mpeg_audio: signed integer overflow
[vlc.git] / modules / codec / mpeg_audio.c
1 /*****************************************************************************
2  * mpeg_audio.c: parse MPEG audio sync info and packetize the stream
3  *****************************************************************************
4  * Copyright (C) 2001-2003 VLC authors and VideoLAN
5  * $Id$
6  *
7  * Authors: Laurent Aimar <fenrir@via.ecp.fr>
8  *          Eric Petit <titer@videolan.org>
9  *          Christophe Massiot <massiot@via.ecp.fr>
10  *          Gildas Bazin <gbazin@videolan.org>
11  *
12  * This program is free software; you can redistribute it and/or modify it
13  * under the terms of the GNU Lesser General Public License as published by
14  * the Free Software Foundation; either version 2.1 of the License, or
15  * (at your option) any later version.
16  *
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 Lesser General Public License for more details.
21  *
22  * You should have received a copy of the GNU Lesser General Public License
23  * along with this program; if not, write to the Free Software Foundation,
24  * Inc., 51 Franklin Street, Fifth Floor, Boston MA 02110-1301, USA.
25  *****************************************************************************/
26
27 /*****************************************************************************
28  * Preamble
29  *****************************************************************************/
30 #ifdef HAVE_CONFIG_H
31 # include "config.h"
32 #endif
33
34 #include <vlc_common.h>
35 #include <vlc_plugin.h>
36 #include <vlc_codec.h>
37 #include <vlc_aout.h>
38 #include <vlc_modules.h>
39 #include <assert.h>
40
41 #include <vlc_block_helper.h>
42
43 #include "../packetizer/packetizer_helper.h"
44
45 /*****************************************************************************
46  * decoder_sys_t : decoder descriptor
47  *****************************************************************************/
48 struct decoder_sys_t
49 {
50     /* Module mode */
51     bool b_packetizer;
52
53     /*
54      * Input properties
55      */
56     int        i_state;
57
58     block_bytestream_t bytestream;
59
60     /*
61      * Common properties
62      */
63     date_t          end_date;
64     unsigned int    i_current_layer;
65
66     mtime_t i_pts;
67
68     int i_frame_size, i_free_frame_size;
69     unsigned int i_channels_conf, i_channels;
70     unsigned int i_rate, i_max_frame_size, i_frame_length;
71     unsigned int i_layer, i_bit_rate;
72
73     bool   b_discontinuity;
74 };
75
76 /* This isn't the place to put mad-specific stuff. However, it makes the
77  * mad plug-in's life much easier if we put 8 extra bytes at the end of the
78  * buffer, because that way it doesn't have to copy the block_t to a bigger
79  * buffer. This has no implication on other plug-ins, and we only lose 8 bytes
80  * per frame. --Meuuh */
81 #define MAD_BUFFER_GUARD 8
82 #define MPGA_HEADER_SIZE 4
83
84 /****************************************************************************
85  * Local prototypes
86  ****************************************************************************/
87 static int  OpenDecoder   ( vlc_object_t * );
88 static int  OpenPacketizer( vlc_object_t * );
89 static void CloseDecoder  ( vlc_object_t * );
90 static block_t *DecodeBlock  ( decoder_t *, block_t ** );
91
92 static uint8_t *GetOutBuffer ( decoder_t *, block_t ** );
