swfdec/swfdec_audio_decoder_adpcm.c

   1 /* Swfdec
   2  * Copyright (C) 2006-2008 Benjamin Otte <otte@gnome.org>
   3  *
   4  * This library is free software; you can redistribute it and/or
   5  * modify it under the terms of the GNU Lesser General Public
   6  * License as published by the Free Software Foundation; either
   7  * version 2.1 of the License, or (at your option) any later version.
   8  *
   9  * This library is distributed in the hope that it will be useful,
  10  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  12  * Lesser General Public License for more details.
  13  *
  14  * You should have received a copy of the GNU Lesser General Public
  15  * License along with this library; if not, write to the Free Software
  16  * Foundation, Inc., 51 Franklin Street, Fifth Floor,
  17  * Boston, MA  02110-1301  USA
  18  */
  19
  20 #ifdef HAVE_CONFIG_H
  21 #include "config.h"
  22 #endif
  23
  24 #include "swfdec_audio_decoder_adpcm.h"
  25 #include "swfdec_debug.h"
  26 #include "swfdec_internal.h"
  27
  28 G_DEFINE_TYPE (SwfdecAudioDecoderAdpcm, swfdec_audio_decoder_adpcm, SWFDEC_TYPE_AUDIO_DECODER)
  29
  30 static gboolean
  31 swfdec_audio_decoder_adpcm_prepare (guint codec, SwfdecAudioFormat format, char **missing)
  32 {
  33   return codec == SWFDEC_AUDIO_CODEC_ADPCM;
  34 }
  35
  36 static SwfdecAudioDecoder *
  37 swfdec_audio_decoder_adpcm_create (guint codec, SwfdecAudioFormat format, SwfdecBuffer *data)
  38 {
  39   if (codec != SWFDEC_AUDIO_CODEC_ADPCM)
  40     return NULL;
  41
  42   return g_object_new (SWFDEC_TYPE_AUDIO_DECODER_ADPCM, NULL);
  43 }
  44
  45 static const int indexTable[4][16] = {
  46   { -1, 2 },
  47   { -1, -1, 2, 4 },
  48   { -1, -1, -1, -1, 2, 4, 6, 8 },
  49   { -1, -1, -1, -1, -1, -1, -1, -1, 1, 2, 4, 6, 8, 10, 13, 16 }
  50 };
  51
  52 static const int stepSizeTable[89] = {
  53     7, 8, 9, 10, 11, 12, 13, 14, 16, 17,
  54     19, 21, 23, 25, 28, 31, 34, 37, 41, 45,
  55     50, 55, 60, 66, 73, 80, 88, 97, 107, 118,
  56     130, 143, 157, 173, 190, 209, 230, 253, 279, 307,
  57     337, 371, 408, 449, 494, 544, 598, 658, 724, 796,
  58     876, 963, 1060, 1166, 1282, 1411, 1552, 1707, 1878, 2066,
  59     2272, 2499, 2749, 3024, 3327, 3660, 4026, 4428, 4871, 5358,
  60     5894, 6484, 7132, 7845, 8630, 9493, 10442, 11487, 12635, 13899,
  61     15289, 16818, 18500, 20350, 22385, 24623, 27086, 29794, 32767
  62 };
  63
  64 static SwfdecBuffer *
  65 swfdec_audio_decoder_adpcm_decode_chunk (SwfdecBits *bits, guint n_bits,
  66     guint channels, guint granularity)
  67 {
  68   SwfdecBuffer *ret;
  69   guint len, repeat;
  70   guint i, j, ch;
  71   guint index[2];
  72   int pred[2];
  73   gint16 *out;
  74   guint delta, sign, sign_mask;
  75   int diff;
  76   const int *realIndexTable;
  77   guint step[2];
  78
  79   /* for scaling up the audio to 44100kHz */
  80   repeat = 2 * granularity - channels;
  81
  82   realIndexTable = indexTable[n_bits - 2];
  83   for (ch = 0; ch < channels; ch++) {
  84     /* can't use get_s16 here since that would be aligned */
  85     pred[ch] = swfdec_bits_getsbits (bits, 16);
  86     index[ch] = swfdec_bits_getbits (bits, 6);
  87     if (index[ch] >= G_N_ELEMENTS (stepSizeTable)) {
  88       SWFDEC_ERROR ("initial index too big: %u, max allowed is %td",
  89           index[ch], G_N_ELEMENTS (stepSizeTable) - 1);
  90       index[ch] = G_N_ELEMENTS (stepSizeTable) - 1;
  91     }
  92     step[ch] = stepSizeTable[index[ch]];
  93   }
  94   len = swfdec_bits_left (bits) / channels / n_bits;
  95   len = MIN (len, 4095);
  96   ret = swfdec_buffer_new ((len + 1) * sizeof (gint16) * granularity * 2);
  97   out = (gint16 *) (void *) ret->data;
  98   /* output initial value */
  99   SWFDEC_LOG ("decoding %u samples", len + 1);
 100   for (ch = 0; ch < channels; ch++)
 101     *out++ = pred[ch];
