xref: /third_party/ffmpeg/libavcodec/s302menc.c (revision cabdff1a) 
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 "libavutil/channel_layout.h"
24#include "libavutil/reverse.h"
25#include "avcodec.h"
26#include "codec_internal.h"
27#include "encode.h"
28#include "mathops.h"
29#include "put_bits.h"
30
31#define AES3_HEADER_LEN 4
32
33typedef struct S302MEncContext {
34    uint8_t framing_index; /* Set for even channels on multiple of 192 samples */
35} S302MEncContext;
36
37static av_cold int s302m_encode_init(AVCodecContext *avctx)
38{
39    S302MEncContext *s = avctx->priv_data;
40
41    if (avctx->ch_layout.nb_channels & 1 || avctx->ch_layout.nb_channels > 8) {
42        av_log(avctx, AV_LOG_ERROR,
43               "Encoding %d channel(s) is not allowed. Only 2, 4, 6 and 8 channels are supported.\n",
44               avctx->ch_layout.nb_channels);
45        return AVERROR(EINVAL);
46    }
47
48    switch (avctx->sample_fmt) {
49    case AV_SAMPLE_FMT_S16:
50        avctx->bits_per_raw_sample = 16;
51        break;
52    case AV_SAMPLE_FMT_S32:
53        if (avctx->bits_per_raw_sample > 20) {
54            if (avctx->bits_per_raw_sample > 24)
55                av_log(avctx, AV_LOG_WARNING, "encoding as 24 bits-per-sample\n");
56            avctx->bits_per_raw_sample = 24;
57        } else if (!avctx->bits_per_raw_sample) {
58            avctx->bits_per_raw_sample = 24;
59        } else if (avctx->bits_per_raw_sample <= 20) {
60            avctx->bits_per_raw_sample = 20;
61        }
62    }
63
64    avctx->frame_size = 0;
65    avctx->bit_rate   = 48000 * avctx->ch_layout.nb_channels *
66                       (avctx->bits_per_raw_sample + 4);
67    s->framing_index  = 0;
68
69    return 0;
70}
71
72static int s302m_encode2_frame(AVCodecContext *avctx, AVPacket *avpkt,
73                               const AVFrame *frame, int *got_packet_ptr)
74{
75    S302MEncContext *s = avctx->priv_data;
76    const int nb_channels = avctx->ch_layout.nb_channels;
77    const int buf_size = AES3_HEADER_LEN +
78                        (frame->nb_samples * nb_channels *
79                        (avctx->bits_per_raw_sample + 4)) / 8;
80    int ret, c, channels;
81    uint8_t *o;
82    PutBitContext pb;
83
84    if (buf_size - AES3_HEADER_LEN > UINT16_MAX) {
85        av_log(avctx, AV_LOG_ERROR, "number of samples in frame too big\n");
86        return AVERROR(EINVAL);
87    }
88
89    if ((ret = ff_get_encode_buffer(avctx, avpkt, buf_size, 0)) < 0)
90        return ret;
91
92    o = avpkt->data;
93    init_put_bits(&pb, o, buf_size);
94    put_bits(&pb, 16, buf_size - AES3_HEADER_LEN);
95    put_bits(&pb, 2, (nb_channels - 2) >> 1);   // number of channels
96    put_bits(&pb, 8, 0);                            // channel ID
97    put_bits(&pb, 2, (avctx->bits_per_raw_sample - 16) / 4); // bits per samples (0 = 16bit, 1 = 20bit, 2 = 24bit)
98    put_bits(&pb, 4, 0);                            // alignments
99    flush_put_bits(&pb);
100    o += AES3_HEADER_LEN;
101
102    if (avctx->bits_per_raw_sample == 24) {
103        const uint32_t *samples = (uint32_t *)frame->data[0];
104
105        for (c = 0; c < frame->nb_samples; c++) {
106            uint8_t vucf = s->framing_index == 0 ? 0x10: 0;
107
108            for (channels = 0; channels < nb_channels; channels += 2) {
109                o[0] = ff_reverse[(samples[0] & 0x0000FF00) >> 8];
110                o[1] = ff_reverse[(samples[0] & 0x00FF0000) >> 16];
111                o[2] = ff_reverse[(samples[0] & 0xFF000000) >> 24];
112                o[3] = ff_reverse[(samples[1] & 0x00000F00) >> 4] | vucf;