93 static block_t *GetAoutBuffer( decoder_t * );
94 static block_t *GetSoutBuffer( decoder_t * );
95
96 static int SyncInfo( uint32_t i_header, unsigned int * pi_channels,
97                      unsigned int * pi_channels_conf,
98                      unsigned int * pi_sample_rate, unsigned int * pi_bit_rate,
99                      unsigned int * pi_frame_length,
100                      unsigned int * pi_max_frame_size,
101                      unsigned int * pi_layer );
102
103 /*****************************************************************************
104  * Module descriptor
105  *****************************************************************************/
106 vlc_module_begin ()
107     set_description( N_("MPEG audio layer I/II/III decoder") )
108     set_category( CAT_INPUT )
109     set_subcategory( SUBCAT_INPUT_ACODEC )
110     set_capability( "decoder", 100 )
111     set_callbacks( OpenDecoder, CloseDecoder )
112
113     add_submodule ()
114     set_description( N_("MPEG audio layer I/II/III packetizer") )
115     set_capability( "packetizer", 10 )
116     set_callbacks( OpenPacketizer, CloseDecoder )
117 vlc_module_end ()
118
119 /*****************************************************************************
120  * Open: probe the decoder and return score
121  *****************************************************************************/
122 static int Open( vlc_object_t *p_this )
123 {
124     decoder_t *p_dec = (decoder_t*)p_this;
125     decoder_sys_t *p_sys;
126
127     if(( p_dec->fmt_in.i_codec != VLC_CODEC_MPGA ) &&
128        ( p_dec->fmt_in.i_codec != VLC_CODEC_MP3 ) )
129     {
130         return VLC_EGENERIC;
131     }
132
133     /* Allocate the memory needed to store the decoder's structure */
134     if( ( p_dec->p_sys = p_sys =
135           (decoder_sys_t *)malloc(sizeof(decoder_sys_t)) ) == NULL )
136         return VLC_ENOMEM;
137
138     /* Misc init */
139     p_sys->b_packetizer = false;
140     p_sys->i_state = STATE_NOSYNC;
141     date_Set( &p_sys->end_date, 0 );
142     block_BytestreamInit( &p_sys->bytestream );
143     p_sys->i_pts = VLC_TS_INVALID;
144     p_sys->b_discontinuity = false;
145
146     /* Set output properties */
147     p_dec->fmt_out.i_cat = AUDIO_ES;
148     p_dec->fmt_out.i_codec = VLC_CODEC_MPGA;
149     p_dec->fmt_out.audio.i_rate = 0; /* So end_date gets initialized */
150
151     /* Set callback */
152     p_dec->pf_decode_audio = DecodeBlock;
153     p_dec->pf_packetize    = DecodeBlock;
154
155     /* Start with the minimum size for a free bitrate frame */
156     p_sys->i_free_frame_size = MPGA_HEADER_SIZE;
157
158     return VLC_SUCCESS;
159 }
160
161 static int OpenDecoder( vlc_object_t *p_this )
162 {
163     /* HACK: Don't use this codec if we don't have an mpga audio filter */
164     if( !module_exists( "mpgatofixed32" ) )
165         return VLC_EGENERIC;
166
167     return Open( p_this );
168 }
169
170 static int OpenPacketizer( vlc_object_t *p_this )
171 {
172     decoder_t *p_dec = (decoder_t*)p_this;
173
174     int i_ret = Open( p_this );
175
176     if( i_ret == VLC_SUCCESS ) p_dec->p_sys->b_packetizer = true;
177
178     return i_ret;
179 }
180
181 /****************************************************************************
182  * DecodeBlock: the whole thing
183  ****************************************************************************
184  * This function is called just after the thread is launched.
