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
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
|
/*
* 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"
#include "rawenc.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)
{
MPEG4AudioConfig m4ac;
ctx->off = avpriv_mpeg4audio_get_config(&m4ac, buf, size * 8, 1);
if (ctx->off < 0)
return ctx->off;
if (ctx->object_type == AOT_ALS && (ctx->off & 7)) {
// as long as avpriv_mpeg4audio_get_config works correctly this is impossible
av_log(ctx, AV_LOG_ERROR, "BUG: ALS offset is not byte-aligned\n");
return AVERROR_INVALIDDATA;
}
/* 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->codec_id == CODEC_ID_AAC_LATM)
return 0;
if (avctx->extradata_size > 0 &&
latm_decode_extradata(ctx, avctx->extradata, avctx->extradata_size) < 0)
return AVERROR_INVALIDDATA;
return 0;
}
static void 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 >> 3);
avpriv_copy_bits(bs, &avctx->extradata[ctx->off >> 3], header_size);
} else {
avpriv_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;
}
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 = NULL;
if (s->streams[0]->codec->codec_id == CODEC_ID_AAC_LATM)
return ff_raw_write_packet(s, pkt);
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;
}
if (pkt->size > 0x1fff)
goto too_large;
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 */
i = 0;
if (pkt->size && (pkt->data[0] & 0xe1) == 0x81) {
// Convert byte-aligned DSE to non-aligned.
// Due to the input format encoding we know that
// it is naturally byte-aligned in the input stream,
// so there are no padding bits to account for.
// To avoid having to add padding bits and rearrange
// the whole stream we just remove the byte-align flag.
// This allows us to remux our FATE AAC samples into latm
// files that are still playable with minimal effort.
put_bits(&bs, 8, pkt->data[0] & 0xfe);
i++;
}
/* PayloadMux() */
for (; i < pkt->size; i++)
put_bits(&bs, 8, pkt->data[i]);
avpriv_align_put_bits(&bs);
flush_put_bits(&bs);
len = put_bits_count(&bs) >> 3;
if (len > 0x1fff)
goto too_large;
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;
too_large:
av_log(s, AV_LOG_ERROR, "LATM packet size larger than maximum size 0x1fff\n");
av_free(buf);
return AVERROR_INVALIDDATA;
}
AVOutputFormat ff_latm_muxer = {
.name = "latm",
.long_name = NULL_IF_CONFIG_SMALL("LOAS/LATM"),
.mime_type = "audio/MP4A-LATM",
.extensions = "latm,loas",
.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,
};
|
