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ttaenc.c
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1 /*
2  * TTA (The Lossless True Audio) encoder
3  *
4  * This file is part of FFmpeg.
5  *
6  * FFmpeg is free software; you can redistribute it and/or
7  * modify it under the terms of the GNU Lesser General Public
8  * License as published by the Free Software Foundation; either
9  * version 2.1 of the License, or (at your option) any later version.
10  *
11  * FFmpeg is distributed in the hope that it will be useful,
12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
14  * Lesser General Public License for more details.
15  *
16  * You should have received a copy of the GNU Lesser General Public
17  * License along with FFmpeg; if not, write to the Free Software
18  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
19  */
20 
21 #define BITSTREAM_WRITER_LE
22 #include "ttadata.h"
23 #include "avcodec.h"
24 #include "put_bits.h"
25 #include "internal.h"
26 #include "libavutil/crc.h"
27 
28 typedef struct TTAEncContext {
29  const AVCRC *crc_table;
30  int bps;
31  TTAChannel *ch_ctx;
32 } TTAEncContext;
33 
34 static av_cold int tta_encode_init(AVCodecContext *avctx)
35 {
36  TTAEncContext *s = avctx->priv_data;
37 
38  s->crc_table = av_crc_get_table(AV_CRC_32_IEEE_LE);
39 
40  switch (avctx->sample_fmt) {
41  case AV_SAMPLE_FMT_U8:
42  avctx->bits_per_raw_sample = 8;
43  break;
44  case AV_SAMPLE_FMT_S16:
45  avctx->bits_per_raw_sample = 16;
46  break;
47  case AV_SAMPLE_FMT_S32:
48  if (avctx->bits_per_raw_sample > 24)
49  av_log(avctx, AV_LOG_WARNING, "encoding as 24 bits-per-sample\n");
50  avctx->bits_per_raw_sample = 24;
51  }
52 
53  s->bps = avctx->bits_per_raw_sample >> 3;
54  avctx->frame_size = 256 * avctx->sample_rate / 245;
55 
56  s->ch_ctx = av_malloc(avctx->channels * sizeof(*s->ch_ctx));
57  if (!s->ch_ctx)
58  return AVERROR(ENOMEM);
59 
60  return 0;
61 }
62 
63 static inline void ttafilter_process(TTAFilter *c, int32_t *in)
64 {
65  register int32_t *dl = c->dl, *qm = c->qm, *dx = c->dx, sum = c->round;
66 
67  if (c->error < 0) {
68  qm[0] -= dx[0]; qm[1] -= dx[1]; qm[2] -= dx[2]; qm[3] -= dx[3];
69  qm[4] -= dx[4]; qm[5] -= dx[5]; qm[6] -= dx[6]; qm[7] -= dx[7];
70  } else if (c->error > 0) {
71  qm[0] += dx[0]; qm[1] += dx[1]; qm[2] += dx[2]; qm[3] += dx[3];
72  qm[4] += dx[4]; qm[5] += dx[5]; qm[6] += dx[6]; qm[7] += dx[7];
73  }
74 
75  sum += dl[0] * qm[0] + dl[1] * qm[1] + dl[2] * qm[2] + dl[3] * qm[3] +
76  dl[4] * qm[4] + dl[5] * qm[5] + dl[6] * qm[6] + dl[7] * qm[7];
77 
78  dx[0] = dx[1]; dx[1] = dx[2]; dx[2] = dx[3]; dx[3] = dx[4];
79  dl[0] = dl[1]; dl[1] = dl[2]; dl[2] = dl[3]; dl[3] = dl[4];
80 
81  dx[4] = ((dl[4] >> 30) | 1);
82  dx[5] = ((dl[5] >> 30) | 2) & ~1;
83  dx[6] = ((dl[6] >> 30) | 2) & ~1;
84  dx[7] = ((dl[7] >> 30) | 4) & ~3;
85 
86  dl[4] = -dl[5]; dl[5] = -dl[6];
87  dl[6] = *in - dl[7]; dl[7] = *in;
88  dl[5] += dl[6]; dl[4] += dl[5];
89 
90  *in -= (sum >> c->shift);
91  c->error = *in;
92 }
93 
94 static int32_t get_sample(const AVFrame *frame, int sample,
95  enum AVSampleFormat format)
96 {
97  int32_t ret;
98 
99  if (format == AV_SAMPLE_FMT_U8) {
100  ret = frame->data[0][sample] - 0x80;
101  } else if (format == AV_SAMPLE_FMT_S16) {
102  const int16_t *ptr = (const int16_t *)frame->data[0];
103  ret = ptr[sample];
104  } else {
105  const int32_t *ptr = (const int32_t *)frame->data[0];
106  ret = ptr[sample] >> 8;
107  }
108 
109  return ret;
110 }
111 
112 static int tta_encode_frame(AVCodecContext *avctx, AVPacket *avpkt,