 102   /* upscale to 44.1kHz */
 103   for (ch = 0; ch < repeat; ch++) {
 104     *out = out[-(gssize) channels];
 105     out++;
 106   }
 107
 108   sign_mask = 1 << (n_bits - 1);
 109   for (i = 0; i < len; i++) {
 110     for (ch = 0; ch < channels; ch++) {
 111       /* Step 1 - get the delta value */
 112       delta = swfdec_bits_getbits (bits, n_bits);
 113
 114       /* Step 2 - Separate sign and magnitude */
 115       sign = delta & sign_mask;
 116       delta -= sign;
 117
 118       /* Step 3 - Find new index value (for later) */
 119       index[ch] += realIndexTable[delta];
 120       if ( index[ch] >= G_MAXINT ) index[ch] = 0; /* underflow */
 121       if ( index[ch] >= G_N_ELEMENTS (stepSizeTable) ) index[ch] = G_N_ELEMENTS (stepSizeTable) - 1;
 122
 123       /* Step 4 - Compute difference and new predicted value */
 124       j = n_bits - 1;
 125       diff = step[ch] >> j;
 126       do {
 127         j--;
 128         if (delta & 1)
 129           diff += step[ch] >> j;
 130         delta >>= 1;
 131       } while (j > 0 && delta);
 132
 133       if ( sign )
 134         pred[ch] -= diff;
 135       else
 136         pred[ch] += diff;
 137
 138       /* Step 5 - clamp output value */
 139       pred[ch] = CLAMP (pred[ch], -32768, 32767);
 140
 141       /* Step 6 - Update step value */
 142       step[ch] = stepSizeTable[index[ch]];
 143
 144       /* Step 7 - Output value */
 145       *out++ = pred[ch];
 146     }
 147
 148     /* upscale to 44.1kHz */
 149     for (ch = 0; ch < repeat; ch++) {
 150       *out = out[-(gssize) channels];
 151       out++;
 152     }
 153   }
 154   return ret;
 155 }
 156
 157 static void
 158 swfdec_audio_decoder_adpcm_push (SwfdecAudioDecoder *dec, SwfdecBuffer *buffer)
 159 {
 160   SwfdecAudioDecoderAdpcm *adpcm = (SwfdecAudioDecoderAdpcm *) dec;
 161   guint channels, n_bits, granularity;
 162   SwfdecBits bits;
 163
 164   if (buffer == NULL)
 165     return;
 166
 167   channels = swfdec_audio_format_get_channels (dec->format);
 168   granularity = swfdec_audio_format_get_granularity (dec->format);
 169   swfdec_bits_init (&bits, buffer);
 170   n_bits = swfdec_bits_getbits (&bits, 2) + 2;
 171   SWFDEC_DEBUG ("starting decoding: %u channels, %u bits", channels, n_bits);
 172   /* 22 is minimum required header size */
 173   while (swfdec_bits_left (&bits) >= 22) {
 174     buffer = swfdec_audio_decoder_adpcm_decode_chunk (&bits, n_bits, channels, granularity);
 175     if (buffer)
 176       swfdec_buffer_queue_push (adpcm->queue, buffer);
 177   }
 178 }
 179
 180 static SwfdecBuffer *
 181 swfdec_audio_decoder_adpcm_pull (SwfdecAudioDecoder *dec)
 182 {
 183   SwfdecAudioDecoderAdpcm *adpcm = (SwfdecAudioDecoderAdpcm *) dec;
 184
 185   return swfdec_buffer_queue_pull_buffer (adpcm->queue);
 186 }
 187
 188 static void
 189 swfdec_audio_decoder_adpcm_dispose (GObject *object)
 190 {
 191   SwfdecAudioDecoderAdpcm *dec = (SwfdecAudioDecoderAdpcm *) object;
 192
 193   swfdec_buffer_queue_unref (dec->queue);
 194
 195   G_OBJECT_CLASS (swfdec_audio_decoder_adpcm_parent_class)->dispose (object);
 196 }
 197
 198 static void
 199 swfdec_audio_decoder_adpcm_class_init (SwfdecAudioDecoderAdpcmClass *klass)
 200 {
 201   GObjectClass *object_class = G_OBJECT_CLASS (klass);
 202   SwfdecAudioDecoderClass *decoder_class = SWFDEC_AUDIO_DECODER_CLASS (klass);
 203
 204   object_class->dispose = swfdec_audio_decoder_adpcm_dispose;
 205
 206   decoder_class->prepare = swfdec_audio_decoder_adpcm_prepare;
 207   decoder_class->create = swfdec_audio_decoder_adpcm_create;
 208   decoder_class->pull = swfdec_audio_decoder_adpcm_pull;
 209   decoder_class->push = swfdec_audio_decoder_adpcm_push;
 210 }
 211
 212 static void
 213 swfdec_audio_decoder_adpcm_init (SwfdecAudioDecoderAdpcm *dec)
 214 {
 215   dec->queue = swfdec_buffer_queue_new ();
 216 }
 217