--- /dev/null
+/*
+ * transition_vqm.c -- video quality measurement
+ * Copyright (c) 2012 Dan Dennedy <dan@dennedy.org>
+ * Core psnr and ssim routines based on code from
+ * qsnr (C) 2010 E. Oriani, ema <AT> fastwebnet <DOT> it
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program. If not, see <http://www.gnu.org/licenses/>
+ */
+
+#include <framework/mlt.h>
+#include <string.h>
+#include <math.h>
+#include <stdio.h>
+
+static double calc_psnr( const uint8_t *a, const uint8_t *b, int size, int bpp )
+{
+ double mse = 0.0;
+ int n = size + 1;
+
+ while ( --n )
+ {
+ int diff = *a - *b;
+ mse += diff * diff;
+ a += bpp;
+ b += bpp;
+ }
+
+ return 10.0 * log10( 255.0 * 255.0 / ( mse == 0 ? 1e-10 : mse/size ) );
+}
+
+static double calc_ssim( const uint8_t *a, const uint8_t *b, int width, int height, int window_size, int bpp )
+{
+ int windows_x = width / window_size;
+ int windows_y = height / window_size;
+ double avg = 0.0;
+
+ if ( !windows_x || !windows_y )
+ return 0.0;
+
+ // for each window
+ for ( int y = 0; y < windows_y; ++y )
+ for ( int x = 0; x < windows_x; ++x )
+ {
+ int base_offset = x * window_size + y * window_size * width;
+ double ref_acc = 0.0,
+ ref_acc_2 = 0.0,
+ cmp_acc = 0.0,
+ cmp_acc_2 = 0.0,
+ ref_cmp_acc = 0.0;
+
+ // accumulate the pixel values for this window
+ for ( int j = 0; j < window_size; ++j )
+ for ( int i = 0; i < window_size; ++i )
+ {
+ uint8_t c_a = a[bpp * (base_offset + j * width + i)];
+ uint8_t c_b = b[bpp * (base_offset + j * width + i)];
+ ref_acc += c_a;
+ ref_acc_2 += c_a * c_a;
+ cmp_acc += c_b;
+ cmp_acc_2 += c_b * c_b;
+ ref_cmp_acc += c_a * c_b;
+ }
+
+ // compute the SSIM for this window
+ // http://en.wikipedia.org/wiki/SSIM
+ // http://en.wikipedia.org/wiki/Variance
+ // http://en.wikipedia.org/wiki/Covariance
+ double n_samples = window_size * window_size,
+ ref_avg = ref_acc / n_samples,
+ ref_var = ref_acc_2 / n_samples - ref_avg * ref_avg,
+ cmp_avg = cmp_acc / n_samples,
+ cmp_var = cmp_acc_2 / n_samples - cmp_avg * cmp_avg,
+ ref_cmp_cov = ref_cmp_acc / n_samples - ref_avg * cmp_avg,
+ c1 = 6.5025, // (0.01*255.0)^2
+ c2 = 58.5225, // (0.03*255)^2
+ ssim_num = (2.0 * ref_avg * cmp_avg + c1) * (2.0 * ref_cmp_cov + c2),
+ ssim_den = (ref_avg * ref_avg + cmp_avg * cmp_avg + c1) * (ref_var + cmp_var + c2);
+
+ // accumulate the SSIM
+ avg += ssim_num / ssim_den;
+ }
+
+ // return the average SSIM
+ return avg / windows_x / windows_y;
+}
+
+static int get_image( mlt_frame a_frame, uint8_t **image, mlt_image_format *format, int *width, int *height, int writable )
+{
+ mlt_frame b_frame = mlt_frame_pop_frame( a_frame );
+ mlt_transition transition = MLT_TRANSITION( mlt_frame_pop_service( a_frame ) );
+ uint8_t *b_image;
+ int window_size = mlt_properties_get_int( MLT_TRANSITION_PROPERTIES( transition ), "window_size" );
+ double psnr[3], ssim[3];
+
+ *format = mlt_image_yuv422;
+ mlt_frame_get_image( b_frame, &b_image, format, width, height, writable );
+ mlt_frame_get_image( a_frame, image, format, width, height, writable );
+
+ psnr[0] = calc_psnr( *image, b_image, *width * *height, 2 );
+ psnr[1] = calc_psnr( *image + 1, b_image + 1, *width * *height / 2, 4 );
+ psnr[2] = calc_psnr( *image + 3, b_image + 3, *width * *height / 2, 4 );
+ ssim[0] = calc_ssim( *image, b_image, *width, *height, window_size, 2 );
+ ssim[1] = calc_ssim( *image + 1, b_image + 1, *width / 2, *height, window_size, 4 );
+ ssim[2] = calc_ssim( *image + 3, b_image + 3, *width / 2, *height, window_size, 4 );
+ printf( "%05d %05.2f %05.2f %05.2f %5.3f %5.3f %5.3f\n",
+ mlt_frame_get_position( a_frame ), psnr[0], psnr[1], psnr[2],
+ ssim[0], ssim[1], ssim[2] );
+
+ window_size = mlt_image_format_size( *format, *width, *height, NULL ) / 2;
+ memcpy( *image + window_size, b_image + window_size, window_size );
+
+ return 0;
+}
+
+static mlt_frame process( mlt_transition transition, mlt_frame a_frame, mlt_frame b_frame )
+{
+ mlt_frame_push_service( a_frame, transition );
+ mlt_frame_push_frame( a_frame, b_frame );
+ mlt_frame_push_get_image( a_frame, get_image );
+
+ return a_frame;
+}
+
+extern "C" {
+
+mlt_transition transition_vqm_init( mlt_profile profile, mlt_service_type type, const char *id, void *arg )
+{
+ mlt_transition transition = mlt_transition_new();
+
+ if ( transition )
+ {
+ mlt_properties properties = MLT_TRANSITION_PROPERTIES( transition );
+
+ transition->process = process;
+ mlt_properties_set_int( properties, "_transition_type", 1 ); // video only
+ mlt_properties_set_int( properties, "window_size", 8 );
+ printf( "frame psnr[Y] psnr[Cb] psnr[Cr] ssim[Y] ssim[Cb] ssim[Cr]\n" );
+ }
+
+ return transition;
+}
+
+} // extern "C"
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