stream.cpp

00001 /*
00002  * libmad - MPEG audio decoder library
00003  * Copyright (C) 2000-2004 Underbit Technologies, Inc.
00004  *
00005  * This program is free software; you can redistribute it and/or modify
00006  * it under the terms of the GNU General Public License as published by
00007  * the Free Software Foundation; either version 2 of the License, or
00008  * (at your option) any later version.
00009  *
00010  * This program is distributed in the hope that it will be useful,
00011  * but WITHOUT ANY WARRANTY; without even the implied warranty of
00012  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
00013  * GNU General Public License for more details.
00014  *
00015  * You should have received a copy of the GNU General Public License
00016  * along with this program; if not, write to the Free Software
00017  * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
00018  *
00019  * $Id: stream.c,v 1.1 2010/11/23 20:12:57 andy Exp $
00020  */
00021 
00022 #  include "config.h"
00023 
00024 # include "global.h"
00025 
00026 # include <stdlib.h>
00027 
00028 # include "bit.h"
00029 # include "stream.h"
00030 
00031 /*
00032  * NAME:    stream->init()
00033  * DESCRIPTION: initialize stream struct
00034  */
00035 void mad_stream_init(struct mad_stream *stream)
00036 {
00037   stream->buffer     = 0;
00038   stream->bufend     = 0;
00039   stream->skiplen    = 0;
00040 
00041   stream->sync       = 0;
00042   stream->freerate   = 0;
00043 
00044   stream->this_frame = 0;
00045   stream->next_frame = 0;
00046   mad_bit_init(&stream->ptr, 0);
00047 
00048   mad_bit_init(&stream->anc_ptr, 0);
00049   stream->anc_bitlen = 0;
00050 
00051   stream->main_data  = 0;
00052   stream->md_len     = 0;
00053 
00054   stream->options    = 0;
00055   stream->error      = MAD_ERROR_NONE;
00056 }
00057 
00058 /*
00059  * NAME:    stream->finish()
00060  * DESCRIPTION: deallocate any dynamic memory associated with stream
00061  */
00062 void mad_stream_finish(struct mad_stream *stream)
00063 {
00064   if (stream->main_data) {
00065 #if !defined(TARGET_LPC1768)
00066     free(stream->main_data);
00067 #endif
00068     stream->main_data = 0;
00069   }
00070 
00071   mad_bit_finish(&stream->anc_ptr);
00072   mad_bit_finish(&stream->ptr);
00073 }
00074 
00075 /*
00076  * NAME:    stream->buffer()
00077  * DESCRIPTION: set stream buffer pointers
00078  */
00079 void mad_stream_buffer(struct mad_stream *stream,
00080                unsigned char const *buffer, unsigned long length)
00081 {
00082   stream->buffer = buffer;
00083   stream->bufend = buffer + length;
00084 
00085   stream->this_frame = buffer;
00086   stream->next_frame = buffer;
00087 
00088   stream->sync = 1;
00089 
00090   mad_bit_init(&stream->ptr, buffer);
00091 }
00092 
00093 /*
00094  * NAME:    stream->skip()
00095  * DESCRIPTION: arrange to skip bytes before the next frame
00096  */
00097 void mad_stream_skip(struct mad_stream *stream, unsigned long length)
00098 {
00099   stream->skiplen += length;
00100 }
00101 
00102 /*
00103  * NAME:    stream->sync()
00104  * DESCRIPTION: locate the next stream sync word
00105  */
00106 int mad_stream_sync(struct mad_stream *stream)
00107 {
00108   register unsigned char const *ptr, *end;
00109 
00110   ptr = mad_bit_nextbyte(&stream->ptr);
00111   end = stream->bufend;
00112 
00113   while (ptr < end - 1 &&
00114      !(ptr[0] == 0xff && (ptr[1] & 0xe0) == 0xe0))
00115     ++ptr;
00116 
00117   if (end - ptr < MAD_BUFFER_GUARD)
00118     return -1;
00119 
00120   mad_bit_init(&stream->ptr, ptr);
00121 
00122   return 0;
00123 }
00124 
00125 /*
00126  * NAME:    stream->errorstr()
00127  * DESCRIPTION: return a string description of the current error condition
00128  */
00129 char const *mad_stream_errorstr(struct mad_stream const *stream)
00130 {
00131   switch (stream->error) {
00132   case MAD_ERROR_NONE:       return "no error";
00133 
00134   case MAD_ERROR_BUFLEN:     return "input buffer too small (or EOF)";
00135   case MAD_ERROR_BUFPTR:     return "invalid (null) buffer pointer";
00136 
00137   case MAD_ERROR_NOMEM:      return "not enough memory";
00138 
00139   case MAD_ERROR_LOSTSYNC:   return "lost synchronization";
00140   case MAD_ERROR_BADLAYER:   return "reserved header layer value";
00141   case MAD_ERROR_BADBITRATE:     return "forbidden bitrate value";
00142   case MAD_ERROR_BADSAMPLERATE:  return "reserved sample frequency value";
00143   case MAD_ERROR_BADEMPHASIS:    return "reserved emphasis value";
00144 
00145   case MAD_ERROR_BADCRC:     return "CRC check failed";
00146   case MAD_ERROR_BADBITALLOC:    return "forbidden bit allocation value";
00147   case MAD_ERROR_BADSCALEFACTOR: return "bad scalefactor index";
00148   case MAD_ERROR_BADMODE:    return "bad bitrate/mode combination";
00149   case MAD_ERROR_BADFRAMELEN:    return "bad frame length";
00150   case MAD_ERROR_BADBIGVALUES:   return "bad big_values count";
00151   case MAD_ERROR_BADBLOCKTYPE:   return "reserved block_type";
00152   case MAD_ERROR_BADSCFSI:   return "bad scalefactor selection info";
00153   case MAD_ERROR_BADDATAPTR:     return "bad main_data_begin pointer";
00154   case MAD_ERROR_BADPART3LEN:    return "bad audio data length";
00155   case MAD_ERROR_BADHUFFTABLE:   return "bad Huffman table select";
00156   case MAD_ERROR_BADHUFFDATA:    return "Huffman data overrun";
00157   case MAD_ERROR_BADSTEREO:  return "incompatible block_type for JS";
00158   }
00159 
00160   return 0;
00161 }