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>
36 #include <vlc_aout_mixer.h>
38 /*****************************************************************************
40 *****************************************************************************/
41 static int Create ( vlc_object_t * );
42 static aout_buffer_t *DoWork( aout_mixer_t *, unsigned, float );
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 p_mixer->mix = DoWork;
69 /*****************************************************************************
70 * ScaleWords: prepare input words for averaging
71 *****************************************************************************/
72 static void ScaleWords( float * p_out, const float * p_in, size_t i_nb_words,
75 if( f_multiplier == 1.0 )
77 vlc_memcpy( p_out, p_in, i_nb_words * sizeof(float) );
81 for( size_t i = 0; i < i_nb_words; i++ )
82 *p_out++ = *p_in++ * f_multiplier;
85 /*****************************************************************************
86 * DoWork: mix a new output buffer
87 *****************************************************************************
88 * Terminology : in this function a word designates a single float32, eg.
89 * a stereo sample is consituted of two words.
90 *****************************************************************************/
91 static aout_buffer_t *DoWork( aout_mixer_t * p_mixer, unsigned samples,
94 aout_mixer_input_t * p_input = p_mixer->input;
95 const int i_nb_channels = aout_FormatNbChannels( &p_mixer->fmt );
96 int i_nb_words = samples * i_nb_channels;
98 block_t *p_buffer = block_Alloc( i_nb_words * sizeof(float) );
99 if( unlikely( p_buffer == NULL ) )
101 p_buffer->i_nb_samples = samples;
103 float * p_out = (float *)p_buffer->p_buffer;
104 float * p_in = (float *)p_input->begin;
106 f_multiplier *= p_input->multiplier;
110 ptrdiff_t i_available_words = (
111 (float *)p_input->fifo.p_first->p_buffer - p_in)
112 + p_input->fifo.p_first->i_nb_samples
115 if( i_available_words < i_nb_words )
117 aout_buffer_t * p_old_buffer;
119 ScaleWords( p_out, p_in, i_available_words, f_multiplier );
120 i_nb_words -= i_available_words;
121 p_out += i_available_words;
124 p_old_buffer = aout_FifoPop( NULL, &p_input->fifo );
125 aout_BufferFree( p_old_buffer );
126 if( p_input->fifo.p_first == NULL )
128 msg_Err( p_mixer, "internal amix error" );
131 p_in = (float *)p_input->fifo.p_first->p_buffer;
135 ScaleWords( p_out, p_in, i_nb_words, f_multiplier );
136 p_input->begin = (void *)(p_in + i_nb_words);