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
  37 #include "log.h"
  38 #include "syscalls.h"
  39 #include "defs.h"
  40 #include "speaker-protocol.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                           int nbytes) {
  94   struct stream_header header;
  95
  96   header.rate = rate;
  97   header.bits = bits;
  98   header.channels = channels;
  99   header.endian = ENDIAN_BIG;
 100   header.nbytes = nbytes;
 101   if(fwrite(&header, sizeof header, 1, outputfp) < 1)
 102     fatal(errno, "decoding %s: writing format header", path);
 103 }
 104
 105 /** @brief Dithering state
 106  * Filched from mpg321, which credits it to Robert Leslie */
 107 struct audio_dither {
 108   mad_fixed_t error[3];
 109   mad_fixed_t random;
 110 };
 111
 112 /** @brief 32-bit PRNG
 113  * Filched from mpg321, which credits it to Robert Leslie */
 114 static inline unsigned long prng(unsigned long state)
 115 {
 116   return (state * 0x0019660dL + 0x3c6ef35fL) & 0xffffffffL;
 117 }
 118
 119 /** @brief Generic linear sample quantize and dither routine
 120  * Filched from mpg321, which credits it to Robert Leslie */
 121 #define bits 16
 122 static long audio_linear_dither(mad_fixed_t sample,
 123                                 struct audio_dither *dither) {
 124   unsigned int scalebits;
 125   mad_fixed_t output, mask, rnd;
 126
 127   enum {
 128     MIN = -MAD_F_ONE,
 129     MAX =  MAD_F_ONE - 1
 130   };
 131
 132   /* noise shape */
 133   sample += dither->error[0] - dither->error[1] + dither->error[2];
 134
 135   dither->error[2] = dither->error[1];
 136   dither->error[1] = dither->error[0] / 2;
 137
 138   /* bias */
 139   output = sample + (1L << (MAD_F_FRACBITS + 1 - bits - 1));
 140
 141   scalebits = MAD_F_FRACBITS + 1 - bits;
 142   mask = (1L << scalebits) - 1;
 143
 144   /* dither */
 145   rnd  = prng(dither->random);
 146   output += (rnd & mask) - (dither->random & mask);
 147
 148   dither->random = rnd;
 149
 150   /* clip */
 151   if (output > MAX) {
 152     output = MAX;
 153
 154     if (sample > MAX)
 155       sample = MAX;
 156   }
 157   else if (output < MIN) {
 158     output = MIN;
 159
 160     if (sample < MIN)
 161       sample = MIN;
 162   }
 163
 164   /* quantize */
 165   output &= ~mask;
 166
 167   /* error feedback */
 168   dither->error[0] = sample - output;
 169
 170   /* scale */
 171   return output >> scalebits;
 172 }
 173 #undef bits
 174
 175 /** @brief MP3 output callback */
 176 static enum mad_flow mp3_output(void attribute((unused)) *data,
 177                                 struct mad_header const *header,
 178                                 struct mad_pcm *pcm) {
 179   size_t n = pcm->length;
 180   const mad_fixed_t *l = pcm->samples[0], *r = pcm->samples[1];
 181   static struct audio_dither ld[1], rd[1];
 182
 183   output_header(header->samplerate,
 184                 pcm->channels,
 185                 16,
 186                 2 * pcm->channels * pcm->length);
 187   switch(pcm->channels) {
 188   case 1:
 189     while(n--)
 190       output_16(audio_linear_dither(*l++, ld));
 191     break;
 192   case 2:
 193     while(n--) {
 194       output_16(audio_linear_dither(*l++, ld));
 195       output_16(audio_linear_dither(*r++, rd));
 196     }
 197     break;
 198   default:
 199     fatal(0, "decoding %s: unsupported channel count %d", path, pcm->channels);
 200   }
 201   return MAD_FLOW_CONTINUE;
 202 }
 203
