1 /*****************************************************************************
2 * float32.c : precise float32 audio mixer implementation
3 *****************************************************************************
4 * Copyright (C) 2002 the VideoLAN team
7 * Authors: Christophe Massiot <massiot@via.ecp.fr>
9 * This program is free software; you can redistribute it and/or modify
10 * it under the terms of the GNU General Public License as published by
11 * the Free Software Foundation; either version 2 of the License, or
12 * (at your option) any later version.
14 * This program is distributed in the hope that it will be useful,
15 * but WITHOUT ANY WARRANTY; without even the implied warranty of
16 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
17 * GNU General Public License for more details.
19 * You should have received a copy of the GNU General Public License
20 * along with this program; if not, write to the Free Software
21 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston MA 02110-1301, USA.
22 *****************************************************************************/
24 /*****************************************************************************
26 *****************************************************************************/
35 /*****************************************************************************
37 *****************************************************************************/
38 static int Create ( vlc_object_t * );
40 static void DoWork ( aout_instance_t *, aout_buffer_t * );
42 /*****************************************************************************
44 *****************************************************************************/
46 set_category( CAT_AUDIO );
47 set_subcategory( SUBCAT_AUDIO_MISC );
48 set_description( _("Float32 audio mixer") );
49 set_capability( "audio mixer", 10 );
50 set_callbacks( Create, NULL );
53 /*****************************************************************************
54 * Create: allocate mixer
55 *****************************************************************************/
56 static int Create( vlc_object_t *p_this )
58 aout_instance_t * p_aout = (aout_instance_t *)p_this;
60 if ( p_aout->mixer.mixer.i_format != VLC_FOURCC('f','l','3','2') )
65 /* Use the trivial mixer when we can */
66 if ( p_aout->i_nb_inputs == 1 && p_aout->mixer.f_multiplier == 1.0 )
69 for( i = 0; i < p_aout->i_nb_inputs; i++ )
71 if( p_aout->pp_inputs[i]->f_multiplier != 1.0 )
74 if( i >= p_aout->i_nb_inputs )
78 p_aout->mixer.pf_do_work = DoWork;
82 /*****************************************************************************
83 * ScaleWords: prepare input words for averaging
84 *****************************************************************************/
85 static void ScaleWords( float * p_out, const float * p_in, size_t i_nb_words,
86 int i_nb_inputs, float f_multiplier )
89 f_multiplier /= i_nb_inputs;
91 for ( i = i_nb_words; i--; )
93 *p_out++ = *p_in++ * f_multiplier;
97 /*****************************************************************************
98 * MeanWords: average input words
99 *****************************************************************************/
100 static void MeanWords( float * p_out, const float * p_in, size_t i_nb_words,
101 int i_nb_inputs, float f_multiplier )
104 f_multiplier /= i_nb_inputs;
106 for ( i = i_nb_words; i--; )
108 *p_out++ += *p_in++ * f_multiplier;
112 /*****************************************************************************
113 * DoWork: mix a new output buffer
114 *****************************************************************************
115 * Terminology : in this function a word designates a single float32, eg.
116 * a stereo sample is consituted of two words.
117 *****************************************************************************/
118 static void DoWork( aout_instance_t * p_aout, aout_buffer_t * p_buffer )
120 const int i_nb_inputs = p_aout->i_nb_inputs;
121 const float f_multiplier_global = p_aout->mixer.f_multiplier;
122 const int i_nb_channels = aout_FormatNbChannels( &p_aout->mixer.mixer );
125 for ( i_input = 0; i_input < i_nb_inputs; i_input++ )
127 int i_nb_words = p_buffer->i_nb_samples * i_nb_channels;
128 aout_input_t * p_input = p_aout->pp_inputs[i_input];
129 float f_multiplier = f_multiplier_global * p_input->f_multiplier;
131 float * p_out = (float *)p_buffer->p_buffer;
132 float * p_in = (float *)p_input->p_first_byte_to_mix;
134 if ( p_input->b_error ) continue;
138 ptrdiff_t i_available_words = (
139 (float *)p_input->fifo.p_first->p_buffer - p_in)
140 + p_input->fifo.p_first->i_nb_samples
143 if ( i_available_words < i_nb_words )
145 aout_buffer_t * p_old_buffer;
147 if ( i_available_words > 0 )
151 ScaleWords( p_out, p_in, i_available_words,
152 i_nb_inputs, f_multiplier );
156 MeanWords( p_out, p_in, i_available_words,
157 i_nb_inputs, f_multiplier );
161 i_nb_words -= i_available_words;
162 p_out += i_available_words;
165 p_old_buffer = aout_FifoPop( p_aout, &p_input->fifo );
166 aout_BufferFree( p_old_buffer );
167 if ( p_input->fifo.p_first == NULL )
169 msg_Err( p_aout, "internal amix error" );
172 p_in = (float *)p_input->fifo.p_first->p_buffer;
176 if ( i_nb_words > 0 )
180 ScaleWords( p_out, p_in, i_nb_words, i_nb_inputs,
185 MeanWords( p_out, p_in, i_nb_words, i_nb_inputs,
189 p_input->p_first_byte_to_mix = (void *)(p_in