1 /*****************************************************************************
2 * s16tofloat32.c : converter from signed 16 bits integer to float32
3 *****************************************************************************
4 * Copyright (C) 2002 VideoLAN
5 * $Id: s16tofloat32.c,v 1.1 2002/08/21 09:27:40 sam Exp $
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 *****************************************************************************/
28 #include <stdlib.h> /* malloc(), free() */
32 #include "audio_output.h"
33 #include "aout_internal.h"
35 /*****************************************************************************
37 *****************************************************************************/
38 static int Create ( vlc_object_t * );
40 static void DoWork ( aout_instance_t *, aout_filter_t *, aout_buffer_t *,
43 /*****************************************************************************
45 *****************************************************************************/
47 set_description( _("aout filter for s16->float32 conversion") );
48 set_capability( "audio filter", 1 );
49 set_callbacks( Create, NULL );
52 /*****************************************************************************
53 * Create: allocate trivial mixer
54 *****************************************************************************
55 * This function allocates and initializes a Crop vout method.
56 *****************************************************************************/
57 static int Create( vlc_object_t *p_this )
59 aout_filter_t * p_filter = (aout_filter_t *)p_this;
61 if ( p_filter->input.i_format != AOUT_FMT_S16_NE
62 || p_filter->output.i_format != AOUT_FMT_FLOAT32 )
67 if ( !AOUT_FMTS_SIMILAR( &p_filter->input, &p_filter->output ) )
72 p_filter->pf_do_work = DoWork;
73 p_filter->b_in_place = VLC_TRUE;
78 /*****************************************************************************
79 * DoWork: convert a buffer
80 *****************************************************************************/
81 static void DoWork( aout_instance_t * p_aout, aout_filter_t * p_filter,
82 aout_buffer_t * p_in_buf, aout_buffer_t * p_out_buf )
84 int i = p_in_buf->i_nb_samples * p_filter->input.i_channels;
86 /* We start from the end because b_in_place is true */
87 s16 * p_in = (s16 *)p_in_buf->p_buffer + i - 1;
88 float * p_out = (float *)p_out_buf->p_buffer + i - 1;
94 *p_out = (float)*p_in / 32768.0;
96 /* This is walken's trick based on IEEE float format. On my PIII
97 * this takes 16 seconds to perform one billion conversions, instead
98 * of 19 seconds for the above division. */
99 s32 i_out = *p_in + 0x43c00000;
100 float f_out = *(float *)&i_out;
101 *p_out = f_out - 384.0;
107 p_out_buf->i_nb_samples = p_in_buf->i_nb_samples;
108 p_out_buf->i_nb_bytes = p_in_buf->i_nb_bytes * 2;