 204 /** @brief MP3 input callback */
 205 static enum mad_flow mp3_input(void attribute((unused)) *data,
 206                                struct mad_stream *stream) {
 207   const size_t n = fill();
 208   fprintf(stderr, "n=%zu\n", n);
 209   if(!n)
 210     return MAD_FLOW_STOP;
 211   mad_stream_buffer(stream, buffer, n);
 212   return MAD_FLOW_CONTINUE;
 213 }
 214
 215
 216 /** @brief MP3 error callback */
 217 static enum mad_flow mp3_error(void attribute((unused)) *data,
 218                                struct mad_stream *stream,
 219                                struct mad_frame attribute((unused)) *frame) {
 220   if(0)
 221     /* Just generates pointless verbosity l-( */
 222     error(0, "decoding %s: %s (%#04x)",
 223           path, mad_stream_errorstr(stream), stream->error);
 224   return MAD_FLOW_CONTINUE;
 225 }
 226
 227 /** @brief MP3 decoder */
 228 static void decode_mp3(void) {
 229   struct mad_decoder mad[1];
 230
 231   open_input();
 232   mad_decoder_init(mad, 0/*data*/, mp3_input, 0/*header*/, 0/*filter*/,
 233                    mp3_output, mp3_error, 0/*message*/);
 234   if(mad_decoder_run(mad, MAD_DECODER_MODE_SYNC))
 235     exit(1);
 236   mad_decoder_finish(mad);
 237 }
 238
 239 /** @brief Lookup table of decoders */
 240 static const struct decoder decoders[] = {
 241   { "*.mp3", decode_mp3 },
 242   { "*.MP3", decode_mp3 },
 243   { 0, 0 }
 244 };
 245
 246 static const struct option options[] = {
 247   { "help", no_argument, 0, 'h' },
 248   { "version", no_argument, 0, 'V' },
 249   { 0, 0, 0, 0 }
 250 };
 251
 252 /* Display usage message and terminate. */
 253 static void help(void) {
 254   xprintf("Usage:\n"
 255           "  disorder-decode [OPTIONS] PATH\n"
 256           "Options:\n"
 257           "  --help, -h              Display usage message\n"
 258           "  --version, -V           Display version number\n"
 259           "\n"
 260           "Audio decoder for DisOrder.  Only intended to be used by speaker\n"
 261           "process, not for normal users.\n");
 262   xfclose(stdout);
 263   exit(0);
 264 }
 265
 266 /* Display version number and terminate. */
 267 static void version(void) {
 268   xprintf("disorder-decode version %s\n", disorder_version_string);
 269   xfclose(stdout);
 270   exit(0);
 271 }
 272
 273 int main(int argc, char **argv) {
 274   int n;
 275   const char *e;
 276
 277   set_progname(argv);
 278   if(!setlocale(LC_CTYPE, "")) fatal(errno, "calling setlocale");
 279   while((n = getopt_long(argc, argv, "hV", options, 0)) >= 0) {
 280     switch(n) {
 281     case 'h': help();
 282     case 'V': version();
 283     default: fatal(0, "invalid option");
 284     }
 285   }
 286   if(optind >= argc)
 287     fatal(0, "missing filename");
 288   if(optind + 1 < argc)
 289     fatal(0, "excess arguments");
 290   if((e = getenv("DISORDER_RAW_FD"))) {
 291     if(!(outputfp = fdopen(atoi(e), "wb")))
 292       fatal(errno, "fdopen");
 293   } else
 294     outputfp = stdout;
 295   path = argv[optind];
 296   for(n = 0;
 297       decoders[n].pattern
 298         && fnmatch(decoders[n].pattern, path, 0) != 0;
 299       ++n)
 300     ;
 301   if(!decoders[n].pattern)
 302     fatal(0, "cannot determine file type for %s", path);
 303   decoders[n].decode();
 304   xfclose(outputfp);
 305   return 0;
 306 }
 307
 308 /*
 309 Local Variables:
 310 c-basic-offset:2
 311 comment-column:40
 312 fill-column:79
 313 indent-tabs-mode:nil
 314 End:
 315 */