libs/mpega/stream.c

   1 /*
   2  * libmad - MPEG audio decoder library
   3  * Copyright (C) 2000-2004 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  * $Id$
  20  */
  21
  22 # ifdef HAVE_CONFIG_H
  23 #  include "config.h"
  24 # endif
  25
  26 # include "global.h"
  27
  28 # include <stdlib.h>
  29
  30 # include "bit.h"
  31 # include "stream.h"
  32
  33 /*
  34  * NAME:        stream->init()
  35  * DESCRIPTION: initialize stream struct
  36  */
  37 void mad_stream_init(struct mad_stream *stream)
  38 {
  39   stream->buffer     = 0;
  40   stream->bufend     = 0;
  41   stream->skiplen    = 0;
  42
  43   stream->sync       = 0;
  44   stream->freerate   = 0;
  45
  46   stream->this_frame = 0;
  47   stream->next_frame = 0;
  48   mad_bit_init(&stream->ptr, 0);
  49
  50   mad_bit_init(&stream->anc_ptr, 0);
  51   stream->anc_bitlen = 0;
  52
  53   stream->main_data  = 0;
  54   stream->md_len     = 0;
  55
  56   stream->options    = 0;
  57   stream->error      = MAD_ERROR_NONE;
  58 }
  59
  60 /*
  61  * NAME:        stream->finish()
  62  * DESCRIPTION: deallocate any dynamic memory associated with stream
  63  */
  64 void mad_stream_finish(struct mad_stream *stream)
  65 {
  66   if (stream->main_data) {
  67     free(stream->main_data);
  68     stream->main_data = 0;
  69   }
  70
  71   mad_bit_finish(&stream->anc_ptr);
  72   mad_bit_finish(&stream->ptr);
  73 }
  74
  75 /*
  76  * NAME:        stream->buffer()
  77  * DESCRIPTION: set stream buffer pointers
  78  */
  79 void mad_stream_buffer(struct mad_stream *stream,
  80                        unsigned char const *buffer, unsigned long length)
  81 {
  82   stream->buffer = buffer;
  83   stream->bufend = buffer + length;
  84
  85   stream->this_frame = buffer;
  86   stream->next_frame = buffer;
  87
  88   stream->sync = 1;
  89
  90   mad_bit_init(&stream->ptr, buffer);
  91 }
  92
  93 /*
  94  * NAME:        stream->skip()
  95  * DESCRIPTION: arrange to skip bytes before the next frame
  96  */
  97 void mad_stream_skip(struct mad_stream *stream, unsigned long length)
  98 {
  99   stream->skiplen += length;
 100 }
 101
 102 /*
 103  * NAME:        stream->sync()
 104  * DESCRIPTION: locate the next stream sync word
 105  */
 106 int mad_stream_sync(struct mad_stream *stream)
 107 {
 108   register unsigned char const *ptr, *end;
 109
 110   ptr = mad_bit_nextbyte(&stream->ptr);
 111   end = stream->bufend;
 112
 113   while (ptr < end - 1 &&
 114          !(ptr[0] == 0xff && (ptr[1] & 0xe0) == 0xe0))
 115     ++ptr;
 116
 117   if (end - ptr < MAD_BUFFER_GUARD)
 118     return -1;
 119
 120   mad_bit_init(&stream->ptr, ptr);
 121
 122   return 0;
 123 }
 124
 125 /*
 126  * NAME:        stream->errorstr()
 127  * DESCRIPTION: return a string description of the current error condition
 128  */
 129 char const *mad_stream_errorstr(struct mad_stream const *stream)
 130 {
 131   switch (stream->error) {
 132   case MAD_ERROR_NONE:           return "no error";
 133
 134   case MAD_ERROR_BUFLEN:         return "input buffer too small (or EOF)";
 135   case MAD_ERROR_BUFPTR:         return "invalid (null) buffer pointer";
 136
 137   case MAD_ERROR_NOMEM:          return "not enough memory";
 138
 139   case MAD_ERROR_LOSTSYNC:       return "lost synchronization";
 140   case MAD_ERROR_BADLAYER:       return "reserved header layer value";
 141   case MAD_ERROR_BADBITRATE:     return "forbidden bitrate value";
 142   case MAD_ERROR_BADSAMPLERATE:  return "reserved sample frequency value";
 143   case MAD_ERROR_BADEMPHASIS:    return "reserved emphasis value";
 144
 145   case MAD_ERROR_BADCRC:         return "CRC check failed";
 146   case MAD_ERROR_BADBITALLOC:    return "forbidden bit allocation value";
 147   case MAD_ERROR_BADSCALEFACTOR: return "bad scalefactor index";
 148   case MAD_ERROR_BADMODE:        return "bad bitrate/mode combination";
 149   case MAD_ERROR_BADFRAMELEN:    return "bad frame length";
 150   case MAD_ERROR_BADBIGVALUES:   return "bad big_values count";
 151   case MAD_ERROR_BADBLOCKTYPE:   return "reserved block_type";
 152   case MAD_ERROR_BADSCFSI:       return "bad scalefactor selection info";
 153   case MAD_ERROR_BADDATAPTR:     return "bad main_data_begin pointer";
 154   case MAD_ERROR_BADPART3LEN:    return "bad audio data length";
 155   case MAD_ERROR_BADHUFFTABLE:   return "bad Huffman table select";
 156   case MAD_ERROR_BADHUFFDATA:    return "Huffman data overrun";
 157   case MAD_ERROR_BADSTEREO:      return "incompatible block_type for JS";
 158   }
 159
 160   return 0;
 161 }