/* Swfdec * Copyright (C) 2006-2008 Benjamin Otte * * This library is free software; you can redistribute it and/or * modify it under the terms of the GNU Lesser General Public * License as published by the Free Software Foundation; either * version 2.1 of the License, or (at your option) any later version. * * This library is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU * Lesser General Public License for more details. * * You should have received a copy of the GNU Lesser General Public * License along with this library; if not, write to the Free Software * Foundation, Inc., 51 Franklin Street, Fifth Floor, * Boston, MA 02110-1301 USA */ #ifdef HAVE_CONFIG_H #include "config.h" #endif #include "swfdec_audio_decoder_adpcm.h" #include "swfdec_debug.h" #include "swfdec_internal.h" G_DEFINE_TYPE (SwfdecAudioDecoderAdpcm, swfdec_audio_decoder_adpcm, SWFDEC_TYPE_AUDIO_DECODER) static gboolean swfdec_audio_decoder_adpcm_prepare (guint codec, SwfdecAudioFormat format, char **missing) { return codec == SWFDEC_AUDIO_CODEC_ADPCM; } static SwfdecAudioDecoder * swfdec_audio_decoder_adpcm_create (guint codec, SwfdecAudioFormat format) { if (codec != SWFDEC_AUDIO_CODEC_ADPCM) return NULL; return g_object_new (SWFDEC_TYPE_AUDIO_DECODER_ADPCM, NULL); } static const int indexTable[4][16] = { { -1, 2 }, { -1, -1, 2, 4 }, { -1, -1, -1, -1, 2, 4, 6, 8 }, { -1, -1, -1, -1, -1, -1, -1, -1, 1, 2, 4, 6, 8, 10, 13, 16 } }; static const int stepSizeTable[89] = { 7, 8, 9, 10, 11, 12, 13, 14, 16, 17, 19, 21, 23, 25, 28, 31, 34, 37, 41, 45, 50, 55, 60, 66, 73, 80, 88, 97, 107, 118, 130, 143, 157, 173, 190, 209, 230, 253, 279, 307, 337, 371, 408, 449, 494, 544, 598, 658, 724, 796, 876, 963, 1060, 1166, 1282, 1411, 1552, 1707, 1878, 2066, 2272, 2499, 2749, 3024, 3327, 3660, 4026, 4428, 4871, 5358, 5894, 6484, 7132, 7845, 8630, 9493, 10442, 11487, 12635, 13899, 15289, 16818, 18500, 20350, 22385, 24623, 27086, 29794, 32767 }; static SwfdecBuffer * swfdec_audio_decoder_adpcm_decode_chunk (SwfdecBits *bits, guint n_bits, guint channels, guint granularity) { SwfdecBuffer *ret; guint len, repeat; guint i, j, ch; guint index[2]; int pred[2]; gint16 *out; guint delta, sign, sign_mask; int diff; const int *realIndexTable; guint step[2]; /* for scaling up the audio to 44100kHz */ repeat = 2 * granularity - channels; realIndexTable = indexTable[n_bits - 2]; for (ch = 0; ch < channels; ch++) { /* can't use get_s16 here since that would be aligned */ pred[ch] = swfdec_bits_getsbits (bits, 16); index[ch] = swfdec_bits_getbits (bits, 6); if (index[ch] >= G_N_ELEMENTS (stepSizeTable)) { SWFDEC_ERROR ("initial index too big: %u, max allowed is %td", index[ch], G_N_ELEMENTS (stepSizeTable) - 1); index[ch] = G_N_ELEMENTS (stepSizeTable) - 1; } step[ch] = stepSizeTable[index[ch]]; } len = swfdec_bits_left (bits) / channels / n_bits; len = MIN (len, 4095); ret = swfdec_buffer_new ((len + 1) * sizeof (gint16) * granularity * 2); out = (gint16 *) (void *) ret->data; /* output initial value */ SWFDEC_LOG ("decoding %u samples", len + 