185  ****************************************************************************/
186 static block_t *DecodeBlock( decoder_t *p_dec, block_t **pp_block )
187 {
188     decoder_sys_t *p_sys = p_dec->p_sys;
189     uint8_t p_header[MAD_BUFFER_GUARD];
190     uint32_t i_header;
191     uint8_t *p_buf;
192     block_t *p_out_buffer;
193
194     block_t *p_block = pp_block ? *pp_block : NULL;
195
196     if (p_block) {
197         if( p_block->i_flags&(BLOCK_FLAG_DISCONTINUITY|BLOCK_FLAG_CORRUPTED) )
198         {
199             if( p_block->i_flags&BLOCK_FLAG_CORRUPTED )
200             {
201                 p_sys->i_state = STATE_NOSYNC;
202                 block_BytestreamEmpty( &p_sys->bytestream );
203             }
204             date_Set( &p_sys->end_date, 0 );
205             block_Release( p_block );
206             p_sys->b_discontinuity = true;
207             return NULL;
208         }
209
210         if( !date_Get( &p_sys->end_date ) && p_block->i_pts <= VLC_TS_INVALID )
211         {
212             /* We've just started the stream, wait for the first PTS. */
213             msg_Dbg( p_dec, "waiting for PTS" );
214             block_Release( p_block );
215             return NULL;
216         }
217
218         block_BytestreamPush( &p_sys->bytestream, p_block );
219     } else
220         p_sys->i_state = STATE_SEND_DATA; /* return all the data we have left */
221
222     while( 1 )
223     {
224         switch( p_sys->i_state )
225         {
226
227         case STATE_NOSYNC:
228             while( block_PeekBytes( &p_sys->bytestream, p_header, 2 )
229                    == VLC_SUCCESS )
230             {
231                 /* Look for sync word - should be 0xffe */
232                 if( p_header[0] == 0xff && (p_header[1] & 0xe0) == 0xe0 )
233                 {
234                     p_sys->i_state = STATE_SYNC;
235                     break;
236                 }
237                 block_SkipByte( &p_sys->bytestream );
238             }
239             if( p_sys->i_state != STATE_SYNC )
240             {
241                 block_BytestreamFlush( &p_sys->bytestream );
242
243                 /* Need more data */
244                 return NULL;
245             }
246
247         case STATE_SYNC:
248             /* New frame, set the Presentation Time Stamp */
249             p_sys->i_pts = p_sys->bytestream.p_block->i_pts;
250             if( p_sys->i_pts > VLC_TS_INVALID &&
251                 p_sys->i_pts != date_Get( &p_sys->end_date ) )
252             {
253                 date_Set( &p_sys->end_date, p_sys->i_pts );
254             }
255             p_sys->i_state = STATE_HEADER;
256
257         case STATE_HEADER:
258             /* Get MPGA frame header (MPGA_HEADER_SIZE bytes) */
259             if( block_PeekBytes( &p_sys->bytestream, p_header,
260                                  MPGA_HEADER_SIZE ) != VLC_SUCCESS )
261             {
262                 /* Need more data */
263                 return NULL;
264             }
265
266             /* Build frame header */
267             i_header = GetDWBE(p_header);
268
269             /* Check if frame is valid and get frame info */
270             p_sys->i_frame_size = SyncInfo( i_header,
271                                             &p_sys->i_channels,
272                                             &p_sys->i_channels_conf,
273                                             &p_sys->i_rate,
274                                             &p_sys->i_bit_rate,
275                                             &p_sys->i_frame_length,
276                                             &p_sys->i_max_frame_size,
277                                             &p_sys->i_layer );
278
279             p_dec->fmt_in.i_profile = p_sys->i_layer;
280
281             if( p_sys->i_frame_size == -1 )
282             {
283                 msg_Dbg( p_dec, "emulated startcode" );
284                 block_SkipByte( &p_sys->bytestream );
285                 p_sys->i_state = STATE_NOSYNC;
286                 p_sys->b_discontinuity = true;
287                 break;
288             }
289
290             if( p_sys->i_bit_rate == 0 )
291             {
292                 /* Free bitrate, but 99% emulated startcode :( */
293                 if( p_dec->p_sys->i_free_frame_size == MPGA_HEADER_SIZE )
294                 {
295                     msg_Dbg( p_dec, "free bitrate mode");
296                 }
297                 /* The -1 below is to account for the frame padding */
298                 p_sys->i_frame_size = p_sys->i_free_frame_size - 1;
299             }
300
301             p_sys->i_state = STATE_NEXT_SYNC;
302
303         case STATE_NEXT_SYNC:
304             /* TODO: If p_block == NULL, flush the buffer without checking the
305              * next sync word */
306
307             /* Check if next expected frame contains the sync word */
308             if( block_PeekOffsetBytes( &p_sys->bytestream,
309                                        p_sys->i_frame_size, p_header,
310                                        MAD_BUFFER_GUARD ) != VLC_SUCCESS )
