mdw@git.distorted.org.uk Git - disorder/blob - server/decode.c

   1 /*
   2  * This file is part of DisOrder
   3  * Copyright (C) 2007 Richard Kettlewell
   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, but
  11  * WITHOUT ANY WARRANTY; without even the implied warranty of
  12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13  * 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
  18  * USA
  19  */
  20 /** @file server/decode.c
  21  * @brief General-purpose decoder for use by speaker process
  22  */
  23
  24 #include <config.h>
  25 #include "types.h"
  26
  27 #include <getopt.h>
  28 #include <unistd.h>
  29 #include <fcntl.h>
  30 #include <errno.h>
  31 #include <stdlib.h>
  32 #include <locale.h>
  33 #include <assert.h>
  34 #include <fnmatch.h>
  35 #include <mad.h>
  36 #include <ao/ao.h>
  37
  38 #include "log.h"
  39 #include "syscalls.h"
  40 #include "defs.h"
  41
  42 /** @brief Encoding lookup table type */
  43 struct decoder {
  44   /** @brief Glob pattern matching file */
  45   const char *pattern;
  46   /** @brief Decoder function */
  47   void (*decode)(void);
  48 };
  49
  50 /** @brief Input file */
  51 static int inputfd;
  52
  53 /** @brief Output file */
  54 static FILE *outputfp;
  55
  56 /** @brief Filename */
  57 static const char *path;
  58
  59 /** @brief Input buffer */
  60 static unsigned char buffer[1048576];
  61
  62 /** @brief Open the input file */
  63 static void open_input(void) {
  64   if((inputfd = open(path, O_RDONLY)) < 0)
  65     fatal(errno, "opening %s", path);
  66 }
  67
  68 /** @brief Fill the buffer
  69  * @return Number of bytes read
  70  */
  71 static size_t fill(void) {
  72   int n = read(inputfd, buffer, sizeof buffer);
  73
  74   if(n < 0)
  75     fatal(errno, "reading from %s", path);
  76   return n;
  77 }
  78
  79 /** @brief Write a 16-bit word in bigendian format */
  80 static inline void output_16(uint16_t n) {
  81   if(putc(n >> 8, outputfp) < 0
  82      || putc(n & 0xFF, outputfp) < 0)
  83     fatal(errno, "decoding %s: output error", path);
  84 }
  85
  86 /** @brief Write the header
  87  * If called more than once, either does nothing (if you kept the same
  88  * output encoding) or fails (if you changed it).
  89  */
  90 static void output_header(int rate,
  91                           int channels,
  92                           int bits) {
  93   static int already_written_header;
  94   struct ao_sample_format format;
  95
  96   if(!already_written_header) {
  97      format.rate = rate;
  98      format.bits = bits;
  99      format.channels = channels;
 100      format.byte_format = AO_FMT_BIG;
 101      if(fwrite(&format, sizeof format, 1, outputfp) < 1)
 102        fatal(errno, "decoding %s: writing format header", path);
 103      already_written_header = 1;
 104    }
 105 }
 106
 107 /** @brief Dithering state
 108  * Filched from mpg321, which credits it to Robert Leslie */
 109 struct audio_dither {
 110   mad_fixed_t error[3];
 111   mad_fixed_t random;
 112 };
 113
 114 /** @brief 32-bit PRNG
 115  * Filched from mpg321, which credits it to Robert Leslie */
 116 static inline unsigned long prng(unsigned long state)
 117 {
 118   return (state * 0x0019660dL + 0x3c6ef35fL) & 0xffffffffL;
 119 }
 120
 121 /** @brief Generic linear sample quantize and dither routine
 122  * Filched from mpg321, which credits it to Robert Leslie */
 123 #define bits 16
 124 static long audio_linear_dither(mad_fixed_t sample,
 125                                 struct audio_dither *dither) {
 126   unsigned int scalebits;
 127   mad_fixed_t output, mask, rnd;
 128
 129   enum {
 130     MIN = -MAD_F_ONE,
 131     MAX =  MAD_F_ONE - 1
 132   };
 133
 134   /* noise shape */
 135   sample += dither->error[0] - dither->error[1] + dither->error[2];
 136
 137   dither->error[2] = dither->error[1];
 138   dither->error[1] = dither->error[0] / 2;
 139
 140   /* bias */
 141   output = sample + (1L << (MAD_F_FRACBITS + 1 - bits - 1));
 142
 143   scalebits = MAD_F_FRACBITS + 1 - bits;
 144   mask = (1L << scalebits) - 1;
 145
 146   /* dither */
 147   rnd  = prng(dither->random);
 148   output += (rnd & mask) - (dither->random & mask);
 149
 150   dither->random = rnd;
 151
 152   /* clip */
 153   if (output > MAX) {
 154     output = MAX;
 155
 156     if (sample > MAX)
 157       sample = MAX;
 158   }
 159   else if (output < MIN) {
 160     output = MIN;
 161
 162     if (sample < MIN)
 163       sample = MIN;
 164   }
 165
 166   /* quantize */
 167   output &= ~mask;
 168
 169   /* error feedback */
 170   dither->error[0] = sample - output;
 171
 172   /* scale */
 173   return output >> scalebits;
 174 }
 175 #undef bits
