src/lpc10.c

   1 /* libSoX lpc-10 format.
   2  *
   3  * Copyright 2007 Reuben Thomas <rrt@sc3d.org>
   4  *
   5  * This library is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU Lesser General Public License as published by
   7  * the Free Software Foundation; either version 2.1 of the License, or (at
   8  * your option) any later version.
   9  *
  10  * This library 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 Lesser
  13  * General Public License for more details.
  14  *
  15  * You should have received a copy of the GNU Lesser General Public License
  16  * along with this library; if not, write to the Free Software Foundation,
  17  * Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
  18  */
  19
  20 #include "sox_i.h"
  21
  22 #ifdef EXTERNAL_LPC10
  23 #include <lpc10.h>
  24 #else
  25 #include "../lpc10/lpc10.h"
  26 #endif
  27
  28 /* Private data */
  29 typedef struct {
  30   struct lpc10_encoder_state *encst;
  31   float speech[LPC10_SAMPLES_PER_FRAME];
  32   unsigned samples;
  33   struct lpc10_decoder_state *decst;
  34 } priv_t;
  35
  36 /*
  37   Write the bits in bits[0] through bits[len-1] to file f, in "packed"
  38   format.
  39
  40   bits is expected to be an array of len integer values, where each
  41   integer is 0 to represent a 0 bit, and any other value represents a
  42   1 bit. This bit string is written to the file f in the form of
  43   several 8 bit characters. If len is not a multiple of 8, then the
  44   last character is padded with 0 bits -- the padding is in the least
  45   significant bits of the last byte. The 8 bit characters are "filled"
  46   in order from most significant bit to least significant.
  47 */
  48 static void write_bits(sox_format_t * ft, INT32 *bits, int len)
  49 {
  50   int i;
  51   uint8_t mask; /* The next bit position within the variable "data" to
  52                    place the next bit. */
  53   uint8_t data; /* The contents of the next byte to place in the
  54                    output. */
  55
  56   /* Fill in the array bits.
  57    * The first compressed output bit will be the most significant
  58    * bit of the byte, so initialize mask to 0x80.  The next byte of
  59    * compressed data is initially 0, and the desired bits will be
  60    * turned on below.
  61    */
  62   mask = 0x80;
  63   data = 0;
  64
  65   for (i = 0; i < len; i++) {
  66     /* Turn on the next bit of output data, if necessary. */
  67     if (bits[i]) {
  68       data |= mask;
  69     }
  70     /*
  71      * If the byte data is full, determined by mask becoming 0,
  72      * then write the byte to the output file, and reinitialize
  73      * data and mask for the next output byte.  Also add the byte
  74      * if (i == len-1), because if len is not a multiple of 8,
  75      * then mask won't yet be 0.  */
  76     mask >>= 1;
  77     if ((mask == 0) || (i == len-1)) {
  78       lsx_writeb(ft, data);
  79       data = 0;
  80       mask = 0x80;
  81     }
  82   }
  83 }
  84
  85 /*
  86   Read bits from file f into bits[0] through bits[len-1], in "packed"
  87   format.
  88
  89   Read ceiling(len/8) characters from file f, if that many are
  90   available to read, otherwise read to the end of the file. The first
  91   character's 8 bits, in order from MSB to LSB, are used to fill
  92   bits[0] through bits[7]. The second character's bits are used to
  93   fill bits[8] through bits[15], and so on. If ceiling(len/8)
  94   characters are available to read, and len is not a multiple of 8,
  95   then some of the least significant bits of the last character read
  96   are completely ignored. Every entry of bits[] that is modified is
  97   changed to either a 0 or a 1.
  98
  99   The number of bits successfully read is returned, and is always in
 100   the range 0 to len, inclusive. If it is less than len, it will
 101   always be a multiple of 8.
