adxdec.c
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1 /*
2  * ADX ADPCM codecs
3  * Copyright (c) 2001,2003 BERO
4  *
5  * This file is part of Libav.
6  *
7  * Libav 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  * Libav 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 Libav; 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 
37 {
38  ADXContext *c = avctx->priv_data;
39  int ret, header_size;
40 
41  if (avctx->extradata_size >= 24) {
42  if ((ret = avpriv_adx_decode_header(avctx, avctx->extradata,
43  avctx->extradata_size, &header_size,
44  c->coeff)) < 0) {
45  av_log(avctx, AV_LOG_ERROR, "error parsing ADX header\n");
46  return AVERROR_INVALIDDATA;
47  }
48  c->channels = avctx->channels;
49  c->header_parsed = 1;
50  }
51 
53 
55  avctx->coded_frame = &c->frame;
56 
57  return 0;
58 }
59 
67 static int adx_decode(ADXContext *c, int16_t *out, const uint8_t *in, int ch)
68 {
69  ADXChannelState *prev = &c->prev[ch];
70  GetBitContext gb;
71  int scale = AV_RB16(in);
72  int i;
73  int s0, s1, s2, d;
74 
75  /* check if this is an EOF packet */
76  if (scale & 0x8000)
77  return -1;
78 
79  init_get_bits(&gb, in + 2, (BLOCK_SIZE - 2) * 8);
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  out += c->channels;
89  }
90  prev->s1 = s1;
91  prev->s2 = s2;
92 
93  return 0;
94 }
95 
96 static int adx_decode_frame(AVCodecContext *avctx, void *data,
97  int *got_frame_ptr, AVPacket *avpkt)
98 {
99  int buf_size = avpkt->size;
100  ADXContext *c = avctx->priv_data;
101  int16_t *samples;
102  const uint8_t *buf = avpkt->data;
103  int num_blocks, ch, ret;
104 
105  if (c->eof) {
106  *got_frame_ptr = 0;
107  return buf_size;
108  }
109 
110  if (!c->header_parsed && buf_size >= 2 && AV_RB16(buf) == 0x8000) {
111  int header_size;
112  if ((ret = avpriv_adx_decode_header(avctx, buf, buf_size, &header_size,
113  c->coeff)) < 0) {
114  av_log(avctx, AV_LOG_ERROR, "error parsing ADX header\n");
115  return AVERROR_INVALIDDATA;
116  }
117  c->channels = avctx->channels;
118  c->header_parsed = 1;
119  if (buf_size < header_size)
120  return AVERROR_INVALIDDATA;
121  buf += header_size;
122  buf_size -= header_size;
123  }
124  if (!c->header_parsed)
125  return AVERROR_INVALIDDATA;
126 
127  /* calculate number of blocks in the packet */
128  num_blocks = buf_size / (BLOCK_SIZE * c->channels);
129 
130  /* if the packet is not an even multiple of BLOCK_SIZE, check for an EOF
131  packet */
132  if (!num_blocks || buf_size % (BLOCK_SIZE * avctx->channels)) {
133  if (buf_size >= 4 && (AV_RB16(buf) & 0x8000)) {
134  c->eof = 1;
135  *got_frame_ptr = 0;
136  return avpkt->size;
137  }
138  return AVERROR_INVALIDDATA;
139  }
140 
141  /* get output buffer */
142  c->frame.nb_samples = num_blocks * BLOCK_SAMPLES;
143  if ((ret = avctx->get_buffer(avctx, &c->frame)) < 0) {
144  av_log(avctx, AV_LOG_ERROR, "get_buffer() failed\n");
145  return ret;
146  }
147  samples = (int16_t *)c->frame.data[0];
148 
149  while (num_blocks--) {
150  for (ch = 0; ch < c->channels; ch++) {
151  if (adx_decode(c, samples + ch, buf, ch)) {
152  c->eof = 1;
153  buf = avpkt->data + avpkt->size;
154  break;
155  }
156  buf_size -= BLOCK_SIZE;
157  buf += BLOCK_SIZE;
158  }
159  samples += BLOCK_SAMPLES * c->channels;
160  }
161 
162  *got_frame_ptr = 1;
163  *(AVFrame *)data = c->frame;
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  .type = AVMEDIA_TYPE_AUDIO,
178  .id = CODEC_ID_ADPCM_ADX,
179  .priv_data_size = sizeof(ADXContext),
183  .capabilities = CODEC_CAP_DR1,
184  .long_name = NULL_IF_CONFIG_SMALL("SEGA CRI ADX ADPCM"),
185 };