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adxdec.c
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1 /*
2  * ADX ADPCM codecs
3  * Copyright (c) 2001,2003 BERO
4  *
5  * This file is part of FFmpeg.
6  *
7  * FFmpeg is free software; you can redistribute it and/or
8  * modify it under the terms of the GNU Lesser General Public
9  * License as published by the Free Software Foundation; either
10  * version 2.1 of the License, or (at your option) any later version.
11  *
12  * FFmpeg is distributed in the hope that it will be useful,
13  * but WITHOUT ANY WARRANTY; without even the implied warranty of
14  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
15  * Lesser General Public License for more details.
16  *
17  * You should have received a copy of the GNU Lesser General Public
18  * License along with FFmpeg; if not, write to the Free Software
19  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
20  */
21 
22 #include "libavutil/intreadwrite.h"
23 #include "avcodec.h"
24 #include "adx.h"
25 #include "get_bits.h"
26 #include "internal.h"
27 
28 /**
29  * @file
30  * SEGA CRI adx codecs.
31  *
32  * Reference documents:
33  * http://ku-www.ss.titech.ac.jp/~yatsushi/adx.html
34  * adx2wav & wav2adx http://www.geocities.co.jp/Playtown/2004/
35  */
36 
38 {
39  ADXContext *c = avctx->priv_data;
40  int ret, header_size;
41 
42  if (avctx->extradata_size >= 24) {
43  if ((ret = avpriv_adx_decode_header(avctx, avctx->extradata,
44  avctx->extradata_size, &header_size,
45  c->coeff)) < 0) {
46  av_log(avctx, AV_LOG_ERROR, "error parsing ADX header\n");
47  return AVERROR_INVALIDDATA;
48  }
49  c->channels = avctx->channels;
50  c->header_parsed = 1;
51  }
52 
54 
55  return 0;
56 }
57 
58 /**
59  * Decode 32 samples from 18 bytes.
60  *
61  * A 16-bit scalar value is applied to 32 residuals, which then have a
62  * 2nd-order LPC filter applied to it to form the output signal for a single
63  * channel.
64  */
65 static int adx_decode(ADXContext *c, int16_t *out, int offset,
66  const uint8_t *in, int ch)
67 {
68  ADXChannelState *prev = &c->prev[ch];
69  GetBitContext gb;
70  int scale = AV_RB16(in);
71  int i;
72  int s0, s1, s2, d;
73 
74  /* check if this is an EOF packet */
75  if (scale & 0x8000)
76  return -1;
77 
78  init_get_bits(&gb, in + 2, (BLOCK_SIZE - 2) * 8);
79  out += offset;
80  s1 = prev->s1;
81  s2 = prev->s2;
82  for (i = 0; i < BLOCK_SAMPLES; i++) {
83  d = get_sbits(&gb, 4);
84  s0 = ((d << COEFF_BITS) * scale + c->coeff[0] * s1 + c->coeff[1] * s2) >> COEFF_BITS;
85  s2 = s1;
86  s1 = av_clip_int16(s0);
87  *out++ = s1;
88  }
89  prev->s1 = s1;
90  prev->s2 = s2;
91 
92  return 0;
93 }
94 
95 static int adx_decode_frame(AVCodecContext *avctx, void *data,
96  int *got_frame_ptr, AVPacket *avpkt)
97 {
98  AVFrame *frame = data;
99  int buf_size = avpkt->size;
100  ADXContext *c = avctx->priv_data;
101  int16_t **samples;
102  int samples_offset;
103  const uint8_t *buf = avpkt->data;
104  const uint8_t *buf_end = buf + avpkt->size;
105  int num_blocks, ch, ret;
106 
107  if (c->eof) {
108  *got_frame_ptr = 0;
109  return buf_size;
110  }
111 
112  if (!c->header_parsed && buf_size >= 2 && AV_RB16(buf) == 0x8000) {
113  int header_size;
114  if ((ret = avpriv_adx_decode_header(avctx, buf, buf_size, &header_size,
115  c->coeff)) < 0) {
116  av_log(avctx, AV_LOG_ERROR, "error parsing ADX header\n");
117  return AVERROR_INVALIDDATA;
118  }
119  c->channels = avctx->channels;
120  c->header_parsed = 1;
121  if (buf_size < header_size)
122  return AVERROR_INVALIDDATA;
123  buf += header_size;
124  buf_size -= header_size;
125  }
126  if (!c->header_parsed)
127  return AVERROR_INVALIDDATA;
128 
129  /* calculate number of blocks in the packet */
130  num_blocks = buf_size / (BLOCK_SIZE * c->channels);
131 
132  /* if the packet is not an even multiple of BLOCK_SIZE, check for an EOF
133  packet */
134  if (!num_blocks || buf_size % (BLOCK_SIZE * avctx->channels)) {
135  if (buf_size >= 4 && (AV_RB16(buf) & 0x8000)) {
136  c->eof = 1;
137  *got_frame_ptr = 0;
138  return avpkt->size;
139  }
140  return AVERROR_INVALIDDATA;
141  }
142 
143  /* get output buffer */
144  frame->nb_samples = num_blocks * BLOCK_SAMPLES;
145  if ((ret = ff_get_buffer(avctx, frame, 0)) < 0)
146  return ret;
147  samples = (int16_t **)frame->extended_data;
148  samples_offset = 0;
149 
150  while (num_blocks--) {
151  for (ch = 0; ch < c->channels; ch++) {
152  if (buf_end - buf < BLOCK_SIZE || adx_decode(c, samples[ch], samples_offset, buf, ch)) {
153  c->eof = 1;
154  buf = avpkt->data + avpkt->size;
155  break;
156  }
157  buf_size -= BLOCK_SIZE;
158  buf += BLOCK_SIZE;
159  }
160  samples_offset += BLOCK_SAMPLES;
161  }
162 
163  *got_frame_ptr = 1;
164 
165  return buf - avpkt->data;
166 }
167 
168 static void adx_decode_flush(AVCodecContext *avctx)
169 {
170  ADXContext *c = avctx->priv_data;
171  memset(c->prev, 0, sizeof(c->prev));
172  c->eof = 0;
173 }
174 
176  .name = "adpcm_adx",
177  .long_name = NULL_IF_CONFIG_SMALL("SEGA CRI ADX ADPCM"),
178  .type = AVMEDIA_TYPE_AUDIO,
179  .id = AV_CODEC_ID_ADPCM_ADX,
180  .priv_data_size = sizeof(ADXContext),
184  .capabilities = CODEC_CAP_DR1,
185  .sample_fmts = (const enum AVSampleFormat[]) { AV_SAMPLE_FMT_S16P,
187 };