8svx.c
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1 /*
2  * 8SVX audio decoder
3  * Copyright (C) 2008 Jaikrishnan Menon
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 
31 #include "avcodec.h"
32 
34 typedef struct EightSvxContext {
36  uint8_t fib_acc[2];
37  const int8_t *table;
38 
39  /* buffer used to store the whole first packet.
40  data is only sent as one large packet */
41  uint8_t *data[2];
42  int data_size;
43  int data_idx;
45 
46 static const int8_t fibonacci[16] = { -34, -21, -13, -8, -5, -3, -2, -1,
47  0, 1, 2, 3, 5, 8, 13, 21 };
48 static const int8_t exponential[16] = { -128, -64, -32, -16, -8, -4, -2, -1,
49  0, 1, 2, 4, 8, 16, 32, 64 };
50 
51 #define MAX_FRAME_SIZE 32768
52 
59 static void delta_decode(uint8_t *dst, const uint8_t *src, int src_size,
60  uint8_t *state, const int8_t *table, int channels)
61 {
62  uint8_t val = *state;
63 
64  while (src_size--) {
65  uint8_t d = *src++;
66  val = av_clip_uint8(val + table[d & 0xF]);
67  *dst = val;
68  dst += channels;
69  val = av_clip_uint8(val + table[d >> 4]);
70  *dst = val;
71  dst += channels;
72  }
73 
74  *state = val;
75 }
76 
77 static void raw_decode(uint8_t *dst, const int8_t *src, int src_size,
78  int channels)
79 {
80  while (src_size--) {
81  *dst = *src++ + 128;
82  dst += channels;
83  }
84 }
85 
87 static int eightsvx_decode_frame(AVCodecContext *avctx, void *data,
88  int *got_frame_ptr, AVPacket *avpkt)
89 {
90  EightSvxContext *esc = avctx->priv_data;
91  int buf_size;
92  uint8_t *out_data;
93  int ret;
94  int is_compr = (avctx->codec_id != CODEC_ID_PCM_S8_PLANAR);
95 
96  /* for the first packet, copy data to buffer */
97  if (avpkt->data) {
98  int hdr_size = is_compr ? 2 : 0;
99  int chan_size = (avpkt->size - hdr_size * avctx->channels) / avctx->channels;
100 
101  if (avpkt->size < hdr_size * avctx->channels) {
102  av_log(avctx, AV_LOG_ERROR, "packet size is too small\n");
103  return AVERROR(EINVAL);
104  }
105  if (esc->data[0]) {
106  av_log(avctx, AV_LOG_ERROR, "unexpected data after first packet\n");
107  return AVERROR(EINVAL);
108  }
109 
110  if (is_compr) {
111  esc->fib_acc[0] = avpkt->data[1] + 128;
112  if (avctx->channels == 2)
113  esc->fib_acc[1] = avpkt->data[2+chan_size+1] + 128;
114  }
115 
116  esc->data_idx = 0;
117  esc->data_size = chan_size;
118  if (!(esc->data[0] = av_malloc(chan_size)))
119  return AVERROR(ENOMEM);
120  if (avctx->channels == 2) {
121  if (!(esc->data[1] = av_malloc(chan_size))) {
122  av_freep(&esc->data[0]);
123  return AVERROR(ENOMEM);
124  }
125  }
126  memcpy(esc->data[0], &avpkt->data[hdr_size], chan_size);
127  if (avctx->channels == 2)
128  memcpy(esc->data[1], &avpkt->data[2*hdr_size+chan_size], chan_size);
129  }
130  if (!esc->data[0]) {
131  av_log(avctx, AV_LOG_ERROR, "unexpected empty packet\n");
132  return AVERROR(EINVAL);
133  }
134 
135  /* decode next piece of data from the buffer */
136  buf_size = FFMIN(MAX_FRAME_SIZE, esc->data_size - esc->data_idx);
137  if (buf_size <= 0) {
138  *got_frame_ptr = 0;
139  return avpkt->size;
140  }
141 
142  /* get output buffer */
143  esc->frame.nb_samples = buf_size * (is_compr + 1);
144  if ((ret = avctx->get_buffer(avctx, &esc->frame)) < 0) {
145  av_log(avctx, AV_LOG_ERROR, "get_buffer() failed\n");
146  return ret;
147  }
148  out_data = esc->frame.data[0];
149 
150  if (is_compr) {
151  delta_decode(out_data, &esc->data[0][esc->data_idx], buf_size,
152  &esc->fib_acc[0], esc->table, avctx->channels);
153  if (avctx->channels == 2) {
154  delta_decode(&out_data[1], &esc->data[1][esc->data_idx], buf_size,
155  &esc->fib_acc[1], esc->table, avctx->channels);
156  }
157  } else {
158  int ch;
159  for (ch = 0; ch < avctx->channels; ch++) {
160  raw_decode((int8_t *)&out_data[ch], &esc->data[ch][esc->data_idx],
161  buf_size, avctx->channels);
162  }
163  }
164  esc->data_idx += buf_size;
165 
166  *got_frame_ptr = 1;
167  *(AVFrame *)data = esc->frame;
168 
169  return avpkt->size;
170 }
171 
174 {
175  EightSvxContext *esc = avctx->priv_data;
176 
177  if (avctx->channels < 1 || avctx->channels > 2) {
178  av_log(avctx, AV_LOG_ERROR, "8SVX does not support more than 2 channels\n");
179  return AVERROR(EINVAL);
180  }
181 
182  switch(avctx->codec->id) {
183  case CODEC_ID_8SVX_FIB:
184  esc->table = fibonacci;
185  break;
186  case CODEC_ID_8SVX_EXP:
187  esc->table = exponential;
188  break;
190  break;
191  default:
192  return -1;
193  }
194  avctx->sample_fmt = AV_SAMPLE_FMT_U8;
195 
197  avctx->coded_frame = &esc->frame;
198 
199  return 0;
200 }
201 
203 {
204  EightSvxContext *esc = avctx->priv_data;
205 
206  av_freep(&esc->data[0]);
207  av_freep(&esc->data[1]);
208 
209  return 0;
210 }
211 
213  .name = "8svx_fib",
214  .type = AVMEDIA_TYPE_AUDIO,
215  .id = CODEC_ID_8SVX_FIB,
216  .priv_data_size = sizeof (EightSvxContext),
220  .capabilities = CODEC_CAP_DELAY | CODEC_CAP_DR1,
221  .long_name = NULL_IF_CONFIG_SMALL("8SVX fibonacci"),
222 };
223 
225  .name = "8svx_exp",
226  .type = AVMEDIA_TYPE_AUDIO,
227  .id = CODEC_ID_8SVX_EXP,
228  .priv_data_size = sizeof (EightSvxContext),
232  .capabilities = CODEC_CAP_DELAY | CODEC_CAP_DR1,
233  .long_name = NULL_IF_CONFIG_SMALL("8SVX exponential"),
234 };
235 
237  .name = "pcm_s8_planar",
238  .type = AVMEDIA_TYPE_AUDIO,
240  .priv_data_size = sizeof(EightSvxContext),
244  .capabilities = CODEC_CAP_DELAY | CODEC_CAP_DR1,
245  .long_name = NULL_IF_CONFIG_SMALL("PCM signed 8-bit planar"),
246 };