apps/codecs/libmad/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 "bit.h"
  29 # include "stream.h"
  30
  31 /*
  32  * NAME:        stream->init()
  33  * DESCRIPTION: initialize stream struct
  34  */
  35 void mad_stream_init(struct mad_stream *stream)
  36 {
  37   stream->buffer     = 0;
  38   stream->bufend     = 0;
  39   stream->skiplen    = 0;
  40
  41   stream->sync       = 0;
  42   stream->freerate   = 0;
  43
  44   stream->this_frame = 0;
  45   stream->next_frame = 0;
  46   mad_bit_init(&stream->ptr, 0);
  47
  48   mad_bit_init(&stream->anc_ptr, 0);
  49   stream->anc_bitlen = 0;
  50
  51 /* rockbox: comment this to avoid allocation in following code. main_data is
  52  * linked to an array in rockbox' apps/codecs/mpa.c before calling this.
  53   stream->main_data  = 0;
  54 */
  55   stream->md_len     = 0;
  56
  57   stream->options    = 0;
  58   stream->error      = MAD_ERROR_NONE;
  59 }
  60
  61 /*
  62  * NAME:        stream->finish()
  63  * DESCRIPTION: deallocate any dynamic memory associated with stream
  64  */
  65 void mad_stream_finish(struct mad_stream *stream)
  66 {
  67   if (stream->main_data) {
  68     free(stream->main_data);
  69     stream->main_data = 0;
  70   }
  71
  72   mad_bit_finish(&stream->anc_ptr);
  73   mad_bit_finish(&stream->ptr);
  74 }
  75
  76 /*
  77  * NAME:        stream->buffer()
  78  * DESCRIPTION: set stream buffer pointers
  79  */
  80 void mad_stream_buffer(struct mad_stream *stream,
  81                        unsigned char const *buffer, unsigned long length)
  82 {
  83   stream->buffer = buffer;
  84   stream->bufend = buffer + length;
  85
  86   stream->this_frame = buffer;
  87   stream->next_frame = buffer;
  88
  89   stream->sync = 1;
  90
  91   mad_bit_init(&stream->ptr, buffer);
  92 }
  93
  94 /*
  95  * NAME:        stream->skip()
  96  * DESCRIPTION: arrange to skip bytes before the next frame
  97  */
  98 void mad_stream_skip(struct mad_stream *stream, unsigned long length)
  99 {
 100   stream->skiplen += length;
 101 }
 102
 103 /*
 104  * NAME:        stream->sync()
 105  * DESCRIPTION: locate the next stream sync word
 106  */
 107 int mad_stream_sync(struct mad_stream *stream)
 108 {
 109   register unsigned char const *ptr, *end;
 110
 111   ptr = mad_bit_nextbyte(&stream->ptr);
 112   end = stream->bufend;
 113
 114   while (ptr < end - 1 &&
 115          !(ptr[0] == 0xff && (ptr[1] & 0xe0) == 0xe0))
 116     ++ptr;
 117
 118   if (end - ptr < MAD_BUFFER_GUARD)
 119     return -1;
 120
 121   mad_bit_init(&stream->ptr, ptr);
 122
 123   return 0;
 124 }
 125
 126 /*
 127  * NAME:        stream->errorstr()
 128  * DESCRIPTION: return a string description of the current error condition
 129  */
 130 char const *mad_stream_errorstr(struct mad_stream const *stream)
 131 {
 132   switch (stream->error) {
 133   case MAD_ERROR_NONE:           return "no error";
 134
 135   case MAD_ERROR_BUFLEN:         return "input buffer too small (or EOF)";
 136   case MAD_ERROR_BUFPTR:         return "invalid (null) buffer pointer";
 137
 138   case MAD_ERROR_NOMEM:          return "not enough memory";
 139
 140   case MAD_ERROR_LOSTSYNC:       return "lost synchronization";
 141   case MAD_ERROR_BADLAYER:       return "reserved header layer value";
 142   case MAD_ERROR_BADBITRATE:     return "forbidden bitrate value";
 143   case MAD_ERROR_BADSAMPLERATE:  return "reserved sample frequency value";
 144   case MAD_ERROR_BADEMPHASIS:    return "reserved emphasis value";
 145
 146   case MAD_ERROR_BADCRC:         return "CRC check failed";
 147   case MAD_ERROR_BADBITALLOC:    return "forbidden bit allocation value";
 148   case MAD_ERROR_BADSCALEFACTOR: return "bad scalefactor index";
 149   case MAD_ERROR_BADMODE:        return "bad bitrate/mode combination";
 150   case MAD_ERROR_BADFRAMELEN:    return "bad frame length";
 151   case MAD_ERROR_BADBIGVALUES:   return "bad big_values count";
 152   case MAD_ERROR_BADBLOCKTYPE:   return "reserved block_type";
 153   case MAD_ERROR_BADSCFSI:       return "bad scalefactor selection info";
 154   case MAD_ERROR_BADDATAPTR:     return "bad main_data_begin pointer";
 155   case MAD_ERROR_BADPART3LEN:    return "bad audio data length";
 156   case MAD_ERROR_BADHUFFTABLE:   return "bad Huffman table select";
 157   case MAD_ERROR_BADHUFFDATA:    return "Huffman data overrun";
 158   case MAD_ERROR_BADSTEREO:      return "incompatible block_type for JS";
 159   }
 160
 161   return 0;
 162 }