1 /*****************************************************************************
2 * a52.c: A/52 basic parser
3 *****************************************************************************
4 * Copyright (C) 2001-2002 VideoLAN
5 * $Id: a52.c,v 1.10 2002/09/06 23:15:44 massiot Exp $
7 * Authors: Stéphane Borel <stef@via.ecp.fr>
8 * Christophe Massiot <massiot@via.ecp.fr>
9 * Michel Lespinasse <walken@zoy.org>
10 * Aaron Holtzman <aholtzma@ess.engr.uvic.ca>
12 * This program is free software; you can redistribute it and/or modify
13 * it under the terms of the GNU General Public License as published by
14 * the Free Software Foundation; either version 2 of the License, or
15 * (at your option) any later version.
17 * This program is distributed in the hope that it will be useful,
18 * but WITHOUT ANY WARRANTY; without even the implied warranty of
19 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
20 * GNU General Public License for more details.
22 * You should have received a copy of the GNU General Public License
23 * along with this program; if not, write to the Free Software
24 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111, USA.
25 *****************************************************************************/
27 /*****************************************************************************
29 *****************************************************************************/
32 #include <string.h> /* memcpy() */
36 #include <vlc/decoder.h>
43 #define A52_FRAME_NB 1536
45 /*****************************************************************************
46 * spdif_thread_t : A52 pass-through thread descriptor
47 *****************************************************************************/
48 typedef struct spdif_thread_s
53 vlc_thread_t thread_id; /* id for thread functions */
58 decoder_fifo_t * p_fifo; /* stores the PES stream data */
60 /* The bit stream structure handles the PES stream at the bit level */
61 bit_stream_t bit_stream;
66 aout_instance_t * p_aout; /* opaque */
67 aout_input_t * p_aout_input; /* opaque */
68 audio_sample_format_t output_format;
71 /****************************************************************************
73 ****************************************************************************/
74 static int OpenDecoder ( vlc_object_t * );
75 static int RunDecoder ( decoder_fifo_t * );
77 static int InitThread ( spdif_thread_t *, decoder_fifo_t * );
78 static void EndThread ( spdif_thread_t * );
80 static int SyncInfo ( const byte_t *, int *, int *, int * );
82 /*****************************************************************************
84 *****************************************************************************/
86 set_description( _("A/52 parser") );
87 set_capability( "decoder", 0 );
88 set_callbacks( OpenDecoder, NULL );
89 add_shortcut( "pass_through" );
90 add_shortcut( "pass" );
93 /*****************************************************************************
94 * OpenDecoder: probe the decoder and return score
95 *****************************************************************************
96 * Tries to launch a decoder and return score so that the interface is able
98 *****************************************************************************/
99 static int OpenDecoder( vlc_object_t *p_this )
101 decoder_fifo_t *p_fifo = (decoder_fifo_t*) p_this;
103 if( p_fifo->i_fourcc != VLC_FOURCC('a','5','2',' ')
104 && p_fifo->i_fourcc != VLC_FOURCC('a','5','2','b') )
109 p_fifo->pf_run = RunDecoder;
113 /****************************************************************************
114 * RunDecoder: the whole thing
115 ****************************************************************************
116 * This function is called just after the thread is launched.
117 ****************************************************************************/
118 static int RunDecoder( decoder_fifo_t *p_fifo )
120 spdif_thread_t * p_dec;
121 audio_date_t end_date;
123 /* Allocate the memory needed to store the thread's structure */
124 p_dec = malloc( sizeof(spdif_thread_t) );
127 msg_Err( p_fifo, "out of memory" );
128 DecoderError( p_fifo );
132 if ( InitThread( p_dec, p_fifo ) )
135 msg_Err( p_fifo, "could not initialize thread" );
136 DecoderError( p_fifo );
141 /* decoder thread's main loop */
142 while ( !p_dec->p_fifo->b_die && !p_dec->p_fifo->b_error )
144 int i_frame_size, i_channels, i_rate, i_bit_rate;
146 /* Temporary buffer to store the raw frame to be decoded */
148 aout_buffer_t * p_buffer;
150 /* Look for sync word - should be 0x0b77 */
151 RealignBits( &p_dec->bit_stream );
152 while ( (ShowBits( &p_dec->bit_stream, 16 ) ) != 0x0b77 &&
153 (!p_dec->p_fifo->b_die) && (!p_dec->p_fifo->b_error))
155 RemoveBits( &p_dec->bit_stream, 8 );
158 /* Set the Presentation Time Stamp */
159 NextPTS( &p_dec->bit_stream, &pts, NULL );
160 if ( pts != 0 && pts != aout_DateGet( &end_date ) )
162 aout_DateSet( &end_date, pts );
165 /* Get A/52 frame header */
