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96 lines
2.8 KiB
96 lines
2.8 KiB
/*
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* filter_mono.c -- mix all channels to a mono signal across n channels
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* Copyright (C) 2003-2006 Ushodaya Enterprises Limited
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* Author: Dan Dennedy <dan@dennedy.org>
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*
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* This library is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation; either
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* version 2.1 of the License, or (at your option) any later version.
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*
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* This library is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with this library; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
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*/
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#include "filter_mono.h"
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#include <framework/mlt_frame.h>
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#include <stdio.h>
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#include <stdlib.h>
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/** Get the audio.
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*/
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static int filter_get_audio( mlt_frame frame, int16_t **buffer, mlt_audio_format *format, int *frequency, int *channels, int *samples )
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{
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// Get the properties of the a frame
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mlt_properties properties = MLT_FRAME_PROPERTIES( frame );
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int channels_out = mlt_properties_get_int( properties, "mono.channels" );
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int i, j, size;
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int16_t *new_buffer;
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// Get the producer's audio
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mlt_frame_get_audio( frame, buffer, format, frequency, channels, samples );
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size = *samples * channels_out * sizeof( int16_t );
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new_buffer = mlt_pool_alloc( size );
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mlt_properties_set_data( properties, "audio", new_buffer, size, ( mlt_destructor )mlt_pool_release, NULL );
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// Mix
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for ( i = 0; i < *samples; i++ )
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{
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int16_t mixdown = 0;
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for ( j = 0; j < *channels; j++ )
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mixdown += (*buffer)[ ( i * *channels ) + j ] / *channels;
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for ( j = 0; j < channels_out; j++ )
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new_buffer[ ( i * channels_out ) + j ] = mixdown;
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}
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// Apply results
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*buffer = new_buffer;
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*channels = channels_out;
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return 0;
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}
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/** Filter processing.
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*/
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static mlt_frame filter_process( mlt_filter this, mlt_frame frame )
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{
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mlt_properties properties = MLT_FILTER_PROPERTIES( this );
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mlt_properties frame_props = MLT_FRAME_PROPERTIES( frame );
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// Propogate the parameters
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mlt_properties_set_int( frame_props, "mono.channels", mlt_properties_get_int( properties, "channels" ) );
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// Override the get_audio method
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mlt_frame_push_audio( frame, filter_get_audio );
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return frame;
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}
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/** Constructor for the filter.
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*/
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mlt_filter filter_mono_init( char *arg )
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{
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mlt_filter this = mlt_filter_new( );
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if ( this != NULL )
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{
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this->process = filter_process;
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if ( arg != NULL )
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mlt_properties_set_int( MLT_FILTER_PROPERTIES( this ), "channels", atoi( arg ) );
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else
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mlt_properties_set_int( MLT_FILTER_PROPERTIES( this ), "channels", 2 );
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}
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return this;
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}
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