adxenc.c
Go to the documentation of this file.
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 "avcodec.h"
23 #include "adx.h"
24 #include "bytestream.h"
25 #include "put_bits.h"
26 
36 static void adx_encode(ADXContext *c, uint8_t *adx, const int16_t *wav,
37  ADXChannelState *prev, int channels)
38 {
39  PutBitContext pb;
40  int scale;
41  int i, j;
42  int s0, s1, s2, d;
43  int max = 0;
44  int min = 0;
45  int data[BLOCK_SAMPLES];
46 
47  s1 = prev->s1;
48  s2 = prev->s2;
49  for (i = 0, j = 0; j < 32; i += channels, j++) {
50  s0 = wav[i];
51  d = ((s0 << COEFF_BITS) - c->coeff[0] * s1 - c->coeff[1] * s2) >> COEFF_BITS;
52  data[j] = d;
53  if (max < d)
54  max = d;
55  if (min > d)
56  min = d;
57  s2 = s1;
58  s1 = s0;
59  }
60  prev->s1 = s1;
61  prev->s2 = s2;
62 
63  if (max == 0 && min == 0) {
64  memset(adx, 0, BLOCK_SIZE);
65  return;
66  }
67 
68  if (max / 7 > -min / 8)
69  scale = max / 7;
70  else
71  scale = -min / 8;
72 
73  if (scale == 0)
74  scale = 1;
75 
76  AV_WB16(adx, scale);
77 
78  init_put_bits(&pb, adx + 2, 16);
79  for (i = 0; i < BLOCK_SAMPLES; i++)
80  put_sbits(&pb, 4, av_clip(data[i] / scale, -8, 7));
81  flush_put_bits(&pb);
82 }
83 
84 #define HEADER_SIZE 36
85 
86 static int adx_encode_header(AVCodecContext *avctx, uint8_t *buf, int bufsize)
87 {
88  ADXContext *c = avctx->priv_data;
89 
90  if (bufsize < HEADER_SIZE)
91  return AVERROR(EINVAL);
92 
93  bytestream_put_be16(&buf, 0x8000); /* header signature */
94  bytestream_put_be16(&buf, HEADER_SIZE - 4); /* copyright offset */
95  bytestream_put_byte(&buf, 3); /* encoding */
96  bytestream_put_byte(&buf, BLOCK_SIZE); /* block size */
97  bytestream_put_byte(&buf, 4); /* sample size */
98  bytestream_put_byte(&buf, avctx->channels); /* channels */
99  bytestream_put_be32(&buf, avctx->sample_rate); /* sample rate */
100  bytestream_put_be32(&buf, 0); /* total sample count */
101  bytestream_put_be16(&buf, c->cutoff); /* cutoff frequency */
102  bytestream_put_byte(&buf, 3); /* version */
103  bytestream_put_byte(&buf, 0); /* flags */
104  bytestream_put_be32(&buf, 0); /* unknown */
105  bytestream_put_be32(&buf, 0); /* loop enabled */
106  bytestream_put_be16(&buf, 0); /* padding */
107  bytestream_put_buffer(&buf, "(c)CRI", 6); /* copyright signature */
108 
109  return HEADER_SIZE;
110 }
111 
113 {
114  ADXContext *c = avctx->priv_data;
115 
116  if (avctx->channels > 2) {
117  av_log(avctx, AV_LOG_ERROR, "Invalid number of channels\n");
118  return AVERROR(EINVAL);
119  }
120  avctx->frame_size = BLOCK_SAMPLES;
121 
122  avctx->coded_frame = avcodec_alloc_frame();
123 
124  /* the cutoff can be adjusted, but this seems to work pretty well */
125  c->cutoff = 500;
127 
128  return 0;
129 }
130 
132 {
133  av_freep(&avctx->coded_frame);
134  return 0;
135 }
136 
137 static int adx_encode_frame(AVCodecContext *avctx, uint8_t *frame,
138  int buf_size, void *data)
139 {
140  ADXContext *c = avctx->priv_data;
141  const int16_t *samples = data;
142  uint8_t *dst = frame;
143  int ch;
144 
145  if (!c->header_parsed) {
146  int hdrsize;
147  if ((hdrsize = adx_encode_header(avctx, dst, buf_size)) < 0) {
148  av_log(avctx, AV_LOG_ERROR, "output buffer is too small\n");
149  return AVERROR(EINVAL);
150  }
151  dst += hdrsize;
152  buf_size -= hdrsize;
153  c->header_parsed = 1;
154  }
155  if (buf_size < BLOCK_SIZE * avctx->channels) {
156  av_log(avctx, AV_LOG_ERROR, "output buffer is too small\n");
157  return AVERROR(EINVAL);
158  }
159 
160  for (ch = 0; ch < avctx->channels; ch++) {
161  adx_encode(c, dst, samples + ch, &c->prev[ch], avctx->channels);
162  dst += BLOCK_SIZE;
163  }
164  return dst - frame;
165 }
166 
168  .name = "adpcm_adx",
169  .type = AVMEDIA_TYPE_AUDIO,
170  .id = CODEC_ID_ADPCM_ADX,
171  .priv_data_size = sizeof(ADXContext),
173  .encode = adx_encode_frame,
175  .sample_fmts = (const enum AVSampleFormat[]) { AV_SAMPLE_FMT_S16,
177  .long_name = NULL_IF_CONFIG_SMALL("SEGA CRI ADX ADPCM"),
178 };