311             {
312                 /* Need more data */
313                 return NULL;
314             }
315
316             if( p_header[0] == 0xff && (p_header[1] & 0xe0) == 0xe0 )
317             {
318                 /* Startcode is fine, let's try the header as an extra check */
319                 int i_next_frame_size;
320                 unsigned int i_next_channels, i_next_channels_conf;
321                 unsigned int i_next_rate, i_next_bit_rate;
322                 unsigned int i_next_frame_length, i_next_max_frame_size;
323                 unsigned int i_next_layer;
324
325                 /* Build frame header */
326                 i_header = GetDWBE(p_header);
327
328                 i_next_frame_size = SyncInfo( i_header,
329                                               &i_next_channels,
330                                               &i_next_channels_conf,
331                                               &i_next_rate,
332                                               &i_next_bit_rate,
333                                               &i_next_frame_length,
334                                               &i_next_max_frame_size,
335                                               &i_next_layer );
336
337                 /* Free bitrate only */
338                 if( p_sys->i_bit_rate == 0 && i_next_frame_size == -1 )
339                 {
340                     if( (unsigned int)p_sys->i_frame_size >
341                         p_sys->i_max_frame_size )
342                     {
343                         msg_Dbg( p_dec, "frame too big %d > %d "
344                                  "(emulated startcode ?)", p_sys->i_frame_size,
345                                  p_sys->i_max_frame_size );
346                         block_SkipByte( &p_sys->bytestream );
347                         p_sys->i_state = STATE_NOSYNC;
348                         p_sys->i_free_frame_size = MPGA_HEADER_SIZE;
349                         break;
350                     }
351
352                     p_sys->i_frame_size++;
353                     break;
354                 }
355
356                 if( i_next_frame_size == -1 )
357                 {
358                     msg_Dbg( p_dec, "emulated startcode on next frame" );
359                     block_SkipByte( &p_sys->bytestream );
360                     p_sys->i_state = STATE_NOSYNC;
361                     p_sys->b_discontinuity = true;
362                     break;
363                 }
364
365                 /* Check info is in sync with previous one */
366                 if( i_next_channels_conf != p_sys->i_channels_conf ||
367                     i_next_rate != p_sys->i_rate ||
368                     i_next_layer != p_sys->i_layer ||
369                     i_next_frame_length != p_sys->i_frame_length )
370                 {
371                     /* Free bitrate only */
372                     if( p_sys->i_bit_rate == 0 )
373                     {
374                         p_sys->i_frame_size++;
375                         break;
376                     }
377
378                     msg_Dbg( p_dec, "parameters changed unexpectedly "
379                              "(emulated startcode ?)" );
380                     block_SkipByte( &p_sys->bytestream );
381                     p_sys->i_state = STATE_NOSYNC;
382                     break;
383                 }
384
385                 /* Free bitrate only */
386                 if( p_sys->i_bit_rate == 0 )
387                 {
388                     if( i_next_bit_rate != 0 )
389                     {
390                         p_sys->i_frame_size++;
391                         break;
392                     }
393                 }
394
395             }
396             else
397             {
398                 /* Free bitrate only */
399                 if( p_sys->i_bit_rate == 0 )
400                 {
401                     if( (unsigned int)p_sys->i_frame_size >
402                         p_sys->i_max_frame_size )
403                     {
404                         msg_Dbg( p_dec, "frame too big %d > %d "
405                                  "(emulated startcode ?)", p_sys->i_frame_size,
406                                  p_sys->i_max_frame_size );
407                         block_SkipByte( &p_sys->bytestream );
408                         p_sys->i_state = STATE_NOSYNC;
409                         p_sys->i_free_frame_size = MPGA_HEADER_SIZE;
410                         break;
411                     }
412
413                     p_sys->i_frame_size++;
414                     break;
415                 }
416
417                 msg_Dbg( p_dec, "emulated startcode "
418                          "(no startcode on following frame)" );
419                 p_sys->i_state = STATE_NOSYNC;
420                 block_SkipByte( &p_sys->bytestream );
421                 break;
422             }
423
424             p_sys->i_state = STATE_SEND_DATA;
425             break;
426
427         case STATE_GET_DATA:
428             /* Make sure we have enough data.
