modules/demux/a52.c

   1 /*****************************************************************************
   2  * a52.c : raw A/52 stream input module for vlc
   3  *****************************************************************************
   4  * Copyright (C) 2001 the VideoLAN team
   5  * $Id$
   6  *
   7  * Authors: Gildas Bazin <gbazin@netcourrier.com>
   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 #include <vlc/vlc.h>
  28 #include <vlc/input.h>
  29 #include <vlc_codec.h>
  30
  31 #ifdef HAVE_UNISTD_H
  32 #   include <unistd.h>
  33 #endif
  34
  35 /*****************************************************************************
  36  * Module descriptor
  37  *****************************************************************************/
  38 static int  Open  ( vlc_object_t * );
  39 static void Close ( vlc_object_t * );
  40
  41 vlc_module_begin();
  42     set_category( CAT_INPUT );
  43     set_subcategory( SUBCAT_INPUT_DEMUX );
  44     set_description( _("Raw A/52 demuxer") );
  45     set_capability( "demux2", 145 );
  46     set_callbacks( Open, Close );
  47     add_shortcut( "a52" );
  48 vlc_module_end();
  49
  50 /*****************************************************************************
  51  * Local prototypes
  52  *****************************************************************************/
  53 static int Demux  ( demux_t * );
  54 static int Control( demux_t *, int, va_list );
  55
  56 struct demux_sys_t
  57 {
  58     vlc_bool_t  b_start;
  59     es_out_id_t *p_es;
  60
  61     /* Packetizer */
  62     decoder_t *p_packetizer;
  63
  64     int i_mux_rate;
  65     vlc_bool_t b_big_endian;
  66 };
  67
  68 static int CheckSync( uint8_t *p_peek, vlc_bool_t *p_big_endian );
  69
  70 #define PCM_FRAME_SIZE (1536 * 4)
  71 #define A52_PACKET_SIZE (4 * PCM_FRAME_SIZE)
  72 #define A52_MAX_HEADER_SIZE 10
  73
  74
  75 /*****************************************************************************
  76  * Open: initializes ES structures
  77  *****************************************************************************/
  78 static int Open( vlc_object_t * p_this )
  79 {
  80     demux_t     *p_demux = (demux_t*)p_this;
  81     demux_sys_t *p_sys;
  82     byte_t      *p_peek;
  83     int         i_peek = 0;
  84     vlc_bool_t  b_big_endian = 0; /* Arbitrary initialisation */
  85
  86     /* Check if we are dealing with a WAV file */
  87     if( stream_Peek( p_demux->s, &p_peek, 12 ) == 12 &&
  88         !memcmp( p_peek, "RIFF", 4 ) && !memcmp( p_peek + 8, "WAVE", 4 ) )
  89     {
  90         int i_size;
  91
  92         /* Skip the wave header */
  93         i_peek = 12 + 8;
  94         while( stream_Peek( p_demux->s, &p_peek, i_peek ) == i_peek &&
  95                memcmp( p_peek + i_peek - 8, "data", 4 ) )
  96         {
  97             i_peek += GetDWLE( p_peek + i_peek - 4 ) + 8;
  98         }
  99
 100         /* TODO: should check wave format and sample_rate */
 101
 102         /* Some A52 wav files don't begin with a sync code so we do a more
 103          * extensive search */
 104         i_size = stream_Peek( p_demux->s, &p_peek, i_peek + A52_PACKET_SIZE * 2);
 105         i_size -= (PCM_FRAME_SIZE + A52_MAX_HEADER_SIZE);
 106
 107         while( i_peek < i_size )
 108         {
 109             if( CheckSync( p_peek + i_peek, &b_big_endian ) != VLC_SUCCESS )
 110                 /* The data is stored in 16 bits words */
 111                 i_peek += 2;
 112             else
 113             {
 114                 /* Check following sync code */
 115                 if( CheckSync( p_peek + i_peek + PCM_FRAME_SIZE,
 116                                &b_big_endian ) != VLC_SUCCESS )
 117                 {
 118                     i_peek += 2;
 119                     continue;
 120                 }
 121
 122                 break;
 123             }
 124         }
 125     }
 126
 127     /* Have a peep at the show. */
 128     if( stream_Peek( p_demux->s, &p_peek, i_peek + A52_MAX_HEADER_SIZE * 2 ) <
 129         i_peek + A52_MAX_HEADER_SIZE * 2 )
 130     {
 131         /* Stream too short */
 132         msg_Warn( p_demux, "cannot peek()" );
 133         return VLC_EGENERIC;
 134     }
 135
 136     if( CheckSync( p_peek + i_peek, &b_big_endian ) != VLC_SUCCESS )
 137     {
 138         if( strncmp( p_demux->psz_demux, "a52", 3 ) )
 139         {
 140             return VLC_EGENERIC;
 141         }
 142
 143         /* User forced */
 144         msg_Err( p_demux, "this doesn't look like a A52 audio stream, "
 145                  "continuing anyway" );
 146     }
 147
 148     /* Fill p_demux fields */
 149     p_demux->pf_demux = Demux;
 150     p_demux->pf_control = Control;
 151     p_demux->p_sys = p_sys = malloc( sizeof( demux_sys_t ) );
 152     p_sys->b_start = VLC_TRUE;
 153     p_sys->i_mux_rate = 0;
 154     p_sys->b_big_endian = b_big_endian;
 155
 156     /*
 157      * Load the A52 packetizer
 158      */
 159     p_sys->p_packetizer = vlc_object_create( p_demux, VLC_OBJECT_DECODER );
 160     p_sys->p_packetizer->pf_decode_audio = 0;
 161     p_sys->p_packetizer->pf_decode_video = 0;
