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s302menc.c
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1 /*
2  * SMPTE 302M encoder
3  * Copyright (c) 2010 Google, Inc.
4  * Copyright (c) 2013 Darryl Wallace <wallacdj@gmail.com>
5  *
6  * This file is part of FFmpeg.
7  *
8  * FFmpeg is free software; you can redistribute it and/or
9  * modify it under the terms of the GNU Lesser General Public
10  * License as published by the Free Software Foundation; either
11  * version 2.1 of the License, or (at your option) any later version.
12  *
13  * FFmpeg is distributed in the hope that it will be useful,
14  * but WITHOUT ANY WARRANTY; without even the implied warranty of
15  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
16  * Lesser General Public License for more details.
17  *
18  * You should have received a copy of the GNU Lesser General Public
19  * License along with FFmpeg; if not, write to the Free Software
20  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
21  */
22 
23 #include "avcodec.h"
24 #include "internal.h"
25 #include "mathops.h"
26 #include "put_bits.h"
27 
28 #define AES3_HEADER_LEN 4
29 
30 typedef struct S302MEncContext {
31  uint8_t framing_index; /* Set for even channels on multiple of 192 samples */
33 
35 {
36  S302MEncContext *s = avctx->priv_data;
37 
38  if (avctx->channels & 1 || avctx->channels > 8) {
39  av_log(avctx, AV_LOG_ERROR,
40  "Encoding %d channel(s) is not allowed. Only 2, 4, 6 and 8 channels are supported.\n",
41  avctx->channels);
42  return AVERROR(EINVAL);
43  }
44 
45  switch (avctx->sample_fmt) {
46  case AV_SAMPLE_FMT_S16:
47  avctx->bits_per_raw_sample = 16;
48  break;
49  case AV_SAMPLE_FMT_S32:
50  if (avctx->bits_per_raw_sample > 20) {
51  if (avctx->bits_per_raw_sample > 24)
52  av_log(avctx, AV_LOG_WARNING, "encoding as 24 bits-per-sample\n");
53  avctx->bits_per_raw_sample = 24;
54  } else if (!avctx->bits_per_raw_sample) {
55  avctx->bits_per_raw_sample = 24;
56  } else if (avctx->bits_per_raw_sample <= 20) {
57  avctx->bits_per_raw_sample = 20;
58  }
59  }
60 
61  avctx->frame_size = 0;
62  avctx->bit_rate = 48000 * avctx->channels *
63  (avctx->bits_per_raw_sample + 4);
64  s->framing_index = 0;
65 
66  return 0;
67 }
68 
69 static int s302m_encode2_frame(AVCodecContext *avctx, AVPacket *avpkt,
70  const AVFrame *frame, int *got_packet_ptr)
71 {
72  S302MEncContext *s = avctx->priv_data;
73  const int buf_size = AES3_HEADER_LEN +
74  (frame->nb_samples *
75  avctx->channels *
76  (avctx->bits_per_raw_sample + 4)) / 8;
77  int ret, c, channels;
78  uint8_t *o;
79  PutBitContext pb;
80 
81  if ((ret = ff_alloc_packet2(avctx, avpkt, buf_size)) < 0)
82  return ret;
83 
84  o = avpkt->data;
85  init_put_bits(&pb, o, buf_size);
86  put_bits(&pb, 16, buf_size - AES3_HEADER_LEN);
87  put_bits(&pb, 2, (avctx->channels - 2) >> 1); // number of channels
88  put_bits(&pb, 8, 0); // channel ID
89  put_bits(&pb, 2, (avctx->bits_per_raw_sample - 16) / 4); // bits per samples (0 = 16bit, 1 = 20bit, 2 = 24bit)
90  put_bits(&pb, 4, 0); // alignments
91  flush_put_bits(&pb);
92  o += AES3_HEADER_LEN;
93 
94  if (avctx->bits_per_raw_sample == 24) {
95  const uint32_t *samples = (uint32_t *)frame->data[0];
96 
97  for (c = 0; c < frame->nb_samples; c++) {
98  uint8_t vucf = s->framing_index == 0 ? 0x10: 0;
99 
100  for (channels = 0; channels < avctx->channels; channels += 2) {
101  o[0] = ff_reverse[(samples[0] & 0x0000FF00) >> 8];
102  o[1] = ff_reverse[(samples[0] & 0x00FF0000) >> 16];
103  o[2] = ff_reverse[(samples[0] & 0xFF000000) >> 24];
104  o[3] = ff_reverse[(samples[1] & 0x00000F00) >> 4] | vucf;
105  o[4] = ff_reverse[(samples[1] & 0x000FF000) >> 12];
106  o[5] = ff_reverse[(samples[1] & 0x0FF00000) >> 20];
107  o[6] = ff_reverse[(samples[1] & 0xF0000000) >> 28];
108  o += 7;
109  samples += 2;
110  }
111 
112  s->framing_index++;
113  if (s->framing_index >= 192)
114  s->framing_index = 0;
115  }
116  } else if (avctx->bits_per_raw_sample == 20) {
117  const uint32_t *samples = (uint32_t *)frame->data[0];
118 
119  for (c = 0; c < frame->nb_samples; c++) {
120  uint8_t vucf = s->framing_index == 0 ? 0x80: 0;
121 
122  for (channels = 0; channels < avctx->channels; channels += 2) {
123  o[0] = ff_reverse[ (samples[0] & 0x000FF000) >> 12];
124  o[1] = ff_reverse[ (samples[0] & 0x0FF00000) >> 20];
125  o[2] = ff_reverse[((samples[0] & 0xF0000000) >> 28) | vucf];
126  o[3] = ff_reverse[ (samples[1] & 0x000FF000) >> 12];
127  o[4] = ff_reverse[ (samples[1] & 0x0FF00000) >> 20];
128  o[5] = ff_reverse[ (samples[1] & 0xF0000000) >> 28];
129  o += 6;
130  samples += 2;
131  }
132 
133  s->framing_index++;
134  if (s->framing_index >= 192)
135  s->framing_index = 0;
136  }
137  } else if (avctx->bits_per_raw_sample == 16) {
138  const uint16_t *samples = (uint16_t *)frame->data[0];
139 
140  for (c = 0; c < frame->nb_samples; c++) {
141  uint8_t vucf = s->framing_index == 0 ? 0x10 : 0;
142 
143  for (channels = 0; channels < avctx->channels; channels += 2) {
144  o[0] = ff_reverse[ samples[0] & 0xFF];
145  o[1] = ff_reverse[(samples[0] & 0xFF00) >> 8];
146  o[2] = ff_reverse[(samples[1] & 0x0F) << 4] | vucf;
147  o[3] = ff_reverse[(samples[1] & 0x0FF0) >> 4];
148  o[4] = ff_reverse[(samples[1] & 0xF000) >> 12];
149  o += 5;
150  samples += 2;
151 
152  }
153 
154  s->framing_index++;
155  if (s->framing_index >= 192)
156  s->framing_index = 0;
157  }
158  }
159 
160  *got_packet_ptr = 1;
161 
162  return 0;
163 }
164 
166  .name = "s302m",
167  .long_name = NULL_IF_CONFIG_SMALL("SMPTE 302M"),
168  .type = AVMEDIA_TYPE_AUDIO,
169  .id = AV_CODEC_ID_S302M,
170  .priv_data_size = sizeof(S302MEncContext),
172  .encode2 = s302m_encode2_frame,
173  .sample_fmts = (const enum AVSampleFormat[]){ AV_SAMPLE_FMT_S32,
177  .supported_samplerates = (const int[]) { 48000, 0 },
178 };