1); for (ch = 0; ch < channels; ch++) *out++ = pred[ch]; /* upscale to 44.1kHz */ for (ch = 0; ch < repeat; ch++) { *out = out[-(gssize) channels]; out++; } sign_mask = 1 << (n_bits - 1); for (i = 0; i < len; i++) { for (ch = 0; ch < channels; ch++) { /* Step 1 - get the delta value */ delta = swfdec_bits_getbits (bits, n_bits); /* Step 2 - Separate sign and magnitude */ sign = delta & sign_mask; delta -= sign; /* Step 3 - Find new index value (for later) */ index[ch] += realIndexTable[delta]; if ( index[ch] >= G_MAXINT ) index[ch] = 0; /* underflow */ if ( index[ch] >= G_N_ELEMENTS (stepSizeTable) ) index[ch] = G_N_ELEMENTS (stepSizeTable) - 1; /* Step 4 - Compute difference and new predicted value */ j = n_bits - 1; diff = step[ch] >> j; do { j--; if (delta & 1) diff += step[ch] >> j; delta >>= 1; } while (j > 0 && delta); if ( sign ) pred[ch] -= diff; else pred[ch] += diff; /* Step 5 - clamp output value */ pred[ch] = CLAMP (pred[ch], -32768, 32767); /* Step 6 - Update step value */ step[ch] = stepSizeTable[index[ch]]; /* Step 7 - Output value */ *out++ = pred[ch]; } /* upscale to 44.1kHz */ for (ch = 0; ch < repeat; ch++) { *out = out[-(gssize) channels]; out++; } } return ret; } static void swfdec_audio_decoder_adpcm_push (SwfdecAudioDecoder *dec, SwfdecBuffer *buffer) { SwfdecAudioDecoderAdpcm *adpcm = (SwfdecAudioDecoderAdpcm *) dec; guint channels, n_bits, granularity; SwfdecBits bits; if (buffer == NULL) return; channels = swfdec_audio_format_get_channels (dec->format); granularity = swfdec_audio_format_get_granularity (dec->format); swfdec_bits_init (&bits, buffer); n_bits = swfdec_bits_getbits (&bits, 2) + 2; SWFDEC_DEBUG ("starting decoding: %u channels, %u bits", channels, n_bits); /* 22 is minimum required header size */ while (swfdec_bits_left (&bits) >= 22) { buffer = swfdec_audio_decoder_adpcm_decode_chunk (&bits, n_bits, channels, granularity); if (buffer) swfdec_buffer_queue_push (adpcm->queue, buffer); } } static SwfdecBuffer * swfdec_audio_decoder_adpcm_pull (SwfdecAudioDecoder *dec) { SwfdecAudioDecoderAdpcm *adpcm = (SwfdecAudioDecoderAdpcm *) dec; return swfdec_buffer_queue_pull_buffer (adpcm->queue); } static void swfdec_audio_decoder_adpcm_dispose (GObject *object) { SwfdecAudioDecoderAdpcm *dec = (SwfdecAudioDecoderAdpcm *) object; swfdec_buffer_queue_unref (dec->queue); G_OBJECT_CLASS (swfdec_audio_decoder_adpcm_parent_class)->dispose (object); } static void swfdec_audio_decoder_adpcm_class_init (SwfdecAudioDecoderAdpcmClass *klass) { GObjectClass *object_class = G_OBJECT_CLASS (klass); SwfdecAudioDecoderClass *decoder_class = SWFDEC_AUDIO_DECODER_CLASS (klass); object_class->dispose = swfdec_audio_decoder_adpcm_dispose; decoder_class->prepare = swfdec_audio_decoder_adpcm_prepare; decoder_class->create = swfdec_audio_decoder_adpcm_create; decoder_class->pull = swfdec_audio_decoder_adpcm_pull; decoder_class->push = swfdec_audio_decoder_adpcm_push; } static void swfdec_audio_decoder_adpcm_init (SwfdecAudioDecoderAdpcm *dec) { dec->queue = swfdec_buffer_queue_new (); }