 162     p_sys->p_packetizer->pf_decode_sub = 0;
 163     p_sys->p_packetizer->pf_packetize = 0;
 164
 165     /* Initialization of decoder structure */
 166     es_format_Init( &p_sys->p_packetizer->fmt_in, AUDIO_ES,
 167                     VLC_FOURCC( 'a', '5', '2', ' ' ) );
 168
 169     p_sys->p_packetizer->p_module =
 170         module_Need( p_sys->p_packetizer, "packetizer", NULL, 0 );
 171     if( !p_sys->p_packetizer->p_module )
 172     {
 173         msg_Err( p_demux, "cannot find A52 packetizer" );
 174         return VLC_EGENERIC;
 175     }
 176
 177     /* Create one program */
 178     p_sys->p_es = es_out_Add( p_demux->out, &p_sys->p_packetizer->fmt_in );
 179
 180     return VLC_SUCCESS;
 181 }
 182
 183 /*****************************************************************************
 184  * Close: frees unused data
 185  *****************************************************************************/
 186 static void Close( vlc_object_t * p_this )
 187 {
 188     demux_t        *p_demux = (demux_t*)p_this;
 189     demux_sys_t    *p_sys = p_demux->p_sys;
 190
 191     /* Unneed module */
 192     module_Unneed( p_sys->p_packetizer, p_sys->p_packetizer->p_module );
 193
 194     /* Delete the decoder */
 195     vlc_object_destroy( p_sys->p_packetizer );
 196
 197     free( p_sys );
 198 }
 199
 200 /*****************************************************************************
 201  * Demux: reads and demuxes data packets
 202  *****************************************************************************
 203  * Returns -1 in case of error, 0 in case of EOF, 1 otherwise
 204  *****************************************************************************/
 205 static int Demux( demux_t *p_demux )
 206 {
 207     demux_sys_t *p_sys = p_demux->p_sys;
 208     block_t     *p_block_in, *p_block_out;
 209
 210      /* Align stream */
 211     int64_t i_pos = stream_Tell( p_demux->s );
 212     if( i_pos % 2 ) stream_Read( p_demux->s, NULL, 1 );
 213
 214     if( !( p_block_in = stream_Block( p_demux->s, A52_PACKET_SIZE ) ) )
 215     {
 216         return 0;
 217     }
 218
 219     if( !p_sys->b_big_endian && p_block_in->i_buffer )
 220     {
 221         /* Convert to big endian */
 222
 223 #ifdef HAVE_SWAB
 224         swab(p_block_in->p_buffer, p_block_in->p_buffer, p_block_in->i_buffer);
 225
 226 #else
 227         int i;
 228         byte_t *p_tmp, tmp;
 229         p_tmp = p_block_in->p_buffer;
 230         for( i = p_block_in->i_buffer / 2 ; i-- ; )
 231         {
 232             tmp = p_tmp[0];
 233             p_tmp[0] = p_tmp[1];
 234             p_tmp[1] = tmp;
 235             p_tmp += 2;
 236         }
 237 #endif
 238     }
 239
 240     if( p_sys->b_start )
 241         p_block_in->i_pts = p_block_in->i_dts = 1;
 242     else
 243         p_block_in->i_pts = p_block_in->i_dts = 0;
 244
 245     while( (p_block_out = p_sys->p_packetizer->pf_packetize(
 246                 p_sys->p_packetizer, &p_block_in )) )
 247     {
 248         p_sys->b_start = VLC_FALSE;
 249
 250         while( p_block_out )
 251         {
 252             block_t *p_next = p_block_out->p_next;
 253
 254             /* We assume a constant bitrate */
 255             if( p_block_out->i_length )
 256             {
 257                 p_sys->i_mux_rate =
 258                     p_block_out->i_buffer * I64C(1000000)/p_block_out->i_length;
 259             }
 260
 261             /* set PCR */
 262             es_out_Control( p_demux->out, ES_OUT_SET_PCR, p_block_out->i_dts );
 263
 264             es_out_Send( p_demux->out, p_sys->p_es, p_block_out );
 265
 266             p_block_out = p_next;
 267         }
 268     }
 269
 270     return 1;
 271 }
 272
 273 /*****************************************************************************
 274  * Control:
 275  *****************************************************************************/
 276 static int Control( demux_t *p_demux, int i_query, va_list args )
 277 {
 278     demux_sys_t *p_sys  = p_demux->p_sys;
 279     if( i_query == DEMUX_SET_TIME )
 280         return VLC_EGENERIC;
 281     else
 282         return demux2_vaControlHelper( p_demux->s,
 283                                        0, -1,
 284                                        8*p_sys->i_mux_rate, 1, i_query, args );
 285 }
 286
 287 /*****************************************************************************
 288  * CheckSync: Check if buffer starts with an A52 sync code
 289  *****************************************************************************/
 290 static int CheckSync( uint8_t *p_peek, vlc_bool_t *p_big_endian )
 291 {
 292     /* Little endian version of the bitstream */
 293     if( p_peek[0] == 0x77 && p_peek[1] == 0x0b &&
 294         p_peek[4] < 0x60 /* bsid < 12 */ )
 295     {
 296         *p_big_endian = VLC_FALSE;
 297         return VLC_SUCCESS;
 298     }
 299     /* Big endian version of the bitstream */
 300     else if( p_peek[0] == 0x0b && p_peek[1] == 0x77 &&
 301              p_peek[5] < 0x60 /* bsid < 12 */ )
 302     {
 303         *p_big_endian = VLC_TRUE;
 304         return VLC_SUCCESS;
 305     }
 306
 307     return VLC_EGENERIC;
 308 }
 309
 310