/*
 * transition_mix.c -- mix two audio streams
 * Copyright (C) 2003-2004 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 "transition_mix.h"
#include <framework/mlt_frame.h>

#include <stdio.h>
#include <stdlib.h>


/** Get the audio.
*/

static int transition_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 a_props = mlt_frame_properties( frame );

	// Get the b frame from the stack
	mlt_frame b_frame = mlt_frame_pop_frame( frame );

	// Get the properties of the b frame
	mlt_properties b_props = mlt_frame_properties( b_frame );

	// Restore the original get_audio
	frame->get_audio = mlt_properties_get_data( a_props, "mix.get_audio", NULL );

	double mix = 0.5;
	if ( mlt_properties_get( b_props, "audio.mix" ) != NULL )
		mix = mlt_properties_get_double( b_props, "audio.mix" );
	mlt_frame_mix_audio( frame, b_frame, mix, buffer, format, frequency, channels, samples );

	// Push the b_frame back on for get_image
	mlt_frame_push_frame( frame, b_frame );

	return 0;
}


/** Mix transition processing.
*/

static mlt_frame transition_process( mlt_transition this, mlt_frame a_frame, mlt_frame b_frame )
{
	mlt_properties properties = mlt_transition_properties( this );
	mlt_properties b_props = mlt_frame_properties( b_frame );

	// Only if mix is specified, otherwise a producer may set the mix
	if ( mlt_properties_get( properties, "mix" ) != NULL )
	{
		// A negative means crossfade
		if ( mlt_properties_get_double( properties, "mix" ) < 0 )
		{
			// Determine the time position of this frame in the transition duration
			mlt_position in = mlt_transition_get_in( this );
			mlt_position out = mlt_transition_get_out( this );
			mlt_position time = mlt_frame_get_position( b_frame );
			double mix = ( double )( time - in ) / ( double )( out - in + 1 );
			mlt_properties_set_double( b_props, "audio.mix", mix );
		}
		else
			mlt_properties_set_double( b_props, "audio.mix", mlt_properties_get_double( properties, "mix" ) );
	}
			
	// Backup the original get_audio (it's still needed)
	mlt_properties_set_data( mlt_frame_properties( a_frame ), "mix.get_audio", a_frame->get_audio, 0, NULL, NULL );

	// Override the get_audio method
	a_frame->get_audio = transition_get_audio;
	
	mlt_frame_push_frame( a_frame, b_frame );
	
	return a_frame;
}

/** Constructor for the transition.
*/

mlt_transition transition_mix_init( char *arg )
{
	mlt_transition this = calloc( sizeof( struct mlt_transition_s ), 1 );
	if ( this != NULL && mlt_transition_init( this, NULL ) == 0 )
	{
		this->process = transition_process;
		if ( arg != NULL )
			mlt_properties_set_double( mlt_transition_properties( this ), "mix", atof( arg ) );
	}
	return this;
}