Do our own fp16 conversion in ResampleEffect.

[movit] / resample_effect.cpp

diff --git a/resample_effect.cpp b/resample_effect.cpp
index 6c490f141bc1a87b9f86db44b90b5d64f75d0dd7..4af60de7d3c47c6089a560f0d23c2ce62594cd81 100644 (file)
--- a/resample_effect.cpp
+++ b/resample_effect.cpp
@@ -10,11 +10,14 @@
 
 #include "effect_chain.h"
 #include "effect_util.h"
+#include "fp16.h"
 #include "resample_effect.h"
 #include "util.h"
 
 using namespace std;
 
+namespace movit {
+
 namespace {
 
 float sinc(float x)
@@ -140,7 +143,7 @@ void ResampleEffect::inform_input_size(unsigned input_num, unsigned width, unsig
        input_height = height;
        update_size();
 }
-               
+
 void ResampleEffect::update_size()
 {
        bool ok = true;
@@ -229,7 +232,6 @@ void SingleResamplePassEffect::update_texture(GLuint glsl_program_num, const str
                assert(false);
        }
 
-
        // For many resamplings (e.g. 640 -> 1280), we will end up with the same
        // set of samples over and over again in a loop. Thus, we can compute only
        // the first such loop, and then ask the card to repeat the texture for us.
@@ -305,6 +307,7 @@ void SingleResamplePassEffect::update_texture(GLuint glsl_program_num, const str
                        weights[(y * src_samples + i) * 2 + 0] = weight * radius_scaling_factor;
                        weights[(y * src_samples + i) * 2 + 1] = (src_y + 0.5) / float(src_size);
                }
+
        }
 
        // Now make use of the bilinear filtering in the GPU to reduce the number of samples
@@ -323,14 +326,36 @@ void SingleResamplePassEffect::update_texture(GLuint glsl_program_num, const str
 
        // Now that we know the right width, actually combine the samples.
        float *bilinear_weights = new float[dst_samples * src_bilinear_samples * 2];
+       fp16_int_t *bilinear_weights_fp16 = new fp16_int_t[dst_samples * src_bilinear_samples * 2];
        for (unsigned y = 0; y < dst_samples; ++y) {
+               float *bilinear_weights_ptr = bilinear_weights + (y * src_bilinear_samples) * 2;
+               fp16_int_t *bilinear_weights_fp16_ptr = bilinear_weights_fp16 + (y * src_bilinear_samples) * 2;
                unsigned num_samples_saved = combine_samples(
                        weights + (y * src_samples) * 2,
-                       bilinear_weights + (y * src_bilinear_samples) * 2,
+                       bilinear_weights_ptr,
                        src_samples,
                        src_samples - src_bilinear_samples);
                assert(int(src_samples) - int(num_samples_saved) == src_bilinear_samples);
-       }       
+
+               // Convert to fp16.
+               for (int i = 0; i < src_bilinear_samples; ++i) {
+                       bilinear_weights_fp16_ptr[i * 2 + 0] = fp64_to_fp16(bilinear_weights_ptr[i * 2 + 0]);
+                       bilinear_weights_fp16_ptr[i * 2 + 1] = fp64_to_fp16(bilinear_weights_ptr[i * 2 + 1]);
+               }
+
+               // Normalize so that the sum becomes one. Note that we do it twice;
+               // this sometimes helps a tiny little bit when we have many samples.
+               for (int normalize_pass = 0; normalize_pass < 2; ++normalize_pass) {
+                       double sum = 0.0;
+                       for (int i = 0; i < src_bilinear_samples; ++i) {
+                               sum += fp16_to_fp64(bilinear_weights_fp16_ptr[i * 2 + 0]);
+                       }
+                       for (int i = 0; i < src_bilinear_samples; ++i) {
+                               bilinear_weights_fp16_ptr[i * 2 + 0] = fp64_to_fp16(
+                                       fp16_to_fp64(bilinear_weights_fp16_ptr[i * 2 + 0]) / sum);
+                       }
+               }
+       }
 
        // Encode as a two-component texture. Note the GL_REPEAT.
        glActiveTexture(GL_TEXTURE0 + *sampler_num);
@@ -343,11 +368,12 @@ void SingleResamplePassEffect::update_texture(GLuint glsl_program_num, const str
        check_error();
        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT);
        check_error();
-       glTexImage2D(GL_TEXTURE_2D, 0, GL_RG16F, src_bilinear_samples, dst_samples, 0, GL_RG, GL_FLOAT, bilinear_weights);
+       glTexImage2D(GL_TEXTURE_2D, 0, GL_RG16F, src_bilinear_samples, dst_samples, 0, GL_RG, GL_HALF_FLOAT, bilinear_weights_fp16);
        check_error();
 
        delete[] weights;
        delete[] bilinear_weights;
+       delete[] bilinear_weights_fp16;
 }
 
 void SingleResamplePassEffect::set_gl_state(GLuint glsl_program_num, const string &prefix, unsigned *sampler_num)
@@ -392,3 +418,5 @@ void SingleResamplePassEffect::set_gl_state(GLuint glsl_program_num, const strin
        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
        check_error();
 }
+
+}  // namespace movit