ws-snd1.c
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1 /*
2  * Westwood SNDx codecs
3  * Copyright (c) 2005 Konstantin Shishkov
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 <stdint.h>
23 #include "libavutil/intreadwrite.h"
24 #include "avcodec.h"
25 
35 static const int8_t ws_adpcm_4bit[] = {
36  -9, -8, -6, -5, -4, -3, -2, -1,
37  0, 1, 2, 3, 4, 5, 6, 8
38 };
39 
40 typedef struct WSSndContext {
42 } WSSndContext;
43 
45 {
46  WSSndContext *s = avctx->priv_data;
47 
48  if (avctx->channels != 1) {
49  av_log_ask_for_sample(avctx, "unsupported number of channels\n");
50  return AVERROR(EINVAL);
51  }
52 
54 
56  avctx->coded_frame = &s->frame;
57 
58  return 0;
59 }
60 
61 static int ws_snd_decode_frame(AVCodecContext *avctx, void *data,
62  int *got_frame_ptr, AVPacket *avpkt)
63 {
64  WSSndContext *s = avctx->priv_data;
65  const uint8_t *buf = avpkt->data;
66  int buf_size = avpkt->size;
67 
68  int in_size, out_size, ret;
69  int sample = 128;
70  uint8_t *samples;
71  uint8_t *samples_end;
72 
73  if (!buf_size)
74  return 0;
75 
76  if (buf_size < 4) {
77  av_log(avctx, AV_LOG_ERROR, "packet is too small\n");
78  return AVERROR(EINVAL);
79  }
80 
81  out_size = AV_RL16(&buf[0]);
82  in_size = AV_RL16(&buf[2]);
83  buf += 4;
84 
85  if (in_size > buf_size) {
86  av_log(avctx, AV_LOG_ERROR, "Frame data is larger than input buffer\n");
87  return -1;
88  }
89 
90  /* get output buffer */
91  s->frame.nb_samples = out_size;
92  if ((ret = avctx->get_buffer(avctx, &s->frame)) < 0) {
93  av_log(avctx, AV_LOG_ERROR, "get_buffer() failed\n");
94  return ret;
95  }
96  samples = s->frame.data[0];
97  samples_end = samples + out_size;
98 
99  if (in_size == out_size) {
100  memcpy(samples, buf, out_size);
101  *got_frame_ptr = 1;
102  *(AVFrame *)data = s->frame;
103  return buf_size;
104  }
105 
106  while (samples < samples_end && buf - avpkt->data < buf_size) {
107  int code, smp, size;
108  uint8_t count;
109  code = *buf >> 6;
110  count = *buf & 0x3F;
111  buf++;
112 
113  /* make sure we don't write past the output buffer */
114  switch (code) {
115  case 0: smp = 4*(count+1); break;
116  case 1: smp = 2*(count+1); break;
117  case 2: smp = (count & 0x20) ? 1 : count + 1; break;
118  default: smp = count + 1; break;
119  }
120  if (samples_end - samples < smp)
121  break;
122 
123  /* make sure we don't read past the input buffer */
124  size = ((code == 2 && (count & 0x20)) || code == 3) ? 0 : count + 1;
125  if ((buf - avpkt->data) + size > buf_size)
126  break;
127 
128  switch (code) {
129  case 0: /* ADPCM 2-bit */
130  for (count++; count > 0; count--) {
131  code = *buf++;
132  sample += ( code & 0x3) - 2;
133  sample = av_clip_uint8(sample);
134  *samples++ = sample;
135  sample += ((code >> 2) & 0x3) - 2;
136  sample = av_clip_uint8(sample);
137  *samples++ = sample;
138  sample += ((code >> 4) & 0x3) - 2;
139  sample = av_clip_uint8(sample);
140  *samples++ = sample;
141  sample += (code >> 6) - 2;
142  sample = av_clip_uint8(sample);
143  *samples++ = sample;
144  }
145  break;
146  case 1: /* ADPCM 4-bit */
147  for (count++; count > 0; count--) {
148  code = *buf++;
149  sample += ws_adpcm_4bit[code & 0xF];
150  sample = av_clip_uint8(sample);
151  *samples++ = sample;
152  sample += ws_adpcm_4bit[code >> 4];
153  sample = av_clip_uint8(sample);
154  *samples++ = sample;
155  }
156  break;
157  case 2: /* no compression */
158  if (count & 0x20) { /* big delta */
159  int8_t t;
160  t = count;
161  t <<= 3;
162  sample += t >> 3;
163  sample = av_clip_uint8(sample);
164  *samples++ = sample;
165  } else { /* copy */
166  memcpy(samples, buf, smp);
167  samples += smp;
168  buf += smp;
169  sample = buf[-1];
170  }
171  break;
172  default: /* run */
173  memset(samples, sample, smp);
174  samples += smp;
175  }
176  }
177 
178  s->frame.nb_samples = samples - s->frame.data[0];
179  *got_frame_ptr = 1;
180  *(AVFrame *)data = s->frame;
181 
182  return buf_size;
183 }
184 
186  .name = "ws_snd1",
187  .type = AVMEDIA_TYPE_AUDIO,
189  .priv_data_size = sizeof(WSSndContext),
192  .capabilities = CODEC_CAP_DR1,
193  .long_name = NULL_IF_CONFIG_SMALL("Westwood Audio (SND1)"),
194 };