113  const AVFrame *frame, int *got_packet_ptr)
114 {
115  TTAEncContext *s = avctx->priv_data;
116  PutBitContext pb;
117  int ret, i, out_bytes, cur_chan = 0, res = 0, samples = 0;
118 
119  if ((ret = ff_alloc_packet2(avctx, avpkt, frame->nb_samples * 2 * s->bps)) < 0)
120  return ret;
121  init_put_bits(&pb, avpkt->data, avpkt->size);
122 
123  // init per channel states
124  for (i = 0; i < avctx->channels; i++) {
125  s->ch_ctx[i].predictor = 0;
126  ff_tta_filter_init(&s->ch_ctx[i].filter, ff_tta_filter_configs[s->bps - 1]);
127  ff_tta_rice_init(&s->ch_ctx[i].rice, 10, 10);
128  }
129 
130  for (i = 0; i < frame->nb_samples * avctx->channels; i++) {
131  TTAChannel *c = &s->ch_ctx[cur_chan];
132  TTAFilter *filter = &c->filter;
133  TTARice *rice = &c->rice;
134  uint32_t k, unary, outval;
135  int32_t value, temp;
136 
137  value = get_sample(frame, samples++, avctx->sample_fmt);
138 
139  if (avctx->channels > 1) {
140  if (cur_chan < avctx->channels - 1)
141  value = res = get_sample(frame, samples, avctx->sample_fmt) - value;
142  else
143  value -= res / 2;
144  }
145 
146  temp = value;
147 #define PRED(x, k) (int32_t)((((uint64_t)x << k) - x) >> k)
148  switch (s->bps) {
149  case 1: value -= PRED(c->predictor, 4); break;
150  case 2:
151  case 3: value -= PRED(c->predictor, 5); break;
152  }
153  c->predictor = temp;
154 
155  ttafilter_process(filter, &value);
156  outval = (value > 0) ? (value << 1) - 1: -value << 1;
157 
158  k = rice->k0;
159 
160  rice->sum0 += outval - (rice->sum0 >> 4);
161  if (rice->k0 > 0 && rice->sum0 < ff_tta_shift_16[rice->k0])
162  rice->k0--;
163  else if (rice->sum0 > ff_tta_shift_16[rice->k0 + 1])
164  rice->k0++;
165 
166  if (outval >= ff_tta_shift_1[k]) {
167  outval -= ff_tta_shift_1[k];
168  k = rice->k1;
169 
170  rice->sum1 += outval - (rice->sum1 >> 4);
171  if (rice->k1 > 0 && rice->sum1 < ff_tta_shift_16[rice->k1])
172  rice->k1--;
173  else if (rice->sum1 > ff_tta_shift_16[rice->k1 + 1])
174  rice->k1++;
175 
176  unary = 1 + (outval >> k);
177  do {
178  if (unary > 31) {
179  put_bits(&pb, 31, 0x7FFFFFFF);
180  unary -= 31;
181  } else {
182  put_bits(&pb, unary, (1 << unary) - 1);
183  unary = 0;
184  }
185  } while (unary);
186  }
187 
188  put_bits(&pb, 1, 0);
189 
190  if (k)
191  put_bits(&pb, k, outval & (ff_tta_shift_1[k] - 1));
192 
193  if (cur_chan < avctx->channels - 1)
194  cur_chan++;
195  else
196  cur_chan = 0;
197  }
198 
199  flush_put_bits(&pb);
200  out_bytes = put_bits_count(&pb) >> 3;
201  put_bits32(&pb, av_crc(s->crc_table, UINT32_MAX, avpkt->data, out_bytes) ^ UINT32_MAX);
202  flush_put_bits(&pb);
203 
204  avpkt->pts = frame->pts;
205  avpkt->size = out_bytes + 4;
206  avpkt->duration = ff_samples_to_time_base(avctx, frame->nb_samples);
207  *got_packet_ptr = 1;
208  return 0;
209 }
210 
211 static av_cold int tta_encode_close(AVCodecContext *avctx)
212 {
213  TTAEncContext *s = avctx->priv_data;
214  av_freep(&s->ch_ctx);
215  return 0;
216 }
217 
218 AVCodec ff_tta_encoder = {
219  .name = "tta",
220  .type = AVMEDIA_TYPE_AUDIO,
221  .id = AV_CODEC_ID_TTA,
222  .priv_data_size = sizeof(TTAEncContext),
223  .init = tta_encode_init,
224  .close = tta_encode_close,
225  .encode2 = tta_encode_frame,
226  .capabilities = CODEC_CAP_SMALL_LAST_FRAME | CODEC_CAP_LOSSLESS,
227  .sample_fmts = (const enum AVSampleFormat[]){ AV_SAMPLE_FMT_U8,
228  AV_SAMPLE_FMT_S16,
229  AV_SAMPLE_FMT_S32,
230  AV_SAMPLE_FMT_NONE },
231  .long_name = NULL_IF_CONFIG_SMALL("TTA (True Audio)"),
232 };
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