libmad/stream.c

   1 /*
   2  * libmad - MPEG audio decoder library
   3  * Copyright (C) 2000-2003 Underbit Technologies, Inc.
   4  *
   5  * This program is free software; you can redistribute it and/or modify
   6  * it under the terms of the GNU General Public License as published by
   7  * the Free Software Foundation; either version 2 of the License, or
   8  * (at your option) any later version.
   9  *
  10  * This program is distributed in the hope that it will be useful,
  11  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13  * GNU General Public License for more details.
  14  *
  15  * You should have received a copy of the GNU General Public License
  16  * along with this program; if not, write to the Free Software
  17  * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
  18  *
  19  */
  20
  21 # ifdef HAVE_CONFIG_H
  22 #  include "config.h"
  23 # endif
  24
  25 # include "global.h"
  26
  27 # include <stdlib.h>
  28
  29 # include "bit.h"
  30 # include "stream.h"
  31
  32 /*
  33  * NAME:        stream->init()
  34  * DESCRIPTION: initialize stream struct
  35  */
  36 void mad_stream_init(struct mad_stream *stream)
  37 {
  38   stream->buffer     = 0;
  39   stream->bufend     = 0;
  40   stream->skiplen    = 0;
  41
  42   stream->sync       = 0;
  43   stream->freerate   = 0;
  44
  45   stream->this_frame = 0;
  46   stream->next_frame = 0;
  47   mad_bit_init(&stream->ptr, 0);
  48
  49   mad_bit_init(&stream->anc_ptr, 0);
  50   stream->anc_bitlen = 0;
  51
  52   stream->main_data  = 0;
  53   stream->md_len     = 0;
  54
  55   stream->options    = 0;
  56   stream->error      = MAD_ERROR_NONE;
  57 }
  58
  59 /*
  60  * NAME:        stream->finish()
  61  * DESCRIPTION: deallocate any dynamic memory associated with stream
  62  */
  63 void mad_stream_finish(struct mad_stream *stream)
  64 {
  65   if (stream->main_data) {
  66     free(stream->main_data);
  67     stream->main_data = 0;
  68   }
  69
  70   mad_bit_finish(&stream->anc_ptr);
  71   mad_bit_finish(&stream->ptr);
  72 }
  73
  74 /*
  75  * NAME:        stream->buffer()
  76  * DESCRIPTION: set stream buffer pointers
  77  */
  78 void mad_stream_buffer(struct mad_stream *stream,
  79                        u8 const *buffer, u32 length)
  80 {
  81   stream->buffer = buffer;
  82   stream->bufend = buffer + length;
  83
  84   stream->this_frame = buffer;
  85   stream->next_frame = buffer;
  86
  87   stream->sync = 1;
  88
  89   mad_bit_init(&stream->ptr, buffer);
  90 }
  91
  92 /*
  93  * NAME:        stream->skip()
  94  * DESCRIPTION: arrange to skip bytes before the next frame
  95  */
  96 void mad_stream_skip(struct mad_stream *stream, u32 length)
  97 {
  98   stream->skiplen += length;
  99 }
 100
 101 /*
 102  * NAME:        stream->sync()
 103  * DESCRIPTION: locate the next stream sync word
 104  */
 105 s32 mad_stream_sync(struct mad_stream *stream)
 106 {
 107   register u8 const *ptr, *end;
 108
 109   ptr = mad_bit_nextbyte(&stream->ptr);
 110   end = stream->bufend;
 111
 112   while (ptr < end - 1 &&
 113          !(ptr[0] == 0xff && (ptr[1] & 0xe0) == 0xe0))
 114     ++ptr;
 115
 116   if (end - ptr < MAD_BUFFER_GUARD)
 117     return -1;
 118
 119   mad_bit_init(&stream->ptr, ptr);
 120
 121   return 0;
 122 }
 123
 124 /*
 125  * NAME:        stream->errorstr()
 126  * DESCRIPTION: return a string description of the current error condition
 127  */
 128 char const *mad_stream_errorstr(struct mad_stream const *stream)
 129 {
 130   switch (stream->error) {
 131   case MAD_ERROR_NONE:           return "no error";
 132
 133   case MAD_ERROR_BUFLEN:         return "input buffer too small (or EOF)";
 134   case MAD_ERROR_BUFPTR:         return "invalid (null) buffer pointer";
 135
 136   case MAD_ERROR_NOMEM:          return "not enough memory";
 137
 138   case MAD_ERROR_LOSTSYNC:       return "lost synchronization";
 139   case MAD_ERROR_BADLAYER:       return "reserved header layer value";
 140   case MAD_ERROR_BADBITRATE:     return "forbidden bitrate value";
 141   case MAD_ERROR_BADSAMPLERATE:  return "reserved sample frequency value";
 142   case MAD_ERROR_BADEMPHASIS:    return "reserved emphasis value";
 143
 144   case MAD_ERROR_BADCRC:         return "CRC check failed";
 145   case MAD_ERROR_BADBITALLOC:    return "forbidden bit allocation value";
 146   case MAD_ERROR_BADSCALEFACTOR: return "bad scalefactor index";
 147   case MAD_ERROR_BADFRAMELEN:    return "bad frame length";
 148   case MAD_ERROR_BADBIGVALUES:   return "bad big_values count";
 149   case MAD_ERROR_BADBLOCKTYPE:   return "reserved block_type";
 150   case MAD_ERROR_BADSCFSI:       return "bad scalefactor selection info";
 151   case MAD_ERROR_BADDATAPTR:     return "bad main_data_begin pointer";
 152   case MAD_ERROR_BADPART3LEN:    return "bad audio data length";
 153   case MAD_ERROR_BADHUFFTABLE:   return "bad Huffman table select";
 154   case MAD_ERROR_BADHUFFDATA:    return "Huffman data overrun";
 155   case MAD_ERROR_BADSTEREO:      return "incompatible block_type for JS";
 156   }
 157
 158   return 0;
 159 }