3e93914b9077a5f59eedcf7a4df03e98817bff55
[vlc.git] / modules / audio_mixer / float32.c
1 /*****************************************************************************
2  * float32.c : precise float32 audio mixer implementation
3  *****************************************************************************
4  * Copyright (C) 2002 VideoLAN
5  * $Id: float32.c,v 1.9 2003/03/30 18:14:36 gbazin Exp $
6  *
7  * Authors: Christophe Massiot <massiot@via.ecp.fr>
8  *
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.
13  * 
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.
18  *
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  *****************************************************************************/
23
24 /*****************************************************************************
25  * Preamble
26  *****************************************************************************/
27 #include <stdlib.h>                                      /* malloc(), free() */
28 #include <string.h>
29
30 #include <vlc/vlc.h>
31 #include "audio_output.h"
32 #include "aout_internal.h"
33
34 /*****************************************************************************
35  * Local prototypes
36  *****************************************************************************/
37 static int  Create    ( vlc_object_t * );
38
39 static void DoWork    ( aout_instance_t *, aout_buffer_t * );
40
41 /*****************************************************************************
42  * Module descriptor
43  *****************************************************************************/
44 vlc_module_begin();
45     set_description( _("float32 audio mixer") );
46     set_capability( "audio mixer", 10 );
47     set_callbacks( Create, NULL );
48 vlc_module_end();
49
50 /*****************************************************************************
51  * Create: allocate mixer
52  *****************************************************************************/
53 static int Create( vlc_object_t *p_this )
54 {
55     aout_instance_t * p_aout = (aout_instance_t *)p_this;
56
57     if ( p_aout->mixer.mixer.i_format != VLC_FOURCC('f','l','3','2') )
58     {
59         return -1;
60     }
61
62     if ( p_aout->i_nb_inputs == 1 && p_aout->mixer.f_multiplier == 1.0 )
63     {
64         /* Tell the trivial mixer to go for it. */
65         return -1;
66     }
67
68     p_aout->mixer.pf_do_work = DoWork;
69
70     return 0;
71 }
72
73 /*****************************************************************************
74  * ScaleWords: prepare input words for averaging
75  *****************************************************************************/
76 static void ScaleWords( float * p_out, const float * p_in, size_t i_nb_words,
77                         int i_nb_inputs, float f_multiplier )
78 {
79     int i;
80     f_multiplier /= i_nb_inputs;
81
82     for ( i = i_nb_words; i--; )
83     {
84         *p_out++ = *p_in++ * f_multiplier;
85     }
86 }
87
88 /*****************************************************************************
89  * MeanWords: average input words
90  *****************************************************************************/
91 static void MeanWords( float * p_out, const float * p_in, size_t i_nb_words,
92                        int i_nb_inputs, float f_multiplier )
93 {
94     int i;
95     f_multiplier /= i_nb_inputs;
96
97     for ( i = i_nb_words; i--; )
98     {
99         *p_out++ += *p_in++ * f_multiplier;
100     }
101 }
102
103 /*****************************************************************************
104  * DoWork: mix a new output buffer
105  *****************************************************************************
106  * Terminology : in this function a word designates a single float32, eg.
107  * a stereo sample is consituted of two words.
108  *****************************************************************************/
109 static void DoWork( aout_instance_t * p_aout, aout_buffer_t * p_buffer )
110 {
111     int i_nb_inputs = p_aout->i_nb_inputs;
112     float f_multiplier = p_aout->mixer.f_multiplier;
113     int i_input;
114     int i_nb_channels = aout_FormatNbChannels( &p_aout->mixer.mixer );
115
116     for ( i_input = 0; i_input < i_nb_inputs; i_input++ )
117     {
118         int i_nb_words = p_buffer->i_nb_samples * i_nb_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;
122
123         if ( p_input->b_error ) continue;
124
125         for ( ; ; )
126         {
127             ptrdiff_t i_available_words = (
128                  (float *)p_input->fifo.p_first->p_buffer - p_in)
129                                    + p_input->fifo.p_first->i_nb_samples
130                                    * i_nb_channels;
131
132             if ( i_available_words < i_nb_words )
133             {
134                 aout_buffer_t * p_old_buffer;
135
136                 if ( i_available_words > 0 )
137                 {
138                     if ( !i_input )
139                     {
140                         ScaleWords( p_out, p_in, i_available_words,
141                                     i_nb_inputs, f_multiplier );
142                     }
143                     else
144                     {
145                         MeanWords( p_out, p_in, i_available_words,
146                                    i_nb_inputs, f_multiplier );
147                     }
148                 }
149
150                 i_nb_words -= i_available_words;
151                 p_out += i_available_words;
152
153                 /* Next buffer */
154                 p_old_buffer = aout_FifoPop( p_aout, &p_input->fifo );
155                 aout_BufferFree( p_old_buffer );
156                 if ( p_input->fifo.p_first == NULL )
157                 {
158                     msg_Err( p_aout, "internal amix error" );
159                     return;
160                 }
161                 p_in = (float *)p_input->fifo.p_first->p_buffer;
162             }
163             else
164             {
165                 if ( i_nb_words > 0 )
166                 {
167                     if ( !i_input )
168                     {
169                         ScaleWords( p_out, p_in, i_nb_words, i_nb_inputs,
170                                     f_multiplier );
171                     }
172                     else
173                     {
174                         MeanWords( p_out, p_in, i_nb_words, i_nb_inputs,
175                                    f_multiplier );
176                     }
177                 }
178                 p_input->p_first_byte_to_mix = (void *)(p_in
179                                             + i_nb_words);
180                 break;
181             }
182         }
183     }
184 }
185