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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 "put_bits.h"
26 
27 #define AES3_HEADER_LEN 4
28 
29 typedef struct S302MEncContext {
30  uint8_t framing_index; /* Set for even channels on multiple of 192 samples */
32 
34 {
35  S302MEncContext *s = avctx->priv_data;
36 
37  if (avctx->channels & 1 || avctx->channels > 8) {
38  av_log(avctx, AV_LOG_ERROR,
39  "Encoding %d channel(s) is not allowed. Only 2, 4, 6 and 8 channels are supported.\n",
40  avctx->channels);
41  return AVERROR(EINVAL);
42  }
43 
44  switch (avctx->sample_fmt) {
45  case AV_SAMPLE_FMT_S16:
46  avctx->bits_per_raw_sample = 16;
47  break;
48  case AV_SAMPLE_FMT_S32:
49  if (avctx->bits_per_raw_sample > 20) {
50  if (avctx->bits_per_raw_sample > 24)
51  av_log(avctx, AV_LOG_WARNING, "encoding as 24 bits-per-sample\n");
52  avctx->bits_per_raw_sample = 24;
53  } else if (!avctx->bits_per_raw_sample) {
54  avctx->bits_per_raw_sample = 24;
55  } else if (avctx->bits_per_raw_sample <= 20) {
56  avctx->bits_per_raw_sample = 20;
57  }
58  }
59 
60  avctx->frame_size = 0;
61  avctx->bit_rate = 48000 * avctx->channels *
62  (avctx->bits_per_raw_sample + 4);
63  s->framing_index = 0;
64 
65  return 0;
66 }
67 
68 static int s302m_encode2_frame(AVCodecContext *avctx, AVPacket *avpkt,
69  const AVFrame *frame, int *got_packet_ptr)
70 {
71  S302MEncContext *s = avctx->priv_data;
72  const int buf_size = AES3_HEADER_LEN +
73  (frame->nb_samples *
74  avctx->channels *
75  (avctx->bits_per_raw_sample + 4)) / 8;
76  int ret, c, channels;
77  uint8_t *o;
78  PutBitContext pb;
79 
80  if ((ret = ff_alloc_packet2(avctx, avpkt, buf_size)) < 0)
81  return ret;
82 
83  o = avpkt->data;
84  init_put_bits(&pb, o, buf_size * 8);
85  put_bits(&pb, 16, buf_size - AES3_HEADER_LEN);
86  put_bits(&pb, 2, (avctx->channels - 2) >> 1); // number of channels
87  put_bits(&pb, 8, 0); // channel ID
88  put_bits(&pb, 2, (avctx->bits_per_raw_sample - 16) / 4); // bits per samples (0 = 16bit, 1 = 20bit, 2 = 24bit)
89  put_bits(&pb, 4, 0); // alignments
90  flush_put_bits(&pb);
91  o += AES3_HEADER_LEN;
92 
93  if (avctx->bits_per_raw_sample == 24) {
94  const uint32_t *samples = (uint32_t *)frame->data[0];
95 
96  for (c = 0; c < frame->nb_samples; c++) {
97  uint8_t vucf = s->framing_index == 0 ? 0x10: 0;
98 
99  for (channels = 0; channels < avctx->channels; channels += 2) {
100  o[0] = ff_reverse[(samples[0] & 0x0000FF00) >> 8];
101  o[1] = ff_reverse[(samples[0] & 0x00FF0000) >> 16];
102  o[2] = ff_reverse[(samples[0] & 0xFF000000) >> 24];
103  o[3] = ff_reverse[(samples[1] & 0x00000F00) >> 4] | vucf;
104  o[4] = ff_reverse[(samples[1] & 0x000FF000) >> 12];
105  o[5] = ff_reverse[(samples[1] & 0x0FF00000) >> 20];
106  o[6] = ff_reverse[(samples[1] & 0xF0000000) >> 28];
107  o += 7;
108  samples += 2;
109  }
110 
111  s->framing_index++;
112  if (s->framing_index >= 192)
113  s->framing_index = 0;
114  }
115  } else if (avctx->bits_per_raw_sample == 20) {
116  const uint32_t *samples = (uint32_t *)frame->data[0];
117 
118  for (c = 0; c < frame->nb_samples; c++) {
119  uint8_t vucf = s->framing_index == 0 ? 0x80: 0;
120 
121  for (channels = 0; channels < avctx->channels; channels += 2) {
122  o[0] = ff_reverse[ (samples[0] & 0x000FF000) >> 12];
123  o[1] = ff_reverse[ (samples[0] & 0x0FF00000) >> 20];
124  o[2] = ff_reverse[((samples[0] & 0xF0000000) >> 28) | vucf];
125  o[3] = ff_reverse[ (samples[1] & 0x000FF000) >> 12];
126  o[4] = ff_reverse[ (samples[1] & 0x0FF00000) >> 20];
127  o[5] = ff_reverse[ (samples[1] & 0xF0000000) >> 28];
128  o += 6;
129  samples += 2;
130  }
131 
132  s->framing_index++;
133  if (s->framing_index >= 192)
134  s->framing_index = 0;
135  }
136  } else if (avctx->bits_per_raw_sample == 16) {
137  const uint16_t *samples = (uint16_t *)frame->data[0];
138 
139  for (c = 0; c < frame->nb_samples; c++) {
140  uint8_t vucf = s->framing_index == 0 ? 0x10 : 0;
141 
142  for (channels = 0; channels < avctx->channels; channels += 2) {
143  o[0] = ff_reverse[ samples[0] & 0xFF];
144  o[1] = ff_reverse[(samples[0] & 0xFF00) >> 8];
145  o[2] = ff_reverse[(samples[1] & 0x0F) << 4] | vucf;
146  o[3] = ff_reverse[(samples[1] & 0x0FF0) >> 4];
147  o[4] = ff_reverse[(samples[1] & 0xF000) >> 12];
148  o += 5;
149  samples += 2;
150 
151  }
152 
153  s->framing_index++;
154  if (s->framing_index >= 192)
155  s->framing_index = 0;
156  }
157  }
158 
159  *got_packet_ptr = 1;
160 
161  return 0;
162 }
163 
165  .name = "s302m",
166  .long_name = NULL_IF_CONFIG_SMALL("SMPTE 302M"),
167  .type = AVMEDIA_TYPE_AUDIO,
168  .id = AV_CODEC_ID_S302M,
169  .priv_data_size = sizeof(S302MEncContext),
171  .encode2 = s302m_encode2_frame,
172  .sample_fmts = (const enum AVSampleFormat[]){ AV_SAMPLE_FMT_S32,
176  .supported_samplerates = (const int[]) { 48000, 0 },
177 };