modules/audio_filter/stereo_widen.c

   1 /*****************************************************************************
   2  * stereo_widen.c : simple stereo widening effect
   3  *****************************************************************************
   4  * Copyright (C) 2012 VLC authors and VideoLAN
   5  *
   6  * Author : Sukrit Sangwan < sukritsangwan at gmail dot com >
   7  *
   8  * This program is free software; you can redistribute it and/or modify it
   9  * under the terms of the GNU Lesser General Public License as published by
  10  * the Free Software Foundation; either version 2.1 of the License, or
  11  * (at your option) any later version.
  12  *
  13  * This program is distributed in the hope that it will be useful,
  14  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  15  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
  16  * GNU Lesser General Public License for more details.
  17  *
  18  * You should have received a copy of the GNU Lesser General Public License
  19  * along with this program; if not, write to the Free Software Foundation,
  20  * Inc., 51 Franklin Street, Fifth Floor, Boston MA 02110-1301, USA.
  21  *****************************************************************************/
  22
  23 #ifdef HAVE_CONFIG_H
  24 # include "config.h"
  25 #endif
  26
  27 #include <vlc_common.h>
  28 #include <vlc_aout.h>
  29 #include <vlc_filter.h>
  30 #include <vlc_plugin.h>
  31
  32 /*****************************************************************************
  33  * Local prototypes
  34  *****************************************************************************/
  35 static int  Open ( vlc_object_t * );
  36 static void Close( vlc_object_t * );
  37
  38 static block_t *Filter ( filter_t *, block_t * );
  39 static int paramCallback( vlc_object_t *, char const *, vlc_value_t ,
  40                             vlc_value_t , void * );
  41
  42 struct filter_sys_t
  43 {
  44     float *pf_ringbuf;  /* circular buffer to store samples */
  45     float *pf_write;    /* where to write current sample    */
  46     size_t i_len;       /* delay in number of samples       */
  47     float f_delay;      /* delay in milliseconds            */
  48     float f_feedback;
  49     float f_crossfeed;
  50     float f_dry_mix;
  51 };
  52
  53 #define HELP_TEXT N_("This filter enhances the stereo effect by "\
  54             "suppressing mono (signal common to both channels) "\
  55             "and by delaying the signal of left into right and vice versa, "\
  56             "thereby widening the stereo effect.")
  57 #define DELAY_TEXT N_("Delay time")
  58 #define DELAY_LONGTEXT N_("Time in ms of the delay of left signal into right "\
  59             "and vice versa.")
  60 #define FEEDBACK_TEXT N_("Feedback gain")
  61 #define FEEDBACK_LONGTEXT N_("Amount of gain in delayed left signal into "\
  62             "right and vice versa. Gives a delay effect of left signal in "\
  63             "right output and vice versa which gives widening effect.")
  64 #define CROSSFEED_TEXT N_("Crossfeed")
  65 #define CROSSFEED_LONGTEXT N_("Cross feed of left into right with inverted "\
  66             "phase. This helps in suppressing the mono. If the value is 1 it "\
  67             "will cancel all the signal common to both channels.")
  68 #define DRYMIX_TEXT N_("Dry mix")
  69 #define DRYMIX_LONGTEXT N_("Level of input signal of original channel.")
