+/** Scale 16bit greyscale luma map using nearest neighbor.
+*/
+
+static inline void
+scale_luma ( uint16_t *dest_buf, int dest_width, int dest_height, const uint16_t *src_buf, int src_width, int src_height )
+{
+ register int i, j;
+ register int x_step = ( src_width << 16 ) / dest_width;
+ register int y_step = ( src_height << 16 ) / dest_height;
+ register int x, y = 0;
+
+ for ( i = 0; i < dest_height; i++ )
+ {
+ const uint16_t *src = src_buf + ( y >> 16 ) * src_width;
+ x = 0;
+
+ for ( j = 0; j < dest_width; j++ )
+ {
+ *dest_buf++ = src[ x >> 16 ];
+ x += x_step;
+ }
+ y += y_step;
+ }
+}
+
+static uint16_t* get_luma( mlt_properties properties, int width, int height )
+{
+ // The cached luma map information
+ int luma_width = mlt_properties_get_int( properties, "_luma.width" );
+ int luma_height = mlt_properties_get_int( properties, "_luma.height" );
+ uint16_t *luma_bitmap = mlt_properties_get_data( properties, "_luma.bitmap", NULL );
+
+ // If the filename property changed, reload the map
+ char *resource = mlt_properties_get( properties, "luma" );
+
+ if ( resource != NULL && ( luma_bitmap == NULL || luma_width != width || luma_height != height ) )
+ {
+ uint16_t *orig_bitmap = mlt_properties_get_data( properties, "_luma.orig_bitmap", NULL );
+ luma_width = mlt_properties_get_int( properties, "_luma.orig_width" );
+ luma_height = mlt_properties_get_int( properties, "_luma.orig_height" );
+
+ // Load the original luma once
+ if ( orig_bitmap == NULL )
+ {
+ char *extension = extension = strrchr( resource, '.' );
+
+ // See if it is a PGM
+ if ( extension != NULL && strcmp( extension, ".pgm" ) == 0 )
+ {
+ // Open PGM
+ FILE *f = fopen( resource, "r" );
+ if ( f != NULL )
+ {
+ // Load from PGM
+ luma_read_pgm( f, &orig_bitmap, &luma_width, &luma_height );
+ fclose( f );
+
+ // Remember the original size for subsequent scaling
+ mlt_properties_set_data( properties, "_luma.orig_bitmap", orig_bitmap, luma_width * luma_height * 2, mlt_pool_release, NULL );
+ mlt_properties_set_int( properties, "_luma.orig_width", luma_width );
+ mlt_properties_set_int( properties, "_luma.orig_height", luma_height );
+ }
+ }
+ else
+ {
+ // Get the factory producer service
+ char *factory = mlt_properties_get( properties, "factory" );
+
+ // Create the producer
+ mlt_producer producer = mlt_factory_producer( factory, resource );
+
+ // If we have one
+ if ( producer != NULL )
+ {
+ // Get the producer properties
+ mlt_properties producer_properties = mlt_producer_properties( producer );
+
+ // Ensure that we loop
+ mlt_properties_set( producer_properties, "eof", "loop" );
+
+ // Now pass all producer. properties on the transition down
+ mlt_properties_pass( producer_properties, properties, "luma." );
+
+ // We will get the alpha frame from the producer
+ mlt_frame luma_frame = NULL;
+
+ // Get the luma frame
+ if ( mlt_service_get_frame( mlt_producer_service( producer ), &luma_frame, 0 ) == 0 )
+ {
+ uint8_t *luma_image;
+ mlt_image_format luma_format = mlt_image_yuv422;
+
+ // Get image from the luma producer
+ mlt_properties_set( mlt_frame_properties( luma_frame ), "rescale.interp", "none" );
+ mlt_frame_get_image( luma_frame, &luma_image, &luma_format, &luma_width, &luma_height, 0 );
+
+ // Generate the luma map
+ if ( luma_image != NULL && luma_format == mlt_image_yuv422 )
+ luma_read_yuv422( luma_image, &orig_bitmap, luma_width, luma_height );
+
+ // Remember the original size for subsequent scaling
+ mlt_properties_set_data( properties, "_luma.orig_bitmap", orig_bitmap, luma_width * luma_height * 2, mlt_pool_release, NULL );
+ mlt_properties_set_int( properties, "_luma.orig_width", luma_width );
+ mlt_properties_set_int( properties, "_luma.orig_height", luma_height );
+
+ // Cleanup the luma frame
+ mlt_frame_close( luma_frame );
+ }
+
+ // Cleanup the luma producer
+ mlt_producer_close( producer );
+ }
+ }
+ }
+ // Scale luma map
+ luma_bitmap = mlt_pool_alloc( width * height * sizeof( uint16_t ) );
+ scale_luma( luma_bitmap, width, height, orig_bitmap, luma_width, luma_height );
+
+ // Remember the scaled luma size to prevent unnecessary scaling
+ mlt_properties_set_int( properties, "_luma.width", width );
+ mlt_properties_set_int( properties, "_luma.height", height );
+ mlt_properties_set_data( properties, "_luma.bitmap", luma_bitmap, width * height * 2, mlt_pool_release, NULL );
+ }
+ return luma_bitmap;
+}
+