/***************************************************************************** * headphone.c : headphone virtual spatialization channel mixer module *               -> gives the feeling of a real room with a simple headphone ***************************************************************************** * Copyright (C) 2002 VideoLAN * $Id: headphone.c 10112 2005-03-03 06:58:04Z zorglub $ * * Authors: Boris Dor鑣 <babal@via.ecp.fr> * * 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, USA. *****************************************************************************//***************************************************************************** * Preamble *****************************************************************************/#include <stdlib.h>                                      /* malloc(), free() */#include <string.h>#include <math.h>                                        /* sqrt */#include <vlc/vlc.h>#include "audio_output.h"#include "aout_internal.h"/***************************************************************************** * Local prototypes *****************************************************************************/static int  Create    ( vlc_object_t * );static void Destroy   ( vlc_object_t * );static void DoWork    ( aout_instance_t *, aout_filter_t *, aout_buffer_t *,                        aout_buffer_t * );/***************************************************************************** * Module descriptor *****************************************************************************/#define MODULE_DESCRIPTION N_ ( \     "This effect gives you the feeling that you are standing in a room " \     "with a complete 5.1 speaker set when using only a headphone, " \     "providing a more realistic sound experience. It should also be " \     "more comfortable and less tiring when listening to music for " \     "long periods of time.\nIt works with any source format from mono " \     "to 5.1.")#define HEADPHONE_DIM_TEXT N_("Characteristic dimension")#define HEADPHONE_DIM_LONGTEXT N_( \     "Distance between front left speaker and listener in meters.")vlc_module_begin();    set_description( N_("Headphone channel mixer with virtual spatialization effect") );    set_shortname( _("Headphone effect") );    set_category( CAT_AUDIO );    set_subcategory( SUBCAT_AUDIO_AFILTER );    add_integer( "headphone-dim", 10, NULL, HEADPHONE_DIM_TEXT,                 HEADPHONE_DIM_LONGTEXT, VLC_FALSE );    set_capability( "audio filter", 0 );    set_callbacks( Create, Destroy );    add_shortcut( "headphone" );vlc_module_end();/***************************************************************************** * Internal data structures *****************************************************************************/struct atomic_operation_t{    int i_source_channel_offset;    int i_dest_channel_offset;    unsigned int i_delay;/* in sample unit */    double d_amplitude_factor;};struct aout_filter_sys_t{    size_t i_overflow_buffer_size;/* in bytes */    byte_t * p_overflow_buffer;    unsigned int i_nb_atomic_operations;    struct atomic_operation_t * p_atomic_operations;};/***************************************************************************** * Init: initialize internal data structures * and computes the needed atomic operations *****************************************************************************//* x and z represent the coordinates of the virtual speaker *  relatively to the center of the listener's head, measured in meters : * *  left              right *Z *- *a          head *x *i *s *  rear left    rear right * *          x-axis *  */static void ComputeChannelOperations ( struct aout_filter_sys_t * p_data        , unsigned int i_rate , unsigned int i_next_atomic_operation        , int i_source_channel_offset , double d_x , double d_z        , double d_channel_amplitude_factor ){    double d_c = 340; /*sound celerity (unit: m/s)*/    /* Left ear */    p_data->p_atomic_operations[i_next_atomic_operation]        .i_source_channel_offset = i_source_channel_offset;    p_data->p_atomic_operations[i_next_atomic_operation]        .i_dest_channel_offset = 0;/* left */    p_data->p_atomic_operations[i_next_atomic_operation]        .i_delay = (int)( sqrt( (-0.1-d_x)*(-0.1-d_x) + (0-d_z)*(0-d_z) )                          / d_c * i_rate );    if ( d_x < 0 )    {        p_data->p_atomic_operations[i_next_atomic_operation]            .d_amplitude_factor = d_channel_amplitude_factor * 1.1 / 2;    }    else if ( d_x > 0 )    {        p_data->p_atomic_operations[i_next_atomic_operation]            .d_amplitude_factor = d_channel_amplitude_factor * 0.9 / 2;    }    else    {        p_data->p_atomic_operations[i_next_atomic_operation]            .d_amplitude_factor = d_channel_amplitude_factor / 2;    }    /* Right ear */    p_data->p_atomic_operations[i_next_atomic_operation + 1]        .i_source_channel_offset = i_source_channel_offset;    p_data->p_atomic_operations[i_next_atomic_operation + 1]        .i_dest_channel_offset = 1;/* right */    p_data->p_atomic_operations[i_next_atomic_operation + 1]        .i_delay = (int)( sqrt( (0.1-d_x)*(0.1-d_x) + (0-d_z)*(0-d_z) )                          / d_c * i_rate );    if ( d_x < 0 )    {        p_data->p_atomic_operations[i_next_atomic_operation + 1]            .d_amplitude_factor = d_channel_amplitude_factor * 0.9 / 2;    }    else if ( d_x > 0 )    {        p_data->p_atomic_operations[i_next_atomic_operation + 1]            .d_amplitude_factor = d_channel_amplitude_factor * 1.1 / 2;    }    else    {        p_data->p_atomic_operations[i_next_atomic_operation + 1]            .d_amplitude_factor = d_channel_amplitude_factor / 2;    }}static int Init ( aout_filter_t * p_filter , struct aout_filter_sys_t * p_data        , unsigned int i_nb_channels , uint32_t i_physical_channels        , unsigned int i_rate ){    double d_x = config_GetInt ( p_filter , "headphone-dim" );    double d_z = d_x;    double d_z_rear = -d_x/3;    unsigned int i_next_atomic_operation;    int i_source_channel_offset;    unsigned int i;    if ( p_data == NULL )    {        msg_Dbg ( p_filter, "passing a null pointer as argument" );        return 0;    }    /* Number of elementary operations */    p_data->i_nb_atomic_operations = i_nb_channels * 2;    p_data->p_atomic_operations = malloc ( sizeof(struct atomic_operation_t)            * p_data->i_nb_atomic_operations );    if ( p_data->p_atomic_operations == NULL )    {        msg_Err( p_filter, "out of memory" );        return -1;    }    /* For each virtual speaker, computes elementary wave propagation time     * to each ear */    i_next_atomic_operation = 0;    i_source_channel_offset = 0;    if ( i_physical_channels & AOUT_CHAN_LEFT )    {        ComputeChannelOperations ( p_data , i_rate                , i_next_atomic_operation , i_source_channel_offset                , -d_x , d_z , 2.0 / i_nb_channels );        i_next_atomic_operation += 2;        i_source_channel_offset++;    }    if ( i_physical_channels & AOUT_CHAN_RIGHT )    {        ComputeChannelOperations ( p_data , i_rate                , i_next_atomic_operation , i_source_channel_offset                , d_x , d_z , 2.0 / i_nb_channels );        i_next_atomic_operation += 2;        i_source_channel_offset++;    }    if ( i_physical_channels & AOUT_CHAN_REARLEFT )    {        ComputeChannelOperations ( p_data , i_rate                , i_next_atomic_operation , i_source_channel_offset                , -d_x , d_z_rear , 1.5 / i_nb_channels );        i_next_atomic_operation += 2;        i_source_channel_offset++;    }    if ( i_physical_channels & AOUT_CHAN_REARRIGHT )    {        ComputeChannelOperations ( p_data , i_rate                , i_next_atomic_operation , i_source_channel_offset                , d_x , d_z_rear , 1.5 / i_nb_channels );        i_next_atomic_operation += 2;        i_source_channel_offset++;    }    if ( i_physical_channels & AOUT_CHAN_REARCENTER )    {        ComputeChannelOperations ( p_data , i_rate                , i_next_atomic_operation , i_source_channel_offset                , 0 , -d_z , 1.5 / i_nb_channels );        i_next_atomic_operation += 2;        i_source_channel_offset++;