  70
  71 #define CONFIG_PREFIX "stereowiden-"
  72
  73 /*****************************************************************************
  74  * Module descriptor
  75  *****************************************************************************/
  76 vlc_module_begin ()
  77     set_shortname( N_("Stereo Enhancer") )
  78     set_description( N_("Simple stereo widening effect") )
  79     set_help( HELP_TEXT )
  80     set_category( CAT_AUDIO )
  81     set_subcategory( SUBCAT_AUDIO_AFILTER )
  82     set_capability( "audio filter", 0 )
  83     set_callbacks( Open, Close )
  84
  85     add_float_with_range( CONFIG_PREFIX "delay", 20, 1, 100,
  86         DELAY_TEXT, DELAY_LONGTEXT, true )
  87     add_float_with_range( CONFIG_PREFIX "feedback", 0.3, 0.0, 0.9,
  88         FEEDBACK_TEXT, FEEDBACK_LONGTEXT, true )
  89     add_float_with_range( CONFIG_PREFIX "crossfeed", 0.3, 0.0, 0.8,
  90         CROSSFEED_TEXT, CROSSFEED_LONGTEXT, true )
  91     add_float_with_range( CONFIG_PREFIX "dry-mix", 0.8, 0.0, 1.0,
  92         DRYMIX_TEXT, DRYMIX_LONGTEXT, true )
  93 vlc_module_end ()
  94
  95 /*****************************************************************************
  96  * Open: Allocate buffer
  97  *****************************************************************************/
  98 static int MakeRingBuffer( float **pp_buffer, size_t *pi_buffer,
  99                            float **pp_write, float f_delay, unsigned i_rate )
 100 {
 101     const size_t i_size = (2 * (size_t)(1 + f_delay * i_rate / 1000));
 102
 103     if( unlikely(SIZE_MAX / sizeof(float) < i_size) )
 104         return VLC_EGENERIC;
 105
 106     float *p_realloc = realloc( *pp_buffer, i_size * sizeof(float) );
 107     if( !p_realloc )
 108         return VLC_ENOMEM;
 109
 110     memset( p_realloc, 0, i_size * sizeof(float) );
 111     *pp_write = *pp_buffer = p_realloc;
 112     *pi_buffer = i_size;
 113
 114     return VLC_SUCCESS;
 115 }
 116
 117 static int Open( vlc_object_t *obj )
 118 {
 119     filter_t *p_filter  = (filter_t *)obj;
 120     vlc_object_t *p_aout = p_filter->obj.parent;
 121     filter_sys_t *p_sys;
 122
 123     if( p_filter->fmt_in.audio.i_format != VLC_CODEC_FL32 ||
 124      !AOUT_FMTS_IDENTICAL( &p_filter->fmt_in.audio, &p_filter->fmt_out.audio) )
 125         return VLC_EGENERIC;
 126
 127     if( p_filter->fmt_in.audio.i_channels != 2 )
 128     {
 129         msg_Err ( p_filter, "stereo enhance requires stereo" );
 130         return VLC_EGENERIC;
 131     }
 132
 133     p_sys = p_filter->p_sys = malloc( sizeof(filter_sys_t) );
 134     if( unlikely(!p_sys) )
 135         return VLC_ENOMEM;
 136
 137 #define CREATE_VAR( stor, var ) \
 138     p_sys->stor = var_CreateGetFloat( p_aout, var ); \
 139     var_AddCallback( p_aout, var, paramCallback, p_sys );
 140
 141     CREATE_VAR( f_delay,     CONFIG_PREFIX "delay" )
 142     CREATE_VAR( f_feedback,  CONFIG_PREFIX "feedback" )
 143     CREATE_VAR( f_crossfeed, CONFIG_PREFIX "crossfeed" )
 144     CREATE_VAR( f_dry_mix,   CONFIG_PREFIX "dry-mix" )
 145
 146     /* Compute buffer length and allocate space */
 147     p_sys->pf_ringbuf = NULL;
 148     p_sys->i_len = 0;
 149     if( MakeRingBuffer( &p_sys->pf_ringbuf, &p_sys->i_len, &p_sys->pf_write,
 150                         p_sys->f_delay, p_filter->fmt_in.audio.i_rate ) != VLC_SUCCESS )
 151     {
 152         Close( obj );
 153         return VLC_ENOMEM;
 154     }
 155
 156     p_filter->pf_audio_filter = Filter;
 157     return VLC_SUCCESS;
 158 }
 159
 160 /*****************************************************************************
