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