1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
|
/*
* LATM/LOAS muxer
* Copyright (c) 2011 Kieran Kunhya <kieran@kunhya.com>
*
* This file is part of Libav.
*
* Libav is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* Libav is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with Libav; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/
#include "libavcodec/get_bits.h"
#include "libavcodec/put_bits.h"
#include "libavcodec/avcodec.h"
#include "libavcodec/mpeg4audio.h"
#include "libavutil/opt.h"
#include "avformat.h"
typedef struct {
AVClass *av_class;
int off;
int channel_conf;
int object_type;
int counter;
int mod;
} LATMContext;
static const AVOption options[] = {
{"smc-interval", "StreamMuxConfig interval.",
offsetof(LATMContext, mod), AV_OPT_TYPE_INT, {.dbl = 0x0014}, 0x0001, 0xffff, AV_OPT_FLAG_ENCODING_PARAM},
{NULL},
};
static const AVClass latm_muxer_class = {
.class_name = "LATM/LOAS muxer",
.item_name = av_default_item_name,
.option = options,
.version = LIBAVUTIL_VERSION_INT,
};
static int latm_decode_extradata(LATMContext *ctx, uint8_t *buf, int size)
{
GetBitContext gb;
MPEG4AudioConfig m4ac;
init_get_bits(&gb, buf, size * 8);
ctx->off = avpriv_mpeg4audio_get_config(&m4ac, buf, size);
if (ctx->off < 0)
return ctx->off;
skip_bits_long(&gb, ctx->off);
/* FIXME: are any formats not allowed in LATM? */
if (m4ac.object_type > AOT_SBR && m4ac.object_type != AOT_ALS) {
av_log(ctx, AV_LOG_ERROR, "Muxing MPEG-4 AOT %d in LATM is not supported\n", m4ac.object_type);
return AVERROR_INVALIDDATA;
}
ctx->channel_conf = m4ac.chan_config;
ctx->object_type = m4ac.object_type;
return 0;
}
static int latm_write_header(AVFormatContext *s)
{
LATMContext *ctx = s->priv_data;
AVCodecContext *avctx = s->streams[0]->codec;
if (avctx->extradata_size > 0 &&
latm_decode_extradata(ctx, avctx->extradata, avctx->extradata_size) < 0)
return AVERROR_INVALIDDATA;
return 0;
}
static int latm_write_frame_header(AVFormatContext *s, PutBitContext *bs)
{
LATMContext *ctx = s->priv_data;
AVCodecContext *avctx = s->streams[0]->codec;
GetBitContext gb;
int header_size;
/* AudioMuxElement */
put_bits(bs, 1, !!ctx->counter);
if (!ctx->counter) {
init_get_bits(&gb, avctx->extradata, avctx->extradata_size * 8);
/* StreamMuxConfig */
put_bits(bs, 1, 0); /* audioMuxVersion */
put_bits(bs, 1, 1); /* allStreamsSameTimeFraming */
put_bits(bs, 6, 0); /* numSubFrames */
put_bits(bs, 4, 0); /* numProgram */
put_bits(bs, 3, 0); /* numLayer */
/* AudioSpecificConfig */
if (ctx->object_type == AOT_ALS) {
header_size = avctx->extradata_size-(ctx->off + 7) >> 3;
ff_copy_bits(bs, &avctx->extradata[ctx->off], header_size);
} else {
ff_copy_bits(bs, avctx->extradata, ctx->off + 3);
if (!ctx->channel_conf) {
avpriv_copy_pce_data(bs, &gb);
}
}
put_bits(bs, 3, 0); /* frameLengthType */
put_bits(bs, 8, 0xff); /* latmBufferFullness */
put_bits(bs, 1, 0); /* otherDataPresent */
put_bits(bs, 1, 0); /* crcCheckPresent */
}
ctx->counter++;
ctx->counter %= ctx->mod;
return 0;
}
static int latm_write_packet(AVFormatContext *s, AVPacket *pkt)
{
AVIOContext *pb = s->pb;
PutBitContext bs;
int i, len;
uint8_t loas_header[] = "\x56\xe0\x00";
uint8_t *buf;
if (pkt->size > 2 && pkt->data[0] == 0xff && (pkt->data[1] >> 4) == 0xf) {
av_log(s, AV_LOG_ERROR, "ADTS header detected - ADTS will not be incorrectly muxed into LATM\n");
return AVERROR_INVALIDDATA;
}
buf = av_malloc(pkt->size+1024);
if (!buf)
return AVERROR(ENOMEM);
init_put_bits(&bs, buf, pkt->size+1024);
latm_write_frame_header(s, &bs);
/* PayloadLengthInfo() */
for (i = 0; i <= pkt->size-255; i+=255)
put_bits(&bs, 8, 255);
put_bits(&bs, 8, pkt->size-i);
/* The LATM payload is written unaligned */
/* PayloadMux() */
for (i = 0; i < pkt->size; i++)
put_bits(&bs, 8, pkt->data[i]);
align_put_bits(&bs);
flush_put_bits(&bs);
len = put_bits_count(&bs) >> 3;
loas_header[1] |= (len >> 8) & 0x1f;
loas_header[2] |= len & 0xff;
avio_write(pb, loas_header, 3);
avio_write(pb, buf, len);
av_free(buf);
return 0;
}
AVOutputFormat ff_latm_muxer = {
.name = "latm",
.long_name = NULL_IF_CONFIG_SMALL("LOAS/LATM"),
.mime_type = "audio/MP4A-LATM",
.extensions = "latm",
.priv_data_size = sizeof(LATMContext),
.audio_codec = CODEC_ID_AAC,
.video_codec = CODEC_ID_NONE,
.write_header = latm_write_header,
.write_packet = latm_write_packet,
.priv_class = &latm_muxer_class,
};
|