 161  * Filter: process each sample
 162  *****************************************************************************/
 163 static block_t *Filter( filter_t *p_filter, block_t *p_block )
 164 {
 165     filter_sys_t *p_sys = p_filter->p_sys;
 166     float *p_out = (float *)p_block->p_buffer;
 167     float *pf_read;
 168
 169     for (unsigned i = p_block->i_nb_samples; i > 0; i--)
 170     {
 171         pf_read = p_sys->pf_write + 2;
 172         /* if at end of buffer put read ptr at begin */
 173         if( pf_read >= p_sys->pf_ringbuf + p_sys->i_len )
 174             pf_read = p_sys->pf_ringbuf;
 175
 176         float left  = p_out[0];
 177         float right = p_out[1];
 178
 179         *(p_out++) = p_sys->f_dry_mix * left  - p_sys->f_crossfeed * right
 180                         - p_sys->f_feedback * pf_read[1];
 181         *(p_out++) = p_sys->f_dry_mix * right - p_sys->f_crossfeed * left
 182                         - p_sys->f_feedback * pf_read[0];
 183         *(p_sys->pf_write++) = left ;
 184         *(p_sys->pf_write++) = right;
 185
 186         /* if at end of buffer place pf_write at begin */
 187         if( p_sys->pf_write  == p_sys->pf_ringbuf + p_sys->i_len )
 188             p_sys->pf_write  =  p_sys->pf_ringbuf;
 189     }
 190
 191     return p_block;
 192 }
 193
 194 /*****************************************************************************
 195  * Close: close the plugin
 196  *****************************************************************************/
 197 static void Close( vlc_object_t *obj )
 198 {
 199     filter_t *p_filter  = (filter_t *)obj;
 200     vlc_object_t *p_aout = p_filter->obj.parent;
 201     filter_sys_t *p_sys = p_filter->p_sys;
 202
 203 #define DEL_VAR(var) \
 204     var_DelCallback( p_aout, var, paramCallback, p_sys ); \
 205     var_Destroy( p_aout, var );
 206
 207     DEL_VAR( CONFIG_PREFIX "feedback" );
 208     DEL_VAR( CONFIG_PREFIX "crossfeed" );
 209     DEL_VAR( CONFIG_PREFIX "dry-mix" );
 210     DEL_VAR( CONFIG_PREFIX "delay" );
 211
 212     free( p_sys->pf_ringbuf );
 213     free( p_sys );
 214 }
 215
 216
 217 /**********************************************************************
 218  * Callback to update params on the fly
 219  **********************************************************************/
 220 static int paramCallback( vlc_object_t *p_this, char const *psz_var,
 221                             vlc_value_t oldval, vlc_value_t newval,
 222                             void *p_data )
 223 {
 224     filter_t *p_filter = (filter_t *)p_this;
 225     filter_sys_t *p_sys = (filter_sys_t *) p_data;
 226
 227     VLC_UNUSED(oldval);
 228     VLC_UNUSED(p_this);
 229
 230     if( !strcmp( psz_var, CONFIG_PREFIX "delay" ) )
 231     {
 232         if( MakeRingBuffer( &p_sys->pf_ringbuf, &p_sys->i_len, &p_sys->pf_write,
 233                             newval.f_float, p_filter->fmt_in.audio.i_rate ) != VLC_SUCCESS )
 234         {
 235             msg_Dbg( p_filter, "Couldnt allocate buffer for delay" );
 236         }
 237         else
 238         {
 239             p_sys->f_delay = newval.f_float;
 240         }
 241     }
 242     else if( !strcmp( psz_var, CONFIG_PREFIX "feedback" ) )
 243         p_sys->f_feedback = newval.f_float;
 244     else if( !strcmp( psz_var, CONFIG_PREFIX "crossfeed" ) )
 245         p_sys->f_feedback = newval.f_float;
 246     else if( !strcmp( psz_var, CONFIG_PREFIX "dry-mix" ) )
 247         p_sys->f_dry_mix = newval.f_float;
 248
 249     return VLC_SUCCESS;
 250 }