113                o[4] = ff_reverse[(samples[1] & 0x000FF000) >> 12];
114                o[5] = ff_reverse[(samples[1] & 0x0FF00000) >> 20];
115                o[6] = ff_reverse[(samples[1] & 0xF0000000) >> 28];
116                o += 7;
117                samples += 2;
118            }
119
120            s->framing_index++;
121            if (s->framing_index >= 192)
122                s->framing_index = 0;
123        }
124    } else if (avctx->bits_per_raw_sample == 20) {
125        const uint32_t *samples = (uint32_t *)frame->data[0];
126
127        for (c = 0; c < frame->nb_samples; c++) {
128            uint8_t vucf = s->framing_index == 0 ? 0x80: 0;
129
130            for (channels = 0; channels < nb_channels; channels += 2) {
131                o[0] = ff_reverse[ (samples[0] & 0x000FF000) >> 12];
132                o[1] = ff_reverse[ (samples[0] & 0x0FF00000) >> 20];
133                o[2] = ff_reverse[((samples[0] & 0xF0000000) >> 28) | vucf];
134                o[3] = ff_reverse[ (samples[1] & 0x000FF000) >> 12];
135                o[4] = ff_reverse[ (samples[1] & 0x0FF00000) >> 20];
136                o[5] = ff_reverse[ (samples[1] & 0xF0000000) >> 28];
137                o += 6;
138                samples += 2;
139            }
140
141            s->framing_index++;
142            if (s->framing_index >= 192)
143                s->framing_index = 0;
144        }
145    } else if (avctx->bits_per_raw_sample == 16) {
146        const uint16_t *samples = (uint16_t *)frame->data[0];
147
148        for (c = 0; c < frame->nb_samples; c++) {
149            uint8_t vucf = s->framing_index == 0 ? 0x10 : 0;
150
151            for (channels = 0; channels < nb_channels; channels += 2) {
152                o[0] = ff_reverse[ samples[0] & 0xFF];
153                o[1] = ff_reverse[(samples[0] & 0xFF00) >>  8];
154                o[2] = ff_reverse[(samples[1] & 0x0F)   <<  4] | vucf;
155                o[3] = ff_reverse[(samples[1] & 0x0FF0) >>  4];
156                o[4] = ff_reverse[(samples[1] & 0xF000) >> 12];
157                o += 5;
158                samples += 2;
159
160            }
161
162            s->framing_index++;
163            if (s->framing_index >= 192)
164                s->framing_index = 0;
165        }
166    }
167
168    *got_packet_ptr = 1;
169
170    return 0;
171}
172
173const FFCodec ff_s302m_encoder = {
174    .p.name                = "s302m",
175    .p.long_name           = NULL_IF_CONFIG_SMALL("SMPTE 302M"),
176    .p.type                = AVMEDIA_TYPE_AUDIO,
177    .p.id                  = AV_CODEC_ID_S302M,
178    .p.capabilities        = AV_CODEC_CAP_DR1 | AV_CODEC_CAP_EXPERIMENTAL |
179                             AV_CODEC_CAP_VARIABLE_FRAME_SIZE,
180    .priv_data_size        = sizeof(S302MEncContext),
181    .init                  = s302m_encode_init,
182    FF_CODEC_ENCODE_CB(s302m_encode2_frame),
183    .p.sample_fmts         = (const enum AVSampleFormat[]){ AV_SAMPLE_FMT_S32,
184                                                            AV_SAMPLE_FMT_S16,
185                                                            AV_SAMPLE_FMT_NONE },
186    .p.supported_samplerates = (const int[]) { 48000, 0 },
187 /* .p.channel_layouts     = (const uint64_t[]) { AV_CH_LAYOUT_STEREO,
188                                                  AV_CH_LAYOUT_QUAD,
189                                                  AV_CH_LAYOUT_5POINT1_BACK,
190                                                  AV_CH_LAYOUT_5POINT1_BACK | AV_CH_LAYOUT_STEREO_DOWNMIX,
191                                                  0 }, */
192    .caps_internal         = FF_CODEC_CAP_INIT_THREADSAFE,
193};
194