added mono audio filter

[melted] / src / modules / core / filter_mono.c

diff --git a/src/modules/core/filter_mono.c b/src/modules/core/filter_mono.c
new file mode 100644 (file)
index 0000000..b11fd1f
--- /dev/null
+++ b/src/modules/core/filter_mono.c
@@ -0,0 +1,95 @@
+/*
+ * filter_mono.c -- mix all channels to a mono signal across n channels
+ * Copyright (C) 2003-2006 Ushodaya Enterprises Limited
+ * Author: Dan Dennedy <dan@dennedy.org>
+ *
+ * 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 2 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, write to the Free Software Foundation,
+ * Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
+ */
+
+#include "filter_mono.h"
+
+#include <framework/mlt_frame.h>
+
+#include <stdio.h>
+#include <stdlib.h>
+
+/** Get the audio.
+*/
+
+static int filter_get_audio( mlt_frame frame, int16_t **buffer, mlt_audio_format *format, int *frequency, int *channels, int *samples )
+{
+       // Get the properties of the a frame
+       mlt_properties properties = MLT_FRAME_PROPERTIES( frame );
+       int channels_out = mlt_properties_get_int( properties, "mono.channels" );
+       int i, j, size;
+       int16_t *new_buffer;
+
+       // Get the producer's audio
+       mlt_frame_get_audio( frame, buffer, format, frequency, channels, samples );
+
+       size = *samples * channels_out * sizeof( int16_t );
+       new_buffer = mlt_pool_alloc( size );
+       mlt_properties_set_data( properties, "audio", new_buffer, size, ( mlt_destructor )mlt_pool_release, NULL );
+
+       // Mix
+       for ( i = 0; i < *samples; i++ )
+       {
+               int16_t mixdown = 0;
+               for ( j = 0; j < *channels; j++ )
+                       mixdown += (*buffer)[ ( i * *channels ) + j ] / *channels;
+               for ( j = 0; j < channels_out; j++ )
+                       new_buffer[ ( i * channels_out ) + j ] = mixdown;
+       }
+
+       // Apply results
+       *buffer = new_buffer;
+       *channels = channels_out;
+       
+       return 0;
+}
+
+/** Filter processing.
+*/
+
+static mlt_frame filter_process( mlt_filter this, mlt_frame frame )
+{
+       mlt_properties properties = MLT_FILTER_PROPERTIES( this );
+       mlt_properties frame_props = MLT_FRAME_PROPERTIES( frame );
+
+       // Propogate the parameters
+       mlt_properties_set_int( frame_props, "mono.channels", mlt_properties_get_int( properties, "channels" ) );
+
+       // Override the get_audio method
+       mlt_frame_push_audio( frame, filter_get_audio );
+
+       return frame;
+}
+
+/** Constructor for the filter.
+*/
+
+mlt_filter filter_mono_init( char *arg )
+{
+       mlt_filter this = mlt_filter_new( );
+       if ( this != NULL )
+       {
+               this->process = filter_process;
+               if ( arg != NULL )
+                       mlt_properties_set_int( MLT_FILTER_PROPERTIES( this ), "channels", atoi( arg ) );
+               else
+                       mlt_properties_set_int( MLT_FILTER_PROPERTIES( this ), "channels", 2 );
+       }
+       return this;
+}