1 /*****************************************************************************
2 * float32.c : precise float32 audio mixer implementation
3 *****************************************************************************
4 * Copyright (C) 2002 VideoLAN
5 * $Id: float32.c,v 1.2 2002/09/16 20:46:37 massiot Exp $
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., 59 Temple Place - Suite 330, Boston, MA 02111, USA.
22 *****************************************************************************/
24 /*****************************************************************************
26 *****************************************************************************/
28 #include <stdlib.h> /* malloc(), free() */
32 #include "audio_output.h"
33 #include "aout_internal.h"
35 /*****************************************************************************
37 *****************************************************************************/
38 static int Create ( vlc_object_t * );
40 static void DoWork ( aout_instance_t *, aout_buffer_t * );
42 /*****************************************************************************
44 *****************************************************************************/
46 set_description( _("float32 audio mixer module") );
47 set_capability( "audio mixer", 10 );
48 set_callbacks( Create, NULL );
51 /*****************************************************************************
52 * Create: allocate trivial mixer
53 *****************************************************************************/
54 static int Create( vlc_object_t *p_this )
56 aout_instance_t * p_aout = (aout_instance_t *)p_this;
58 if ( p_aout->mixer.mixer.i_format != AOUT_FMT_FLOAT32 )
63 if ( p_aout->i_nb_inputs == 1 && p_aout->mixer.f_multiplier == 1.0 )
65 /* Tell the trivial mixer to go for it. */
69 p_aout->mixer.pf_do_work = DoWork;
74 /*****************************************************************************
75 * ScaleWords: prepare input words for averaging
76 *****************************************************************************/
77 static void ScaleWords( float * p_out, const float * p_in, size_t i_nb_words,
78 int i_nb_inputs, float f_multiplier )
81 f_multiplier /= i_nb_inputs;
83 for ( i = i_nb_words; i--; )
85 *p_out++ = *p_in++ * f_multiplier;
89 /*****************************************************************************
90 * MeanWords: average input words
91 *****************************************************************************/
92 static void MeanWords( float * p_out, const float * p_in, size_t i_nb_words,
93 int i_nb_inputs, float f_multiplier )
96 f_multiplier /= i_nb_inputs;
98 for ( i = i_nb_words; i--; )
100 *p_out++ += *p_in++ * f_multiplier;
104 /*****************************************************************************
105 * DoWork: mix a new output buffer
106 *****************************************************************************
107 * Terminology : in this function a word designates a single float32, eg.
108 * a stereo sample is consituted of two words.
109 *****************************************************************************/
110 static void DoWork( aout_instance_t * p_aout, aout_buffer_t * p_buffer )
112 int i_nb_inputs = p_aout->i_nb_inputs;
115 for ( i_input = 0; i_input < i_nb_inputs; i_input++ )
117 int i_nb_words = p_buffer->i_nb_samples
118 * p_aout->mixer.mixer.i_channels;
119 aout_input_t * p_input = p_aout->pp_inputs[i_input];
120 float * p_out = (float *)p_buffer->p_buffer;
121 float * p_in = (float *)p_input->p_first_byte_to_mix;
125 ptrdiff_t i_available_words = (
126 (float *)p_input->fifo.p_first->p_buffer - p_in)
127 + p_input->fifo.p_first->i_nb_samples
128 * p_aout->mixer.mixer.i_channels;
130 if ( i_available_words < i_nb_words )
132 aout_buffer_t * p_old_buffer;
134 if ( i_available_words > 0 )
138 ScaleWords( p_out, p_in, i_available_words,
139 i_nb_inputs, p_aout->mixer.f_multiplier );
143 MeanWords( p_out, p_in, i_available_words,
144 i_nb_inputs, p_aout->mixer.f_multiplier );
148 i_nb_words -= i_available_words;
149 p_out += i_available_words;
152 p_old_buffer = aout_FifoPop( p_aout, &p_input->fifo );
153 aout_BufferFree( p_old_buffer );
154 if ( p_input->fifo.p_first == NULL )
156 msg_Err( p_aout, "internal amix error" );
159 p_in = (float *)p_input->fifo.p_first->p_buffer;
163 if ( i_nb_words > 0 )
167 ScaleWords( p_out, p_in, i_nb_words, i_nb_inputs,
168 p_aout->mixer.f_multiplier );
172 MeanWords( p_out, p_in, i_nb_words, i_nb_inputs,
173 p_aout->mixer.f_multiplier );
176 p_input->p_first_byte_to_mix = (void *)(p_in