166 GetChunk( &p_dec->bit_stream, p_header, 7 );
167 if( p_dec->p_fifo->b_die ) break;
169 /* Check if frame is valid and get frame info */
170 i_frame_size = SyncInfo( p_header, &i_channels, &i_rate,
175 msg_Warn( p_dec->p_fifo, "a52_syncinfo failed" );
179 if( (p_dec->p_aout_input != NULL) &&
180 ( (p_dec->output_format.i_rate != i_rate)
181 || (p_dec->output_format.i_channels != i_channels)
182 || (p_dec->output_format.i_bytes_per_frame != i_frame_size) ) )
184 /* Parameters changed - this should not happen. */
185 aout_InputDelete( p_dec->p_aout, p_dec->p_aout_input );
186 p_dec->p_aout_input = NULL;
189 /* Creating the audio input if not created yet. */
190 if( p_dec->p_aout_input == NULL )
192 p_dec->output_format.i_rate = i_rate;
193 p_dec->output_format.i_channels = i_channels;
194 p_dec->output_format.i_bytes_per_frame = i_frame_size;
195 p_dec->output_format.i_frame_length = A52_FRAME_NB;
196 aout_DateInit( &end_date, i_rate );
197 p_dec->p_aout_input = aout_InputNew( p_dec->p_fifo,
199 &p_dec->output_format );
201 if ( p_dec->p_aout_input == NULL )
203 p_dec->p_fifo->b_error = 1;
208 if ( !aout_DateGet( &end_date ) )
212 /* We've just started the stream, wait for the first PTS. */
213 GetChunk( &p_dec->bit_stream, p_junk, i_frame_size - 7 );
217 p_buffer = aout_BufferNew( p_dec->p_aout, p_dec->p_aout_input,
219 if ( p_buffer == NULL ) return -1;
220 p_buffer->start_date = aout_DateGet( &end_date );
221 p_buffer->end_date = aout_DateIncrement( &end_date,
224 /* Get the whole frame. */
225 memcpy( p_buffer->p_buffer, p_header, 7 );
226 GetChunk( &p_dec->bit_stream, p_buffer->p_buffer + 7,
228 if( p_dec->p_fifo->b_die )
230 aout_BufferDelete( p_dec->p_aout, p_dec->p_aout_input,
235 /* Send the buffer to the mixer. */
236 aout_BufferPlay( p_dec->p_aout, p_dec->p_aout_input, p_buffer );
239 /* If b_error is set, the spdif thread enters the error loop */
240 if( p_dec->p_fifo->b_error )
242 DecoderError( p_dec->p_fifo );
245 /* End of the spdif decoder thread */
251 /****************************************************************************
252 * InitThread: initialize thread data and create output fifo
253 ****************************************************************************/
254 static int InitThread( spdif_thread_t * p_dec, decoder_fifo_t * p_fifo )
256 /* Initialize the thread properties */
257 p_dec->p_aout = NULL;
258 p_dec->p_aout_input = NULL;
259 p_dec->p_fifo = p_fifo;
260 p_dec->output_format.i_format = AOUT_FMT_A52;
262 /* Init the Bitstream */
263 InitBitstream( &p_dec->bit_stream, p_dec->p_fifo,
269 /*****************************************************************************
270 * EndThread : spdif thread destruction
271 *****************************************************************************/
272 static void EndThread( spdif_thread_t * p_dec )
274 if ( p_dec->p_aout_input != NULL )
276 aout_InputDelete( p_dec->p_aout, p_dec->p_aout_input );
282 /****************************************************************************
283 * SyncInfo: parse A52 sync info
284 ****************************************************************************
285 * This code is borrowed from liba52 by Aaron Holtzman & Michel Lespinasse,
286 * since we don't want to oblige S/PDIF people to use liba52 just to get
288 ****************************************************************************/
289 int SyncInfo( const byte_t * p_buf, int * pi_channels, int * pi_sample_rate,
292 static const u8 halfrate[12] = {0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 2, 3};
293 static const int rate[] = { 32, 40, 48, 56, 64, 80, 96, 112,
294 128, 160, 192, 224, 256, 320, 384, 448,
296 static const u8 lfeon[8] = {0x10, 0x10, 0x04, 0x04, 0x04, 0x01, 0x04, 0x01};
302 if ((p_buf[0] != 0x0b) || (p_buf[1] != 0x77)) /* syncword */
305 if (p_buf[5] >= 0x60) /* bsid >= 12 */
307 half = halfrate[p_buf[5] >> 3];
309 /* acmod, dsurmod and lfeon */
310 acmod = p_buf[6] >> 5;
311 if ( p_buf[6] & 0xf8 )
313 *pi_channels = AOUT_CHAN_DOLBY;
315 else switch ( acmod )
317 case 0x0: *pi_channels = AOUT_CHAN_CHANNEL; break;
318 case 0x1: *pi_channels = AOUT_CHAN_MONO; break;
319 case 0x2: *pi_channels = AOUT_CHAN_STEREO; break;
320 case 0x3: *pi_channels = AOUT_CHAN_3F; break;
321 case 0x4: *pi_channels = AOUT_CHAN_2F1R; break;
322 case 0x5: *pi_channels = AOUT_CHAN_3F1R; break;
323 case 0x6: *pi_channels = AOUT_CHAN_2F2R; break;
324 case 0x7: *pi_channels = AOUT_CHAN_3F2R; break;
325 case 0x8: *pi_channels = AOUT_CHAN_CHANNEL1; break;
326 case 0x9: *pi_channels = AOUT_CHAN_CHANNEL2; break;
329 if ( p_buf[6] & lfeon[acmod] ) *pi_channels |= AOUT_CHAN_LFE;
331 frmsizecod = p_buf[4] & 63;
332 if (frmsizecod >= 38)
334 bitrate = rate [frmsizecod >> 1];
335 *pi_bit_rate = (bitrate * 1000) >> half;
337 switch (p_buf[4] & 0xc0) {
339 *pi_sample_rate = 48000 >> half;
342 *pi_sample_rate = 44100 >> half;
343 return 2 * (320 * bitrate / 147 + (frmsizecod & 1));
345 *pi_sample_rate = 32000 >> half;