429              * (Not useful if we went through NEXT_SYNC) */
430             if( block_WaitBytes( &p_sys->bytestream,
431                                  p_sys->i_frame_size ) != VLC_SUCCESS )
432             {
433                 /* Need more data */
434                 return NULL;
435             }
436             p_sys->i_state = STATE_SEND_DATA;
437
438         case STATE_SEND_DATA:
439             if( !(p_buf = GetOutBuffer( p_dec, &p_out_buffer )) )
440             {
441                 //p_dec->b_error = true;
442                 return NULL;
443             }
444
445             /* Free bitrate only */
446             if( p_sys->i_bit_rate == 0 )
447             {
448                 p_sys->i_free_frame_size = p_sys->i_frame_size;
449             }
450
451             /* Copy the whole frame into the buffer. */
452             if (block_GetBytes( &p_sys->bytestream,
453                             p_buf, __MIN( (unsigned)p_sys->i_frame_size, p_out_buffer->i_buffer ) )) {
454                 block_Release(p_out_buffer);
455                 return NULL;
456             }
457
458             /* Get beginning of next frame for libmad */
459             if( !p_sys->b_packetizer )
460             {
461                 assert( p_out_buffer->i_buffer >= (unsigned)p_sys->i_frame_size + MAD_BUFFER_GUARD );
462                 memcpy( p_buf + p_sys->i_frame_size,
463                         p_header, MAD_BUFFER_GUARD );
464             }
465
466             p_sys->i_state = STATE_NOSYNC;
467
468             /* Make sure we don't reuse the same pts twice */
469             if( p_sys->i_pts == p_sys->bytestream.p_block->i_pts )
470                 p_sys->i_pts = p_sys->bytestream.p_block->i_pts = VLC_TS_INVALID;
471
472             /* So p_block doesn't get re-added several times */
473             p_block = block_BytestreamPop( &p_sys->bytestream );
474             if (pp_block)
475                 *pp_block = p_block;
476             else if (p_block)
477                 block_Release(p_block);
478
479             return p_out_buffer;
480         }
481     }
482
483     return NULL;
484 }
485
486 /*****************************************************************************
487  * GetOutBuffer:
488  *****************************************************************************/
489 static uint8_t *GetOutBuffer( decoder_t *p_dec, block_t **pp_out_buffer )
490 {
491     decoder_sys_t *p_sys = p_dec->p_sys;
492     uint8_t *p_buf;
493
494     if( p_dec->fmt_out.audio.i_rate != p_sys->i_rate )
495     {
496         msg_Dbg( p_dec, "MPGA channels:%d samplerate:%d bitrate:%d",
497                   p_sys->i_channels, p_sys->i_rate, p_sys->i_bit_rate );
498
499         date_Init( &p_sys->end_date, p_sys->i_rate, 1 );
500         date_Set( &p_sys->end_date, p_sys->i_pts );
501     }
502
503     p_dec->fmt_out.audio.i_rate     = p_sys->i_rate;
504     p_dec->fmt_out.audio.i_channels = p_sys->i_channels;
505     p_dec->fmt_out.audio.i_frame_length = p_sys->i_frame_length;
506     p_dec->fmt_out.audio.i_bytes_per_frame =
507         p_sys->i_max_frame_size + MAD_BUFFER_GUARD;
508
509     p_dec->fmt_out.audio.i_original_channels = p_sys->i_channels_conf;
510     p_dec->fmt_out.audio.i_physical_channels =
511         p_sys->i_channels_conf & AOUT_CHAN_PHYSMASK;
512
513     p_dec->fmt_out.i_bitrate = p_sys->i_bit_rate * 1000;
514
515     if( p_sys->b_packetizer )
516     {
517         block_t *p_sout_buffer = GetSoutBuffer( p_dec );
518         p_buf = p_sout_buffer ? p_sout_buffer->p_buffer : NULL;
