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 )
68 if( p_mixer->input[0]->multiplier == 1.0 )
72 p_mixer->mix = DoWork;
76 /*****************************************************************************
77 * ScaleWords: prepare input words for averaging
78 *****************************************************************************/
79 static void ScaleWords( float * p_out, const float * p_in, size_t i_nb_words,
80 int i_nb_inputs, float f_multiplier )
83 f_multiplier /= i_nb_inputs;
85 for ( i = i_nb_words; i--; )
87 *p_out++ = *p_in++ * f_multiplier;
91 /*****************************************************************************
92 * MeanWords: average input words
93 *****************************************************************************/
94 static void MeanWords( float * p_out, const float * p_in, size_t i_nb_words,
95 int i_nb_inputs, float f_multiplier )
98 f_multiplier /= i_nb_inputs;
100 for ( i = i_nb_words; i--; )
102 *p_out++ += *p_in++ * f_multiplier;
106 /*****************************************************************************
107 * DoWork: mix a new output buffer
108 *****************************************************************************
109 * Terminology : in this function a word designates a single float32, eg.
110 * a stereo sample is consituted of two words.
111 *****************************************************************************/
112 static void DoWork( aout_mixer_t * p_mixer, aout_buffer_t * p_buffer )
114 const int i_nb_inputs = p_mixer->input_count;
115 const float f_multiplier_global = p_mixer->multiplier;
116 const int i_nb_channels = aout_FormatNbChannels( &p_mixer->fmt );
119 for ( i_input = 0; i_input < i_nb_inputs; i_input++ )
121 int i_nb_words = p_buffer->i_nb_samples * i_nb_channels;
122 aout_mixer_input_t * p_input = p_mixer->input[i_input];
123 float f_multiplier = f_multiplier_global * p_input->multiplier;
125 float * p_out = (float *)p_buffer->p_buffer;
126 float * p_in = (float *)p_input->begin;
128 if ( p_input->is_invalid )
133 ptrdiff_t i_available_words = (
134 (float *)p_input->fifo.p_first->p_buffer - p_in)
135 + p_input->fifo.p_first->i_nb_samples
138 if ( i_available_words < i_nb_words )
140 aout_buffer_t * p_old_buffer;
142 if ( i_available_words > 0 )
146 ScaleWords( p_out, p_in, i_available_words,
147 i_nb_inputs, f_multiplier );
151 MeanWords( p_out, p_in, i_available_words,
152 i_nb_inputs, f_multiplier );
156 i_nb_words -= i_available_words;
157 p_out += i_available_words;
160 p_old_buffer = aout_FifoPop( NULL, &p_input->fifo );
161 aout_BufferFree( p_old_buffer );
162 if ( p_input->fifo.p_first == NULL )
164 msg_Err( p_mixer, "internal amix error" );
167 p_in = (float *)p_input->fifo.p_first->p_buffer;
171 if ( i_nb_words > 0 )
175 ScaleWords( p_out, p_in, i_nb_words, i_nb_inputs,
180 MeanWords( p_out, p_in, i_nb_words, i_nb_inputs,
184 p_input->begin = (void *)(p_in + i_nb_words);