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 *****************************************************************************/
33 #include <vlc_common.h>
34 #include <vlc_plugin.h>
37 /*****************************************************************************
39 *****************************************************************************/
40 static int Create ( vlc_object_t * );
42 static void DoWork ( aout_mixer_t *, aout_buffer_t * );
44 /*****************************************************************************
46 *****************************************************************************/
48 set_category( CAT_AUDIO )
49 set_subcategory( SUBCAT_AUDIO_MISC )
50 set_description( N_("Float32 audio mixer") )
51 set_capability( "audio mixer", 10 )
52 set_callbacks( Create, NULL )
55 /*****************************************************************************
56 * Create: allocate mixer
57 *****************************************************************************/
58 static int Create( vlc_object_t *p_this )
60 aout_mixer_t * p_mixer = (aout_mixer_t *)p_this;
62 if ( p_mixer->fmt.i_format != VLC_CODEC_FL32 )
65 /* Use the trivial mixer when we can */
66 if ( p_mixer->input_count == 1 && p_mixer->multiplier == 1.0 )
69 for( i = 0; i < p_mixer->input_count; i++ )
71 if( p_mixer->input[i]->multiplier != 1.0 )
74 if( i >= p_mixer->input_count )
78 p_mixer->mix = 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_mixer_t * p_mixer, aout_buffer_t * p_buffer )
120 const int i_nb_inputs = p_mixer->input_count;
121 const float f_multiplier_global = p_mixer->multiplier;
122 const int i_nb_channels = aout_FormatNbChannels( &p_mixer->fmt );
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_mixer_input_t * p_input = p_mixer->input[i_input];
129 float f_multiplier = f_multiplier_global * p_input->multiplier;
131 float * p_out = (float *)p_buffer->p_buffer;
132 float * p_in = (float *)p_input->begin;
134 if ( p_input->is_invalid )
139 ptrdiff_t i_available_words = (
140 (float *)p_input->fifo.p_first->p_buffer - p_in)
141 + p_input->fifo.p_first->i_nb_samples
144 if ( i_available_words < i_nb_words )
146 aout_buffer_t * p_old_buffer;
148 if ( i_available_words > 0 )
152 ScaleWords( p_out, p_in, i_available_words,
153 i_nb_inputs, f_multiplier );
157 MeanWords( p_out, p_in, i_available_words,
158 i_nb_inputs, f_multiplier );
162 i_nb_words -= i_available_words;
163 p_out += i_available_words;
166 p_old_buffer = aout_FifoPop( NULL, &p_input->fifo );
167 aout_BufferFree( p_old_buffer );
168 if ( p_input->fifo.p_first == NULL )
170 msg_Err( p_mixer, "internal amix error" );
173 p_in = (float *)p_input->fifo.p_first->p_buffer;
177 if ( i_nb_words > 0 )
181 ScaleWords( p_out, p_in, i_nb_words, i_nb_inputs,
186 MeanWords( p_out, p_in, i_nb_words, i_nb_inputs,
190 p_input->begin = (void *)(p_in + i_nb_words);