
+       // thus the stippled line in the middle.)
+       //
+       // +---------+
+       // |         |
+       // |    t    |
+       // |         |
+       // | - -x- - |
+       // |         |
+       // |    b    |
+       // |         |
+       // +---------+
+       //
+       // Note as usual OpenGL's bottom-left convention.
+       if (current_field_position == 0) {
+               // Top.
+               self_offset = -0.5 / num_lines;
+       } else {
+               // Bottom.
+               assert(current_field_position == 1);
+               self_offset = 0.5 / num_lines;
+       }
+
+       // Having now established where the texels lie for the uninterpolated samples,
+       // we can use that to figure out where to sample for the interpolation. Drawing
+       // the fields as what lines they represent, here for three-pixel high fields
+       // with current_field_position == 0 (plus an “o” to mark the pixel we're trying
+       // to interpolate, and “c” for corresponding texel in the other field):
+       //
+       // Prev Cur Next
+       //       x
+       //   x       x
+       //       x
+       //   c   o   c
+       //       x
+       //   x       x
+       //
+       // Obviously, for sampling in the current field, we are one half-texel off
+       // compared to <self_offset>, so sampling in the current field is easy:
+       current_offset[0] = self_offset - 0.5 / heights[0];
+       current_offset[1] = self_offset + 0.5 / heights[0];
+
+       // Now to find the texel in the other fields corresponding to the pixel
+       // we're trying to interpolate, let's realign the diagram above:
+       //
+       // Prev Cur Next
+       //   x   x   x
+       //
+       //   c   x   c
+       //       o
+       //   x   x   x
+       //
+       // So obviously for this case, we need to center on the same place as
+       // current_offset[1] (the texel directly above the o; note again the
+       // bottom-left convention). For the case of current_field_position == 1,
+       // the shift in the alignment goes the other way, and what we want
+       // is current_offset[0] (the texel directly below the o).
+       float center_offset = current_offset[1 - current_field_position];
+       other_offset[0] = center_offset - 1.0 / heights[0];
+       other_offset[1] = center_offset;
+       other_offset[2] = center_offset + 1.0 / heights[0];
+}
+
+}  // namespace movit