1 /*****************************************************************************
2 * trivial.c : trivial channel mixer plug-in (drops unwanted channels)
3 *****************************************************************************
4 * Copyright (C) 2002 VideoLAN
5 * $Id: trivial.c,v 1.2 2002/08/28 22:25:38 massiot Exp $
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., 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( _("audio filter for trivial channel mixing") );
48 set_capability( "audio filter", 1 );
49 set_callbacks( Create, NULL );
52 /*****************************************************************************
53 * Create: allocate trivial channel mixer
54 *****************************************************************************/
55 static int Create( vlc_object_t *p_this )
57 aout_filter_t * p_filter = (aout_filter_t *)p_this;
59 if ( p_filter->input.i_channels == p_filter->output.i_channels
60 || p_filter->input.i_format != p_filter->output.i_format
61 || p_filter->input.i_rate != p_filter->output.i_rate
62 || (p_filter->input.i_format != AOUT_FMT_FLOAT32
63 && p_filter->input.i_format != AOUT_FMT_FIXED32) )
68 p_filter->pf_do_work = DoWork;
69 if ( p_filter->input.i_channels > p_filter->output.i_channels )
72 p_filter->b_in_place = 1;
77 p_filter->b_in_place = 0;
83 /*****************************************************************************
84 * SparseCopy: trivially downmix or upmix a buffer
85 *****************************************************************************/
86 static void SparseCopy( s32 * p_dest, const s32 * p_src, size_t i_len,
87 int i_output_stride, int i_input_stride )
90 for ( i = i_len; i--; )
93 for ( j = 0; j < i_output_stride; j++ )
97 p_src += i_input_stride;
98 p_dest += i_output_stride;
102 /*****************************************************************************
103 * DoWork: convert a buffer
104 *****************************************************************************/
105 static void DoWork( aout_instance_t * p_aout, aout_filter_t * p_filter,
106 aout_buffer_t * p_in_buf, aout_buffer_t * p_out_buf )
108 SparseCopy( (s32 *)p_out_buf->p_buffer, (s32 *)p_in_buf->p_buffer,
109 p_in_buf->i_nb_samples, p_filter->output.i_channels,
110 p_filter->input.i_channels );
112 p_out_buf->i_nb_samples = p_in_buf->i_nb_samples;
113 p_out_buf->i_nb_bytes = p_in_buf->i_nb_bytes * p_filter->output.i_channels
114 / p_filter->input.i_channels;