519         *pp_out_buffer = p_sout_buffer;
520     }
521     else
522     {
523         block_t *p_aout_buffer = GetAoutBuffer( p_dec );
524         p_buf = p_aout_buffer ? p_aout_buffer->p_buffer : NULL;
525         *pp_out_buffer = p_aout_buffer;
526     }
527
528     return p_buf;
529 }
530
531 /*****************************************************************************
532  * GetAoutBuffer:
533  *****************************************************************************/
534 static block_t *GetAoutBuffer( decoder_t *p_dec )
535 {
536     decoder_sys_t *p_sys = p_dec->p_sys;
537     block_t *p_buf;
538
539     p_buf = decoder_NewAudioBuffer( p_dec, p_sys->i_frame_length );
540     if( p_buf == NULL ) return NULL;
541
542     p_buf->i_pts = date_Get( &p_sys->end_date );
543     p_buf->i_length = date_Increment( &p_sys->end_date, p_sys->i_frame_length )
544                       - p_buf->i_pts;
545     if( p_sys->b_discontinuity )
546         p_buf->i_flags |= BLOCK_FLAG_DISCONTINUITY;
547     p_sys->b_discontinuity = false;
548
549     /* Hack for libmad filter */
550     p_buf = block_Realloc( p_buf, 0, p_sys->i_frame_size + MAD_BUFFER_GUARD );
551
552     return p_buf;
553 }
554
555 /*****************************************************************************
556  * GetSoutBuffer:
557  *****************************************************************************/
558 static block_t *GetSoutBuffer( decoder_t *p_dec )
559 {
560     decoder_sys_t *p_sys = p_dec->p_sys;
561     block_t *p_block;
562
563     p_block = block_Alloc( p_sys->i_frame_size );
564     if( p_block == NULL ) return NULL;
565
566     p_block->i_pts = p_block->i_dts = date_Get( &p_sys->end_date );
567
568     p_block->i_length =
569         date_Increment( &p_sys->end_date, p_sys->i_frame_length ) - p_block->i_pts;
570
571     return p_block;
572 }
573
574 /*****************************************************************************
575  * CloseDecoder: clean up the decoder
576  *****************************************************************************/
577 static void CloseDecoder( vlc_object_t *p_this )
578 {
579     decoder_t *p_dec = (decoder_t *)p_this;
580     decoder_sys_t *p_sys = p_dec->p_sys;
581
582     block_BytestreamRelease( &p_sys->bytestream );
583
584     free( p_sys );
585 }
586
587 /*****************************************************************************
588  * SyncInfo: parse MPEG audio sync info
589  *****************************************************************************/
590 static int SyncInfo( uint32_t i_header, unsigned int * pi_channels,
591                      unsigned int * pi_channels_conf,
592                      unsigned int * pi_sample_rate, unsigned int * pi_bit_rate,
593                      unsigned int * pi_frame_length,
594                      unsigned int * pi_max_frame_size, unsigned int * pi_layer)
595 {
596     static const int ppi_bitrate[2][3][16] =
597     {
598         {
599             /* v1 l1 */
600             { 0, 32, 64, 96, 128, 160, 192, 224, 256, 288, 320, 352, 384,
601               416, 448, 0},
602             /* v1 l2 */
603             { 0, 32, 48, 56,  64,  80,  96, 112, 128, 160, 192, 224, 256,
604               320, 384, 0},
605             /* v1 l3 */
606             { 0, 32, 40, 48,  56,  64,  80,  96, 112, 128, 160, 192, 224,
607               256, 320, 0}
608         },
609
610         {
611             /* v2 l1 */
612             { 0, 32, 48, 56,  64,  80,  96, 112, 128, 144, 160, 176, 192,
613               224, 256, 0},
614             /* v2 l2 */
