1 /*****************************************************************************
2 * float32.c : precise float32 audio mixer implementation
3 *****************************************************************************
4 * Copyright (C) 2002 VideoLAN
5 * $Id: float32.c,v 1.10 2004/01/25 17:20:18 kuehne 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 *****************************************************************************/
27 #include <stdlib.h> /* malloc(), free() */
31 #include "audio_output.h"
32 #include "aout_internal.h"
34 /*****************************************************************************
36 *****************************************************************************/
37 static int Create ( vlc_object_t * );
39 static void DoWork ( aout_instance_t *, aout_buffer_t * );
41 /*****************************************************************************
43 *****************************************************************************/
45 set_description( _("Float32 audio mixer") );
46 set_capability( "audio mixer", 10 );
47 set_callbacks( Create, NULL );
50 /*****************************************************************************
51 * Create: allocate mixer
52 *****************************************************************************/
53 static int Create( vlc_object_t *p_this )
55 aout_instance_t * p_aout = (aout_instance_t *)p_this;
57 if ( p_aout->mixer.mixer.i_format != VLC_FOURCC('f','l','3','2') )
62 if ( p_aout->i_nb_inputs == 1 && p_aout->mixer.f_multiplier == 1.0 )
64 /* Tell the trivial mixer to go for it. */
68 p_aout->mixer.pf_do_work = DoWork;
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 )
80 f_multiplier /= i_nb_inputs;
82 for ( i = i_nb_words; i--; )
84 *p_out++ = *p_in++ * f_multiplier;
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 )
95 f_multiplier /= i_nb_inputs;
97 for ( i = i_nb_words; i--; )
99 *p_out++ += *p_in++ * f_multiplier;
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 )
111 int i_nb_inputs = p_aout->i_nb_inputs;
112 float f_multiplier = p_aout->mixer.f_multiplier;
114 int i_nb_channels = aout_FormatNbChannels( &p_aout->mixer.mixer );
116 for ( i_input = 0; i_input < i_nb_inputs; i_input++ )
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;
123 if ( p_input->b_error ) continue;
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
132 if ( i_available_words < i_nb_words )
134 aout_buffer_t * p_old_buffer;
136 if ( i_available_words > 0 )
140 ScaleWords( p_out, p_in, i_available_words,
141 i_nb_inputs, f_multiplier );
145 MeanWords( p_out, p_in, i_available_words,
146 i_nb_inputs, f_multiplier );
150 i_nb_words -= i_available_words;
151 p_out += i_available_words;
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 )
158 msg_Err( p_aout, "internal amix error" );
161 p_in = (float *)p_input->fifo.p_first->p_buffer;
165 if ( i_nb_words > 0 )
169 ScaleWords( p_out, p_in, i_nb_words, i_nb_inputs,
174 MeanWords( p_out, p_in, i_nb_words, i_nb_inputs,
178 p_input->p_first_byte_to_mix = (void *)(p_in