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[vlc] / modules / audio_mixer / trivial.c
1 /*****************************************************************************
2  * trivial.c : trivial mixer plug-in (1 input, no downmixing)
3  *****************************************************************************
4  * Copyright (C) 2002 the VideoLAN team
5  * $Id$
6  *
7  * Authors: Christophe Massiot <massiot@via.ecp.fr>
8  *
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.
13  *
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.
18  *
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  *****************************************************************************/
23
24 /*****************************************************************************
25  * Preamble
26  *****************************************************************************/
27
28 #ifdef HAVE_CONFIG_H
29 # include "config.h"
30 #endif
31
32 #include <stddef.h>
33 #include <vlc_common.h>
34 #include <vlc_plugin.h>
35 #include <vlc_aout.h>
36
37 /*****************************************************************************
38  * Local prototypes
39  *****************************************************************************/
40 static int  Create    ( vlc_object_t * );
41
42 static void DoWork    ( aout_instance_t *, aout_buffer_t * );
43
44 /*****************************************************************************
45  * Module descriptor
46  *****************************************************************************/
47 vlc_module_begin();
48     set_category( CAT_AUDIO );
49     set_subcategory( SUBCAT_AUDIO_MISC );
50     set_description( N_("Trivial audio mixer") );
51     set_capability( "audio mixer", 1 );
52     set_callbacks( Create, NULL );
53 vlc_module_end();
54
55 /*****************************************************************************
56  * Create: allocate trivial mixer
57  *****************************************************************************/
58 static int Create( vlc_object_t *p_this )
59 {
60     aout_instance_t * p_aout = (aout_instance_t *)p_this;
61
62     if ( p_aout->mixer.mixer.i_format != VLC_FOURCC('f','l','3','2')
63           && p_aout->mixer.mixer.i_format != VLC_FOURCC('f','i','3','2') )
64     {
65         return -1;
66     }
67
68     p_aout->mixer.pf_do_work = DoWork;
69
70     return 0;
71 }
72
73 /*****************************************************************************
74  * DoWork: mix a new output buffer
75  *****************************************************************************/
76 static void DoWork( aout_instance_t * p_aout, aout_buffer_t * p_buffer )
77 {
78     int i = 0;
79     aout_input_t * p_input = p_aout->pp_inputs[i];
80     int i_nb_channels = aout_FormatNbChannels( &p_aout->mixer.mixer );
81     int i_nb_bytes = p_buffer->i_nb_samples * sizeof(int32_t)
82                       * i_nb_channels;
83     uint8_t * p_in;
84     uint8_t * p_out;
85
86     while ( p_input->b_error )
87     {
88         p_input = p_aout->pp_inputs[++i];
89         /* This can't crash because if no input has b_error == 0, the
90          * audio mixer cannot run and we can't be here. */
91     }
92     p_in = p_input->p_first_byte_to_mix;
93     p_out = p_buffer->p_buffer;
94
95     for ( ; ; )
96     {
97         ptrdiff_t i_available_bytes = (p_input->fifo.p_first->p_buffer
98                                         - p_in)
99                                         + p_input->fifo.p_first->i_nb_samples
100                                            * sizeof(int32_t)
101                                            * i_nb_channels;
102
103         if ( i_available_bytes < i_nb_bytes )
104         {
105             aout_buffer_t * p_old_buffer;
106
107             vlc_memcpy( p_out, p_in, i_available_bytes );
108             i_nb_bytes -= i_available_bytes;
109             p_out += i_available_bytes;
110
111             /* Next buffer */
112             p_old_buffer = aout_FifoPop( p_aout, &p_input->fifo );
113             aout_BufferFree( p_old_buffer );
114             if ( p_input->fifo.p_first == NULL )
115             {
116                 msg_Err( p_aout, "internal amix error" );
117                 return;
118             }
119             p_in = p_input->fifo.p_first->p_buffer;
120         }
121         else
122         {
123             vlc_memcpy( p_out, p_in, i_nb_bytes );
124             p_input->p_first_byte_to_mix = p_in + i_nb_bytes;
125             break;
126         }
127     }
128
129     /* Empty other FIFOs to avoid a memory leak. */
130     for ( i++; i < p_aout->i_nb_inputs; i++ )
131     {
132         aout_fifo_t * p_fifo;
133         aout_buffer_t * p_deleted;
134
135         p_input = p_aout->pp_inputs[i];
136         if ( p_input->b_error ) continue;
137         p_fifo = &p_input->fifo;
138         p_deleted = p_fifo->p_first;
139         while ( p_deleted != NULL )
140         {
141             aout_buffer_t * p_next = p_deleted->p_next;
142             aout_BufferFree( p_deleted );
143             p_deleted = p_next;
144         }
145         p_fifo->p_first = NULL;
146         p_fifo->pp_last = &p_fifo->p_first;
147     }
148 }
149