1 /*****************************************************************************
2 * s16tofloat32.c : converter from signed 16 bits integer to float32
3 *****************************************************************************
4 * Copyright (C) 2002 VideoLAN
7 * Authors: Samuel Hocevar <sam@zoy.org>
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_filter_t *, aout_buffer_t *,
42 /*****************************************************************************
44 *****************************************************************************/
46 set_category( CAT_AUDIO );
47 set_subcategory( SUBCAT_AUDIO_MISC );
48 set_description( _("audio filter for s16->float32 conversion") );
49 set_capability( "audio filter", 1 );
50 set_callbacks( Create, NULL );
53 /*****************************************************************************
54 * Create: allocate trivial mixer
55 *****************************************************************************
56 * This function allocates and initializes a Crop vout method.
57 *****************************************************************************/
58 static int Create( vlc_object_t *p_this )
60 aout_filter_t * p_filter = (aout_filter_t *)p_this;
62 if ( p_filter->input.i_format != AOUT_FMT_S16_NE
63 || p_filter->output.i_format != VLC_FOURCC('f','l','3','2') )
68 if ( !AOUT_FMTS_SIMILAR( &p_filter->input, &p_filter->output ) )
73 p_filter->pf_do_work = DoWork;
74 p_filter->b_in_place = VLC_TRUE;
79 /*****************************************************************************
80 * DoWork: convert a buffer
81 *****************************************************************************/
82 static void DoWork( aout_instance_t * p_aout, aout_filter_t * p_filter,
83 aout_buffer_t * p_in_buf, aout_buffer_t * p_out_buf )
85 int i = p_in_buf->i_nb_samples * aout_FormatNbChannels( &p_filter->input );
87 /* We start from the end because b_in_place is true */
88 int16_t * p_in = (int16_t *)p_in_buf->p_buffer + i - 1;
89 float * p_out = (float *)p_out_buf->p_buffer + i - 1;
95 *p_out = (float)*p_in / 32768.0;
97 /* This is walken's trick based on IEEE float format. On my PIII
98 * this takes 16 seconds to perform one billion conversions, instead
99 * of 19 seconds for the above division. */
100 union { float f; int32_t i; } u;
101 u.i = *p_in + 0x43c00000;
102 *p_out = u.f - 384.0;
108 p_out_buf->i_nb_samples = p_in_buf->i_nb_samples;
109 p_out_buf->i_nb_bytes = p_in_buf->i_nb_bytes * 2;