1 /*****************************************************************************
2 * trivial.c : trivial channel mixer plug-in (drops unwanted channels)
3 *****************************************************************************
4 * Copyright (C) 2002 VideoLAN
5 * $Id: trivial.c,v 1.12 2003/10/25 00:49:13 sam 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 *****************************************************************************/
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_description( _("audio filter for trivial channel mixing") );
47 set_capability( "audio filter", 1 );
48 set_callbacks( Create, NULL );
51 /*****************************************************************************
52 * Create: allocate trivial channel mixer
53 *****************************************************************************/
54 static int Create( vlc_object_t *p_this )
56 aout_filter_t * p_filter = (aout_filter_t *)p_this;
58 if ( (p_filter->input.i_physical_channels
59 == p_filter->output.i_physical_channels
60 && p_filter->input.i_original_channels
61 == p_filter->output.i_original_channels)
62 || p_filter->input.i_format != p_filter->output.i_format
63 || p_filter->input.i_rate != p_filter->output.i_rate
64 || (p_filter->input.i_format != VLC_FOURCC('f','l','3','2')
65 && p_filter->input.i_format != VLC_FOURCC('f','i','3','2')) )
70 p_filter->pf_do_work = DoWork;
71 if ( aout_FormatNbChannels( &p_filter->input )
72 > aout_FormatNbChannels( &p_filter->output ) )
75 p_filter->b_in_place = 1;
80 p_filter->b_in_place = 0;
86 /*****************************************************************************
87 * SparseCopy: trivially downmix or upmix a buffer
88 *****************************************************************************/
89 static void SparseCopy( int32_t * p_dest, const int32_t * p_src, size_t i_len,
90 int i_output_stride, int i_input_stride )
93 for ( i = i_len; i--; )
96 for ( j = 0; j < i_output_stride; j++ )
98 p_dest[j] = p_src[j % i_input_stride];
100 p_src += i_input_stride;
101 p_dest += i_output_stride;
105 /*****************************************************************************
106 * DoWork: convert a buffer
107 *****************************************************************************/
108 static void DoWork( aout_instance_t * p_aout, aout_filter_t * p_filter,
109 aout_buffer_t * p_in_buf, aout_buffer_t * p_out_buf )
111 int i_input_nb = aout_FormatNbChannels( &p_filter->input );
112 int i_output_nb = aout_FormatNbChannels( &p_filter->output );
113 int32_t * p_dest = (int32_t *)p_out_buf->p_buffer;
114 int32_t * p_src = (int32_t *)p_in_buf->p_buffer;
116 p_out_buf->i_nb_samples = p_in_buf->i_nb_samples;
117 p_out_buf->i_nb_bytes = p_in_buf->i_nb_bytes * i_output_nb / i_input_nb;
119 if ( (p_filter->output.i_original_channels & AOUT_CHAN_PHYSMASK)
120 != (p_filter->input.i_original_channels & AOUT_CHAN_PHYSMASK)
121 && (p_filter->input.i_original_channels & AOUT_CHAN_PHYSMASK)
122 == (AOUT_CHAN_LEFT | AOUT_CHAN_RIGHT) )
125 /* This is a bit special. */
126 if ( !(p_filter->output.i_original_channels & AOUT_CHAN_LEFT) )
130 if ( p_filter->output.i_physical_channels == AOUT_CHAN_CENTER )
133 for ( i = p_in_buf->i_nb_samples; i--; )
142 /* Fake-stereo mode */
143 for ( i = p_in_buf->i_nb_samples; i--; )
153 else if ( p_filter->output.i_original_channels
154 & AOUT_CHAN_REVERSESTEREO )
156 /* Reverse-stereo mode */
158 for ( i = p_in_buf->i_nb_samples; i--; )
169 SparseCopy( p_dest, p_src, p_in_buf->i_nb_samples, i_output_nb,