1 /*****************************************************************************
2 * float32.c : precise float32 audio mixer implementation
3 *****************************************************************************
4 * Copyright (C) 2002 VideoLAN
5 * $Id: float32.c,v 1.1 2002/08/28 22:25:38 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 )
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,
82 for ( i = i_nb_words; i--; )
84 *p_out++ = *p_in++ / i_nb_inputs;
88 /*****************************************************************************
89 * MeanWords: average input words
90 *****************************************************************************/
91 static void MeanWords( float * p_out, const float * p_in, size_t i_nb_words,
96 for ( i = i_nb_words; i--; )
98 *p_out++ += *p_in++ / i_nb_inputs;
102 /*****************************************************************************
103 * DoWork: mix a new output buffer
104 *****************************************************************************
105 * Terminology : in this function a word designates a single float32, eg.
106 * a stereo sample is consituted of two words.
107 *****************************************************************************/
108 static void DoWork( aout_instance_t * p_aout, aout_buffer_t * p_buffer )
110 int i_nb_inputs = p_aout->i_nb_inputs;
113 for ( i_input = 0; i_input < i_nb_inputs; i_input++ )
115 int i_nb_words = p_buffer->i_nb_samples
116 * p_aout->mixer.mixer.i_channels;
117 aout_input_t * p_input = p_aout->pp_inputs[i_input];
118 float * p_out = (float *)p_buffer->p_buffer;
119 float * p_in = (float *)p_input->p_first_byte_to_mix;
123 ptrdiff_t i_available_words = (
124 (float *)p_input->fifo.p_first->p_buffer - p_in)
125 + p_input->fifo.p_first->i_nb_samples
126 * p_aout->mixer.mixer.i_channels;
128 if ( i_available_words < i_nb_words )
130 aout_buffer_t * p_old_buffer;
132 if ( i_available_words > 0 )
136 ScaleWords( p_out, p_in, i_available_words,
141 MeanWords( p_out, p_in, i_available_words,
146 i_nb_words -= i_available_words;
147 p_out += i_available_words;
150 p_old_buffer = aout_FifoPop( p_aout, &p_input->fifo );
151 aout_BufferFree( p_old_buffer );
152 if ( p_input->fifo.p_first == NULL )
154 msg_Err( p_aout, "internal amix error" );
157 p_in = (float *)p_input->fifo.p_first->p_buffer;
161 if ( i_nb_words > 0 )
165 ScaleWords( p_out, p_in, i_nb_words, i_nb_inputs );
169 MeanWords( p_out, p_in, i_nb_words, i_nb_inputs );
172 p_input->p_first_byte_to_mix = (void *)(p_in