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 */
32 } S302MEncContext;
33
s302m_encode_init(AVCodecContext * avctx)34 static av_cold int s302m_encode_init(AVCodecContext *avctx)
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
s302m_encode2_frame(AVCodecContext * avctx,AVPacket * avpkt,const AVFrame * frame,int * got_packet_ptr)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 * 8);
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
165 AVCodec ff_s302m_encoder = {
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),
171 .init = s302m_encode_init,
172 .encode2 = s302m_encode2_frame,
173 .sample_fmts = (const enum AVSampleFormat[]){ AV_SAMPLE_FMT_S32,
174 AV_SAMPLE_FMT_S16,
175 AV_SAMPLE_FMT_NONE },
176 .capabilities = CODEC_CAP_VARIABLE_FRAME_SIZE | CODEC_CAP_EXPERIMENTAL,
177 .supported_samplerates = (const int[]) { 48000, 0 },
178 };
179