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ra144dec.c
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1 /*
2  * Real Audio 1.0 (14.4K)
3  *
4  * Copyright (c) 2008 Vitor Sessak
5  * Copyright (c) 2003 Nick Kurshev
6  * Based on public domain decoder at http://www.honeypot.net/audio
7  *
8  * This file is part of FFmpeg.
9  *
10  * FFmpeg is free software; you can redistribute it and/or
11  * modify it under the terms of the GNU Lesser General Public
12  * License as published by the Free Software Foundation; either
13  * version 2.1 of the License, or (at your option) any later version.
14  *
15  * FFmpeg is distributed in the hope that it will be useful,
16  * but WITHOUT ANY WARRANTY; without even the implied warranty of
17  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
18  * Lesser General Public License for more details.
19  *
20  * You should have received a copy of the GNU Lesser General Public
21  * License along with FFmpeg; if not, write to the Free Software
22  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
23  */
24 
26 #include "avcodec.h"
27 #include "get_bits.h"
28 #include "internal.h"
29 #include "ra144.h"
30 
31 
33 {
34  RA144Context *ractx = avctx->priv_data;
35 
36  ractx->avctx = avctx;
37 
38  ractx->lpc_coef[0] = ractx->lpc_tables[0];
39  ractx->lpc_coef[1] = ractx->lpc_tables[1];
40 
41  avctx->channels = 1;
44 
45  return 0;
46 }
47 
48 static void do_output_subblock(RA144Context *ractx, const int16_t *lpc_coefs,
49  int gval, GetBitContext *gb)
50 {
51  int cba_idx = get_bits(gb, 7); // index of the adaptive CB, 0 if none
52  int gain = get_bits(gb, 8);
53  int cb1_idx = get_bits(gb, 7);
54  int cb2_idx = get_bits(gb, 7);
55 
56  ff_subblock_synthesis(ractx, lpc_coefs, cba_idx, cb1_idx, cb2_idx, gval,
57  gain);
58 }
59 
60 /** Uncompress one block (20 bytes -> 160*2 bytes). */
61 static int ra144_decode_frame(AVCodecContext * avctx, void *data,
62  int *got_frame_ptr, AVPacket *avpkt)
63 {
64  AVFrame *frame = data;
65  const uint8_t *buf = avpkt->data;
66  int buf_size = avpkt->size;
67  static const uint8_t sizes[LPC_ORDER] = {6, 5, 5, 4, 4, 3, 3, 3, 3, 2};
68  unsigned int refl_rms[NBLOCKS]; // RMS of the reflection coefficients
69  int16_t block_coefs[NBLOCKS][LPC_ORDER]; // LPC coefficients of each sub-block
70  unsigned int lpc_refl[LPC_ORDER]; // LPC reflection coefficients of the frame
71  int i, j;
72  int ret;
73  int16_t *samples;
74  unsigned int energy;
75 
76  RA144Context *ractx = avctx->priv_data;
77  GetBitContext gb;
78 
79  if (buf_size < FRAME_SIZE) {
80  av_log(avctx, AV_LOG_ERROR,
81  "Frame too small (%d bytes). Truncated file?\n", buf_size);
82  *got_frame_ptr = 0;
83  return AVERROR_INVALIDDATA;
84  }
85 
86  /* get output buffer */
87  frame->nb_samples = NBLOCKS * BLOCKSIZE;
88  if ((ret = ff_get_buffer(avctx, frame, 0)) < 0)
89  return ret;
90  samples = (int16_t *)frame->data[0];
91 
92  init_get_bits(&gb, buf, FRAME_SIZE * 8);
93 
94  for (i = 0; i < LPC_ORDER; i++)
95  lpc_refl[i] = ff_lpc_refl_cb[i][get_bits(&gb, sizes[i])];
96 
97  ff_eval_coefs(ractx->lpc_coef[0], lpc_refl);
98  ractx->lpc_refl_rms[0] = ff_rms(lpc_refl);
99 
100  energy = ff_energy_tab[get_bits(&gb, 5)];
101 
102  refl_rms[0] = ff_interp(ractx, block_coefs[0], 1, 1, ractx->old_energy);
103  refl_rms[1] = ff_interp(ractx, block_coefs[1], 2,
104  energy <= ractx->old_energy,
105  ff_t_sqrt(energy*ractx->old_energy) >> 12);
106  refl_rms[2] = ff_interp(ractx, block_coefs[2], 3, 0, energy);
107  refl_rms[3] = ff_rescale_rms(ractx->lpc_refl_rms[0], energy);
108 
109  ff_int_to_int16(block_coefs[3], ractx->lpc_coef[0]);
110 
111  for (i=0; i < NBLOCKS; i++) {
112  do_output_subblock(ractx, block_coefs[i], refl_rms[i], &gb);
113 
114  for (j=0; j < BLOCKSIZE; j++)
115  *samples++ = av_clip_int16(ractx->curr_sblock[j + 10] << 2);
116  }
117 
118  ractx->old_energy = energy;
119  ractx->lpc_refl_rms[1] = ractx->lpc_refl_rms[0];
120 
121  FFSWAP(unsigned int *, ractx->lpc_coef[0], ractx->lpc_coef[1]);
122 
123  *got_frame_ptr = 1;
124 
125  return FRAME_SIZE;
126 }
127 
129  .name = "real_144",
130  .type = AVMEDIA_TYPE_AUDIO,
131  .id = AV_CODEC_ID_RA_144,
132  .priv_data_size = sizeof(RA144Context),
135  .capabilities = CODEC_CAP_DR1,
136  .long_name = NULL_IF_CONFIG_SMALL("RealAudio 1.0 (14.4K)"),
137 };