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->multiplier == 1.0 && p_mixer->input->multiplier == 1.0 )
69 p_mixer->mix = 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,
79 for( size_t i = i_nb_words; i--; )
80 *p_out++ = *p_in++ * f_multiplier;
83 /*****************************************************************************
84 * DoWork: mix a new output buffer
85 *****************************************************************************
86 * Terminology : in this function a word designates a single float32, eg.
87 * a stereo sample is consituted of two words.
88 *****************************************************************************/
89 static void DoWork( aout_mixer_t * p_mixer, aout_buffer_t * p_buffer )
91 const float f_multiplier_global = p_mixer->multiplier;
92 const int i_nb_channels = aout_FormatNbChannels( &p_mixer->fmt );
94 int i_nb_words = p_buffer->i_nb_samples * i_nb_channels;
95 aout_mixer_input_t * p_input = p_mixer->input;
96 float f_multiplier = f_multiplier_global * p_input->multiplier;
98 float * p_out = (float *)p_buffer->p_buffer;
99 float * p_in = (float *)p_input->begin;
103 ptrdiff_t i_available_words = (
104 (float *)p_input->fifo.p_first->p_buffer - p_in)
105 + p_input->fifo.p_first->i_nb_samples
108 if( i_available_words < i_nb_words )
110 aout_buffer_t * p_old_buffer;
112 if( i_available_words > 0 )
113 ScaleWords( p_out, p_in, i_available_words, f_multiplier );
115 i_nb_words -= i_available_words;
116 p_out += i_available_words;
119 p_old_buffer = aout_FifoPop( NULL, &p_input->fifo );
120 aout_BufferFree( p_old_buffer );
121 if( p_input->fifo.p_first == NULL )
123 msg_Err( p_mixer, "internal amix error" );
126 p_in = (float *)p_input->fifo.p_first->p_buffer;
131 ScaleWords( p_out, p_in, i_nb_words, f_multiplier );
132 p_input->begin = (void *)(p_in + i_nb_words);