Stop using BGR, BGRA and grayscale formats.

[movit] / fft_pass_effect.cpp

diff --git a/fft_pass_effect.cpp b/fft_pass_effect.cpp
index 695a763f0b14f79cd119e527737ff8c4a382e7bc..ee0b983ae92002875d5b8e86538e21b09846991b 100644 (file)
--- a/fft_pass_effect.cpp
+++ b/fft_pass_effect.cpp
@@ -1,7 +1,9 @@
 #include <epoxy/gl.h>
 #include <math.h>
 
+#include "effect_chain.h"
 #include "effect_util.h"
+#include "fp16.h"
 #include "fft_pass_effect.h"
 #include "util.h"
 
@@ -39,15 +41,13 @@ void FFTPassEffect::set_gl_state(GLuint glsl_program_num, const string &prefix,
 
        int input_size = (direction == VERTICAL) ? input_height : input_width;
 
-       // See the comments on changes_output_size() in the .h file to see
-       // why this is legal. It is _needed_ because it counteracts the
-       // precision issues we get because we sample the input texture with
-       // normalized coordinates (especially when the repeat count along
-       // the axis is not a power of two); we very rapidly end up in narrowly
-       // missing a texel center, which causes precision loss to propagate
-       // throughout the FFT.
-       assert(*sampler_num == 1);
-       glActiveTexture(GL_TEXTURE0);
+       // This is needed because it counteracts the precision issues we get
+       // because we sample the input texture with normalized coordinates
+       // (especially when the repeat count along the axis is not a power of
+       // two); we very rapidly end up in narrowly missing a texel center,
+       // which causes precision loss to propagate throughout the FFT.
+       Node *self = chain->find_node_for_effect(this);
+       glActiveTexture(chain->get_input_sampler(self, 0));
        check_error();
        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
        check_error();
@@ -79,7 +79,7 @@ void FFTPassEffect::set_gl_state(GLuint glsl_program_num, const string &prefix,
        // bit, so the stride is 8, and so on.
 
        assert((fft_size & (fft_size - 1)) == 0);  // Must be power of two.
-       float *tmp = new float[fft_size * 4];
+       fp16_int_t *tmp = new fp16_int_t[fft_size * 4];
        int subfft_size = 1 << pass_number;
        double mulfac;
        if (inverse) {
@@ -117,17 +117,19 @@ void FFTPassEffect::set_gl_state(GLuint glsl_program_num, const string &prefix,
                // is that we can have multiple FFTs along the same line,
                // and want to reuse the support texture by repeating it.
                int base = k * stride * 2 + offset;
-               int support_texture_index;
+               int support_texture_index = i;
+               int src1 = base;
+               int src2 = base + stride;
                if (direction == FFTPassEffect::VERTICAL) {
                        // Compensate for OpenGL's bottom-left convention.
-                       support_texture_index = fft_size - i - 1;
-               } else {
-                       support_texture_index = i;
+                       support_texture_index = fft_size - support_texture_index - 1;
+                       src1 = fft_size - src1 - 1;
+                       src2 = fft_size - src2 - 1;
                }
-               tmp[support_texture_index * 4 + 0] = (base - support_texture_index) / double(input_size);
-               tmp[support_texture_index * 4 + 1] = (base + stride - support_texture_index) / double(input_size);
-               tmp[support_texture_index * 4 + 2] = twiddle_real;
-               tmp[support_texture_index * 4 + 3] = twiddle_imag;
+               tmp[support_texture_index * 4 + 0] = fp64_to_fp16((src1 - support_texture_index) / double(input_size));
+               tmp[support_texture_index * 4 + 1] = fp64_to_fp16((src2 - support_texture_index) / double(input_size));
+               tmp[support_texture_index * 4 + 2] = fp64_to_fp16(twiddle_real);
+               tmp[support_texture_index * 4 + 3] = fp64_to_fp16(twiddle_imag);
        }
 
        glActiveTexture(GL_TEXTURE0 + *sampler_num);
@@ -143,11 +145,14 @@ void FFTPassEffect::set_gl_state(GLuint glsl_program_num, const string &prefix,
 
        // Supposedly FFTs are very sensitive to inaccuracies in the twiddle factors,
        // at least according to a paper by Schatzman (see gpuwave.pdf reference [30]
-       // for the full reference), so we keep them at 32-bit. However, for
-       // small sizes, all components are exact anyway, so we can cheat there
-       // (although noting that the source coordinates become somewhat less
-       // accurate then, too).
-       glTexImage2D(GL_TEXTURE_2D, 0, (subfft_size <= 4) ? GL_RGBA16F : GL_RGBA32F, fft_size, 1, 0, GL_RGBA, GL_FLOAT, tmp);
+       // for the full reference); however, practical testing indicates that it's
+       // not a problem to keep the twiddle factors at 16-bit, at least as long as
+       // we round them properly--it would seem that Schatzman were mainly talking
+       // about poor sin()/cos() approximations. Thus, we store them in 16-bit,
+       // which gives a nice speed boost.
+       //
+       // Note that the source coordinates become somewhat less accurate too, though.
+       glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA16F, fft_size, 1, 0, GL_RGBA, GL_HALF_FLOAT, tmp);
        check_error();
 
        delete[] tmp;