1 /*****************************************************************************
2 * s16tofloat32.c : converter from signed 16 bits integer to float32
3 *****************************************************************************
4 * Copyright (C) 2002-2005 the VideoLAN team
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., 51 Franklin Street, Fifth Floor, Boston MA 02110-1301, 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 *,
41 static void DoWork24 ( aout_instance_t *, aout_filter_t *, aout_buffer_t *,
44 /*****************************************************************************
46 *****************************************************************************/
48 set_category( CAT_AUDIO );
49 set_subcategory( SUBCAT_AUDIO_MISC );
50 set_description( _("audio filter for s16->float32 conversion") );
51 set_capability( "audio filter", 1 );
52 set_callbacks( Create, NULL );
55 /*****************************************************************************
56 * Create: allocate trivial mixer
57 *****************************************************************************
58 * This function allocates and initializes a Crop vout method.
59 *****************************************************************************/
60 static int Create( vlc_object_t *p_this )
62 aout_filter_t * p_filter = (aout_filter_t *)p_this;
64 if ( ( p_filter->input.i_format != AOUT_FMT_S16_NE &&
65 p_filter->input.i_format != AOUT_FMT_S24_NE )
66 || p_filter->output.i_format != VLC_FOURCC('f','l','3','2') )
71 if ( !AOUT_FMTS_SIMILAR( &p_filter->input, &p_filter->output ) )
76 if( p_filter->input.i_format == AOUT_FMT_S24_NE )
77 p_filter->pf_do_work = DoWork24;
79 p_filter->pf_do_work = DoWork;
81 p_filter->b_in_place = VLC_TRUE;
86 /*****************************************************************************
87 * DoWork: convert a buffer
88 *****************************************************************************/
89 static void DoWork( aout_instance_t * p_aout, aout_filter_t * p_filter,
90 aout_buffer_t * p_in_buf, aout_buffer_t * p_out_buf )
92 int i = p_in_buf->i_nb_samples * aout_FormatNbChannels( &p_filter->input );
94 /* We start from the end because b_in_place is true */
95 int16_t * p_in = (int16_t *)p_in_buf->p_buffer + i - 1;
96 float * p_out = (float *)p_out_buf->p_buffer + i - 1;
102 *p_out = (float)*p_in / 32768.0;
104 /* This is walken's trick based on IEEE float format. On my PIII
105 * this takes 16 seconds to perform one billion conversions, instead
106 * of 19 seconds for the above division. */
107 union { float f; int32_t i; } u;
108 u.i = *p_in + 0x43c00000;
109 *p_out = u.f - 384.0;
115 p_out_buf->i_nb_samples = p_in_buf->i_nb_samples;
116 p_out_buf->i_nb_bytes = p_in_buf->i_nb_bytes * 2;
119 static void DoWork24( aout_instance_t * p_aout, aout_filter_t * p_filter,
120 aout_buffer_t * p_in_buf, aout_buffer_t * p_out_buf )
122 int i = p_in_buf->i_nb_samples * aout_FormatNbChannels( &p_filter->input );
124 /* We start from the end because b_in_place is true */
125 uint8_t * p_in = (uint8_t *)p_in_buf->p_buffer + (i - 1) * 3;
126 float * p_out = (float *)p_out_buf->p_buffer + i - 1;
130 #ifdef WORDS_BIGENDIAN
131 *p_out = ((float)( (((int32_t)*(int16_t *)(p_in)) << 8) + p_in[2]))
133 *p_out = ((float)( (((int32_t)*(int16_t *)(p_in+1)) << 8) + p_in[0]))
140 p_out_buf->i_nb_samples = p_in_buf->i_nb_samples;
141 p_out_buf->i_nb_bytes = p_in_buf->i_nb_bytes * 4 / 3;