 102 */
 103 static int read_bits(sox_format_t * ft, INT32 *bits, int len)
 104 {
 105   int i;
 106   uint8_t c = 0;
 107
 108   /* Unpack the array bits into coded_frame. */
 109   for (i = 0; i < len; i++) {
 110     if (i % 8 == 0) {
 111       lsx_read_b_buf(ft, &c, (size_t) 1);
 112       if (lsx_eof(ft)) {
 113         return (i);
 114       }
 115     }
 116     if (c & (0x80 >> (i & 7))) {
 117       bits[i] = 1;
 118     } else {
 119       bits[i] = 0;
 120     }
 121   }
 122   return (len);
 123 }
 124
 125 static int startread(sox_format_t * ft)
 126 {
 127   priv_t * lpc = (priv_t *)ft->priv;
 128
 129   if ((lpc->decst = create_lpc10_decoder_state()) == NULL) {
 130     fprintf(stderr, "lpc10 could not allocate decoder state");
 131     return SOX_EOF;
 132   }
 133   lpc->samples = LPC10_SAMPLES_PER_FRAME;
 134   return lsx_check_read_params(ft, 1, 8000., SOX_ENCODING_LPC10, 0, (uint64_t)0, sox_false);
 135 }
 136
 137 static int startwrite(sox_format_t * ft)
 138 {
 139   priv_t * lpc = (priv_t *)ft->priv;
 140
 141   if ((lpc->encst = create_lpc10_encoder_state()) == NULL) {
 142     fprintf(stderr, "lpc10 could not allocate encoder state");
 143     return SOX_EOF;
 144   }
 145   lpc->samples = 0;
 146
 147   return SOX_SUCCESS;
 148 }
 149
 150 static size_t read_samples(sox_format_t * ft, sox_sample_t *buf, size_t len)
 151 {
 152   priv_t * lpc = (priv_t *)ft->priv;
 153   size_t nread = 0;
 154
 155   while (nread < len) {
 156     SOX_SAMPLE_LOCALS;
 157     /* Read more data if buffer is empty */
 158     if (lpc->samples == LPC10_SAMPLES_PER_FRAME) {
 159       INT32 bits[LPC10_BITS_IN_COMPRESSED_FRAME];
 160
 161       if (read_bits(ft, bits, LPC10_BITS_IN_COMPRESSED_FRAME) !=
 162           LPC10_BITS_IN_COMPRESSED_FRAME)
 163         break;
 164       lpc10_decode(bits, lpc->speech, lpc->decst);
 165       lpc->samples = 0;
 166     }
 167
 168     while (nread < len && lpc->samples < LPC10_SAMPLES_PER_FRAME)
 169       buf[nread++] = SOX_FLOAT_32BIT_TO_SAMPLE(lpc->speech[lpc->samples++], ft->clips);
 170   }
 171
 172   return nread;
 173 }
 174
 175 static size_t write_samples(sox_format_t * ft, const sox_sample_t *buf, size_t len)
 176 {
 177   priv_t * lpc = (priv_t *)ft->priv;
 178   size_t nwritten = 0;
 179
 180   while (len > 0) {
 181     while (len > 0 && lpc->samples < LPC10_SAMPLES_PER_FRAME) {
 182       SOX_SAMPLE_LOCALS;
 183       lpc->speech[lpc->samples++] = SOX_SAMPLE_TO_FLOAT_32BIT(buf[nwritten++], ft->clips);
 184       len--;
 185     }
 186
 187     if (lpc->samples == LPC10_SAMPLES_PER_FRAME) {
 188       INT32 bits[LPC10_BITS_IN_COMPRESSED_FRAME];
 189
 190       lpc10_encode(lpc->speech, bits, lpc->encst);
 191       write_bits(ft, bits, LPC10_BITS_IN_COMPRESSED_FRAME);
 192       lpc->samples = 0;
 193     }
 194   }
 195
 196   return nwritten;
 197 }
 198
 199 static int stopread(sox_format_t * ft)
 200 {
 201   priv_t * lpc = (priv_t *)ft->priv;
 202
 203   free(lpc->decst);
 204
 205   return SOX_SUCCESS;
 206 }
 207
 208 static int stopwrite(sox_format_t * ft)
 209 {
 210   priv_t * lpc = (priv_t *)ft->priv;
 211
 212   free(lpc->encst);
 213
 214   return SOX_SUCCESS;
 215 }
 216
 217 LSX_FORMAT_HANDLER(lpc10)
 218 {
 219   static char const * const names[] = {"lpc10", "lpc", NULL};
 220   static sox_rate_t   const write_rates[] = {8000, 0};
 221   static unsigned     const write_encodings[] = {SOX_ENCODING_LPC10, 0, 0};
 222   static sox_format_handler_t handler = {SOX_LIB_VERSION_CODE,
 223     "Low bandwidth, robotic sounding speech compression", names, SOX_FILE_MONO,
 224     startread, read_samples, stopread,
 225     startwrite, write_samples, stopwrite,
 226     NULL, write_encodings, write_rates, sizeof(priv_t)
 227   };
 228   return &handler;
 229 }