615             { 0,  8, 16, 24,  32,  40,  48,  56,  64,  80,  96, 112, 128,
616               144, 160, 0},
617             /* v2 l3 */
618             { 0,  8, 16, 24,  32,  40,  48,  56,  64,  80,  96, 112, 128,
619               144, 160, 0}
620         }
621     };
622
623     static const int ppi_samplerate[2][4] = /* version 1 then 2 */
624     {
625         { 44100, 48000, 32000, 0 },
626         { 22050, 24000, 16000, 0 }
627     };
628
629     int i_version, i_mode, i_emphasis;
630     bool b_padding, b_mpeg_2_5;
631     int i_frame_size = 0;
632     int i_bitrate_index, i_samplerate_index;
633     int i_max_bit_rate;
634
635     b_mpeg_2_5  = 1 - ((i_header & 0x100000) >> 20);
636     i_version   = 1 - ((i_header & 0x80000) >> 19);
637     *pi_layer   = 4 - ((i_header & 0x60000) >> 17);
638     //bool b_crc = !((i_header >> 16) & 0x01);
639     i_bitrate_index = (i_header & 0xf000) >> 12;
640     i_samplerate_index = (i_header & 0xc00) >> 10;
641     b_padding   = (i_header & 0x200) >> 9;
642     /* Extension */
643     i_mode      = (i_header & 0xc0) >> 6;
644     /* Modeext, copyright & original */
645     i_emphasis  = i_header & 0x3;
646
647     if( *pi_layer != 4 &&
648         i_bitrate_index < 0x0f &&
649         i_samplerate_index != 0x03 &&
650         i_emphasis != 0x02 )
651     {
652         switch ( i_mode )
653         {
654         case 0: /* stereo */
655         case 1: /* joint stereo */
656             *pi_channels = 2;
657             *pi_channels_conf = AOUT_CHAN_LEFT | AOUT_CHAN_RIGHT;
658             break;
659         case 2: /* dual-mono */
660             *pi_channels = 2;
661             *pi_channels_conf = AOUT_CHAN_LEFT | AOUT_CHAN_RIGHT
662                                 | AOUT_CHAN_DUALMONO;
663             break;
664         case 3: /* mono */
665             *pi_channels = 1;
666             *pi_channels_conf = AOUT_CHAN_CENTER;
667             break;
668         }
669         *pi_bit_rate = ppi_bitrate[i_version][*pi_layer-1][i_bitrate_index];
670         i_max_bit_rate = ppi_bitrate[i_version][*pi_layer-1][14];
671         *pi_sample_rate = ppi_samplerate[i_version][i_samplerate_index];
672
673         if ( b_mpeg_2_5 )
674         {
675             *pi_sample_rate >>= 1;
676         }
677
678         switch( *pi_layer )
679         {
680         case 1:
681             i_frame_size = ( 12000 * *pi_bit_rate / *pi_sample_rate +
682                            b_padding ) * 4;
683             *pi_max_frame_size = ( 12000 * i_max_bit_rate /
684                                  *pi_sample_rate + 1 ) * 4;
685             *pi_frame_length = 384;
686             break;
687
688         case 2:
689             i_frame_size = 144000 * *pi_bit_rate / *pi_sample_rate + b_padding;
690             *pi_max_frame_size = 144000 * i_max_bit_rate / *pi_sample_rate + 1;
691             *pi_frame_length = 1152;
692             break;
693
694         case 3:
695             i_frame_size = ( i_version ? 72000 : 144000 ) *
696                            *pi_bit_rate / *pi_sample_rate + b_padding;
697             *pi_max_frame_size = ( i_version ? 72000 : 144000 ) *
698                                  i_max_bit_rate / *pi_sample_rate + 1;
699             *pi_frame_length = i_version ? 576 : 1152;
700             break;
701
702         default:
703             break;
704         }
705
706         /* Free bitrate mode can support higher bitrates */
707         if( !*pi_bit_rate ) *pi_max_frame_size *= 2;
708     }
709     else
710     {
711         return -1;
712     }
713
714     return i_frame_size;
715 }