1 /*****************************************************************************
2 * trivial.c : trivial channel mixer plug-in (drops unwanted channels)
3 *****************************************************************************
4 * Copyright (C) 2002, 2006 the VideoLAN team
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., 51 Franklin Street, Fifth Floor, Boston MA 02110-1301, USA.
22 *****************************************************************************/
24 /*****************************************************************************
26 *****************************************************************************/
32 #include <vlc_common.h>
33 #include <vlc_plugin.h>
36 /*****************************************************************************
38 *****************************************************************************/
39 static int Create ( vlc_object_t * );
41 static void DoWork ( aout_instance_t *, aout_filter_t *, aout_buffer_t *,
44 /*****************************************************************************
46 *****************************************************************************/
48 set_description( N_("Audio filter for trivial channel mixing") )
49 set_capability( "audio filter", 1 )
50 set_category( CAT_AUDIO )
51 set_subcategory( SUBCAT_AUDIO_MISC )
52 set_callbacks( Create, NULL )
55 /*****************************************************************************
56 * Create: allocate trivial channel mixer
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_physical_channels
63 == p_filter->output.i_physical_channels
64 && p_filter->input.i_original_channels
65 == p_filter->output.i_original_channels)
66 || p_filter->input.i_format != p_filter->output.i_format
67 || p_filter->input.i_rate != p_filter->output.i_rate
68 || (p_filter->input.i_format != VLC_FOURCC('f','l','3','2')
69 && p_filter->input.i_format != VLC_FOURCC('f','i','3','2')) )
74 p_filter->pf_do_work = DoWork;
75 if ( aout_FormatNbChannels( &p_filter->input )
76 > aout_FormatNbChannels( &p_filter->output ) )
79 p_filter->b_in_place = 1;
84 p_filter->b_in_place = 0;
90 /*****************************************************************************
91 * SparseCopy: trivially downmix or upmix a buffer
92 *****************************************************************************/
93 static void SparseCopy( int32_t * p_dest, const int32_t * p_src, size_t i_len,
94 int i_output_stride, int i_input_stride )
97 for ( i = i_len; i--; )
100 for ( j = 0; j < i_output_stride; j++ )
102 p_dest[j] = p_src[j % i_input_stride];
104 p_src += i_input_stride;
105 p_dest += i_output_stride;
109 /*****************************************************************************
110 * DoWork: convert a buffer
111 *****************************************************************************/
112 static void DoWork( aout_instance_t * p_aout, aout_filter_t * p_filter,
113 aout_buffer_t * p_in_buf, aout_buffer_t * p_out_buf )
116 int i_input_nb = aout_FormatNbChannels( &p_filter->input );
117 int i_output_nb = aout_FormatNbChannels( &p_filter->output );
118 int32_t * p_dest = (int32_t *)p_out_buf->p_buffer;
119 int32_t * p_src = (int32_t *)p_in_buf->p_buffer;
121 p_out_buf->i_nb_samples = p_in_buf->i_nb_samples;
122 p_out_buf->i_nb_bytes = p_in_buf->i_nb_bytes * i_output_nb / i_input_nb;
124 if ( (p_filter->output.i_original_channels & AOUT_CHAN_PHYSMASK)
125 != (p_filter->input.i_original_channels & AOUT_CHAN_PHYSMASK)
126 && (p_filter->input.i_original_channels & AOUT_CHAN_PHYSMASK)
127 == (AOUT_CHAN_LEFT | AOUT_CHAN_RIGHT) )
130 /* This is a bit special. */
131 if ( !(p_filter->output.i_original_channels & AOUT_CHAN_LEFT) )
135 if ( p_filter->output.i_physical_channels == AOUT_CHAN_CENTER )
138 for ( i = p_in_buf->i_nb_samples; i--; )
147 /* Fake-stereo mode */
148 for ( i = p_in_buf->i_nb_samples; i--; )
158 else if ( p_filter->output.i_original_channels
159 & AOUT_CHAN_REVERSESTEREO )
161 /* Reverse-stereo mode */
163 for ( i = p_in_buf->i_nb_samples; i--; )
174 SparseCopy( p_dest, p_src, p_in_buf->i_nb_samples, i_output_nb,