 176
 177 /** @brief MP3 output callback */
 178 static enum mad_flow mp3_output(void attribute((unused)) *data,
 179                                 struct mad_header const *header,
 180                                 struct mad_pcm *pcm) {
 181   size_t n = pcm->length;
 182   const mad_fixed_t *l = pcm->samples[0], *r = pcm->samples[1];
 183   static struct audio_dither ld[1], rd[1];
 184
 185   output_header(header->samplerate,
 186                 pcm->channels,
 187                 16);
 188   switch(pcm->channels) {
 189   case 1:
 190     while(n--)
 191       output_16(audio_linear_dither(*l++, ld));
 192     break;
 193   case 2:
 194     while(n--) {
 195       output_16(audio_linear_dither(*l++, ld));
 196       output_16(audio_linear_dither(*r++, rd));
 197     }
 198     break;
 199   default:
 200     fatal(0, "decoding %s: unsupported channel count %d", path, pcm->channels);
 201   }
 202   return MAD_FLOW_CONTINUE;
 203 }
 204
 205 /** @brief MP3 input callback */
 206 static enum mad_flow mp3_input(void attribute((unused)) *data,
 207                                struct mad_stream *stream) {
 208   const size_t n = fill();
 209   fprintf(stderr, "n=%zu\n", n);
 210   if(!n)
 211     return MAD_FLOW_STOP;
 212   mad_stream_buffer(stream, buffer, n);
 213   return MAD_FLOW_CONTINUE;
 214 }
 215
 216
 217 /** @brief MP3 error callback */
 218 static enum mad_flow mp3_error(void attribute((unused)) *data,
 219                                struct mad_stream *stream,
 220                                struct mad_frame attribute((unused)) *frame) {
 221   error(0, "decoding %s: %s (%#04x)",
 222         path, mad_stream_errorstr(stream), stream->error);
 223   return MAD_FLOW_CONTINUE;
 224 }
 225
 226 /** @brief MP3 header callback */
 227 static enum mad_flow mp3_header(void attribute((unused)) *data,
 228                                 struct mad_header const *header) {
 229   output_header(header->samplerate,
 230                 MAD_NCHANNELS(header),
 231                 16);
 232   return MAD_FLOW_CONTINUE;
 233 }
 234
 235 /** @brief MP3 decoder */
 236 static void decode_mp3(void) {
 237   struct mad_decoder mad[1];
 238
 239   open_input();
 240   mad_decoder_init(mad, 0/*data*/, mp3_input, mp3_header, 0/*filter*/,
 241                    mp3_output, mp3_error, 0/*message*/);
 242   if(mad_decoder_run(mad, MAD_DECODER_MODE_SYNC))
 243     exit(1);
 244   mad_decoder_finish(mad);
 245 }
 246
 247 /** @brief Lookup table of decoders */
 248 static const struct decoder decoders[] = {
 249   { "*.mp3", decode_mp3 },
 250   { "*.MP3", decode_mp3 },
 251   { 0, 0 }
 252 };
 253
 254 static const struct option options[] = {
 255   { "help", no_argument, 0, 'h' },
 256   { "version", no_argument, 0, 'V' },
 257   { 0, 0, 0, 0 }
 258 };
 259
 260 /* Display usage message and terminate. */
 261 static void help(void) {
 262   xprintf("Usage:\n"
 263           "  disorder-decode [OPTIONS] PATH\n"
 264           "Options:\n"
 265           "  --help, -h              Display usage message\n"
 266           "  --version, -V           Display version number\n"
 267           "\n"
 268           "Audio decoder for DisOrder.  Only intended to be used by speaker\n"
 269           "process, not for normal users.\n");
 270   xfclose(stdout);
 271   exit(0);
 272 }
 273
 274 /* Display version number and terminate. */
 275 static void version(void) {
 276   xprintf("disorder-decode version %s\n", disorder_version_string);
 277   xfclose(stdout);
 278   exit(0);
 279 }
 280
 281 int main(int argc, char **argv) {
 282   int n;
 283   const char *e;
 284
 285   set_progname(argv);
 286   if(!setlocale(LC_CTYPE, "")) fatal(errno, "calling setlocale");
 287   while((n = getopt_long(argc, argv, "hV", options, 0)) >= 0) {
 288     switch(n) {
 289     case 'h': help();
 290     case 'V': version();
 291     default: fatal(0, "invalid option");
 292     }
 293   }
 294   if(optind >= argc)
 295     fatal(0, "missing filename");
 296   if(optind + 1 < argc)
 297     fatal(0, "excess arguments");
 298   if((e = getenv("DISORDER_RAW_FD"))) {
 299     if(!(outputfp = fdopen(atoi(e), "wb")))
 300       fatal(errno, "fdopen");
 301   } else
 302     outputfp = stdout;
 303   path = argv[optind];
 304   for(n = 0;
 305       decoders[n].pattern
 306         && fnmatch(decoders[n].pattern, path, 0) != 0;
 307       ++n)
 308     ;
 309   if(!decoders[n].pattern)
 310     fatal(0, "cannot determine file type for %s", path);
 311   decoders[n].decode();
 312   xfclose(outputfp);
 313   return 0;
 314 }
 315
 316 /*
 317 Local Variables:
 318 c-basic-offset:2
 319 comment-column:40
 320 fill-column:79
 321 indent-tabs-mode:nil
 322 End:
 323 */