1 /*****************************************************************************
2 * a52tospdif.c : encapsulates A/52 frames into S/PDIF packets
3 *****************************************************************************
4 * Copyright (C) 2002, 2006 the VideoLAN team
7 * Authors: Christophe Massiot <massiot@via.ecp.fr>
8 * Stéphane Borel <stef@via.ecp.fr>
10 * This program is free software; you can redistribute it and/or modify
11 * it under the terms of the GNU General Public License as published by
12 * the Free Software Foundation; either version 2 of the License, or
13 * (at your option) any later version.
15 * This program is distributed in the hope that it will be useful,
16 * but WITHOUT ANY WARRANTY; without even the implied warranty of
17 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
18 * GNU General Public License for more details.
20 * You should have received a copy of the GNU General Public License
21 * along with this program; if not, write to the Free Software
22 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston MA 02110-1301, USA.
23 *****************************************************************************/
25 /*****************************************************************************
27 *****************************************************************************/
37 /*****************************************************************************
39 *****************************************************************************/
40 static int Create ( vlc_object_t * );
41 static void DoWork ( 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 A/52->S/PDIF encapsulation") );
51 set_capability( "audio filter", 10 );
52 set_callbacks( Create, NULL );
55 /*****************************************************************************
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_format != VLC_FOURCC('a','5','2',' ') ||
63 ( p_filter->output.i_format != VLC_FOURCC('s','p','d','b') &&
64 p_filter->output.i_format != VLC_FOURCC('s','p','d','i') ) )
69 p_filter->pf_do_work = DoWork;
70 p_filter->b_in_place = 0;
75 /*****************************************************************************
76 * DoWork: convert a buffer
77 *****************************************************************************/
78 static void DoWork( aout_instance_t * p_aout, aout_filter_t * p_filter,
79 aout_buffer_t * p_in_buf, aout_buffer_t * p_out_buf )
81 /* AC3 is natively big endian. Most SPDIF devices have the native
82 * endianness of the computer system.
83 * On Mac OS X however, little endian devices are also common.
85 static const uint8_t p_sync_le[6] = { 0x72, 0xF8, 0x1F, 0x4E, 0x01, 0x00 };
86 static const uint8_t p_sync_be[6] = { 0xF8, 0x72, 0x4E, 0x1F, 0x00, 0x01 };
91 uint16_t i_frame_size = p_in_buf->i_nb_bytes / 2;
92 byte_t * p_in = p_in_buf->p_buffer;
93 byte_t * p_out = p_out_buf->p_buffer;
95 /* Copy the S/PDIF headers. */
96 if( p_filter->output.i_format == VLC_FOURCC('s','p','d','b') )
98 p_filter->p_libvlc->pf_memcpy( p_out, p_sync_be, 6 );
99 p_out[4] = p_in[5] & 0x7; /* bsmod */
100 p_out[6] = (i_frame_size >> 4) & 0xff;
101 p_out[7] = (i_frame_size << 4) & 0xff;
102 p_filter->p_libvlc->pf_memcpy( &p_out[8], p_in, i_frame_size * 2 );
106 p_filter->p_libvlc->pf_memcpy( p_out, p_sync_le, 6 );
107 p_out[5] = p_in[5] & 0x7; /* bsmod */
108 p_out[6] = (i_frame_size << 4) & 0xff;
109 p_out[7] = (i_frame_size >> 4) & 0xff;
111 swab( p_in, &p_out[8], i_frame_size * 2 );
114 for( i = i_frame_size; i-- ; )
118 p_tmp += 2; p_in += 2;
122 p_filter->p_libvlc->pf_memset( p_out + 8 + i_frame_size * 2, 0,
123 AOUT_SPDIF_SIZE - i_frame_size * 2 - 8 );
125 p_out_buf->i_nb_samples = p_in_buf->i_nb_samples;
126 p_out_buf->i_nb_bytes = AOUT_SPDIF_SIZE;