1 /*
2 * LATM/LOAS muxer
3 * Copyright (c) 2011 Kieran Kunhya <kieran@kunhya.com>
4 *
5 * This file is part of FFmpeg.
6 *
7 * FFmpeg is free software; you can redistribute it and/or
8 * modify it under the terms of the GNU Lesser General Public
9 * License as published by the Free Software Foundation; either
10 * version 2.1 of the License, or (at your option) any later version.
11 *
12 * FFmpeg is distributed in the hope that it will be useful,
13 * but WITHOUT ANY WARRANTY; without even the implied warranty of
14 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
15 * Lesser General Public License for more details.
16 *
17 * You should have received a copy of the GNU Lesser General Public
18 * License along with FFmpeg; if not, write to the Free Software
19 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
20 */
21
22 #include "libavcodec/get_bits.h"
23 #include "libavcodec/put_bits.h"
24 #include "libavcodec/avcodec.h"
25 #include "libavcodec/mpeg4audio.h"
26 #include "libavutil/opt.h"
27 #include "avformat.h"
28 #include "internal.h"
29 #include "rawenc.h"
30
31 #define MAX_EXTRADATA_SIZE 1024
32
33 typedef struct LATMContext {
34 AVClass *av_class;
35 int off;
36 int channel_conf;
37 int object_type;
38 int counter;
39 int mod;
40 uint8_t buffer[0x1fff + MAX_EXTRADATA_SIZE + 1024];
41 } LATMContext;
42
43 static const AVOption options[] = {
44 {"smc-interval", "StreamMuxConfig interval.",
45 offsetof(LATMContext, mod), AV_OPT_TYPE_INT, {.i64 = 0x0014}, 0x0001, 0xffff, AV_OPT_FLAG_ENCODING_PARAM},
46 {NULL},
47 };
48
49 static const AVClass latm_muxer_class = {
50 .class_name = "LATM/LOAS muxer",
51 .item_name = av_default_item_name,
52 .option = options,
53 .version = LIBAVUTIL_VERSION_INT,
54 };
55
latm_decode_extradata(AVFormatContext * s,uint8_t * buf,int size)56 static int latm_decode_extradata(AVFormatContext *s, uint8_t *buf, int size)
57 {
58 LATMContext *ctx = s->priv_data;
59 MPEG4AudioConfig m4ac;
60
61 if (size > MAX_EXTRADATA_SIZE) {
62 av_log(s, AV_LOG_ERROR, "Extradata is larger than currently supported.\n");
63 return AVERROR_INVALIDDATA;
64 }
65 ctx->off = avpriv_mpeg4audio_get_config2(&m4ac, buf, size, 1, s);
66 if (ctx->off < 0)
67 return ctx->off;
68
69 if (ctx->object_type == AOT_ALS && (ctx->off & 7)) {
70 // as long as avpriv_mpeg4audio_get_config works correctly this is impossible
71 av_log(s, AV_LOG_ERROR, "BUG: ALS offset is not byte-aligned\n");
72 return AVERROR_INVALIDDATA;
73 }
74 /* FIXME: are any formats not allowed in LATM? */
75
76 if (m4ac.object_type > AOT_SBR && m4ac.object_type != AOT_ALS) {
77 av_log(s, AV_LOG_ERROR, "Muxing MPEG-4 AOT %d in LATM is not supported\n", m4ac.object_type);
78 return AVERROR_INVALIDDATA;
79 }
80 ctx->channel_conf = m4ac.chan_config;
81 ctx->object_type = m4ac.object_type;
82
83 return 0;
84 }
85
latm_write_header(AVFormatContext * s)86 static int latm_write_header(AVFormatContext *s)
87 {
88 AVCodecParameters *par = s->streams[0]->codecpar;
89
90 if (par->codec_id == AV_CODEC_ID_AAC_LATM)
91 return 0;
92 if (par->codec_id != AV_CODEC_ID_AAC && par->codec_id != AV_CODEC_ID_MP4ALS) {
93 av_log(s, AV_LOG_ERROR, "Only AAC, LATM and ALS are supported\n");
94 return AVERROR(EINVAL);
95 }
96
97 if (par->extradata_size > 0 &&
98 latm_decode_extradata(s, par->extradata, par->extradata_size) < 0)
99 return AVERROR_INVALIDDATA;
100
101 return 0;
102 }
103
copy_bits(PutBitContext * pb,const uint8_t * src,int length)104 static void copy_bits(PutBitContext *pb, const uint8_t *src, int length)
105 {
106 int words = length >> 4;
107 int bits = length & 15;
108 int i;
109 for (i = 0; i < words; i++)
110 put_bits(pb, 16, AV_RB16(src + 2 * i));
111 if (bits)
112 put_bits(pb, bits, AV_RB16(src + 2 * words) >> (16 - bits));
113 }
114
latm_write_frame_header(AVFormatContext * s,PutBitContext * bs)115 static void latm_write_frame_header(AVFormatContext *s, PutBitContext *bs)
116 {
117 LATMContext *ctx = s->priv_data;
118 AVCodecParameters *par = s->streams[0]->codecpar;
119 int header_size;
120
121 /* AudioMuxElement */
122 put_bits(bs, 1, !!ctx->counter);
123
124 if (!ctx->counter) {
125 /* StreamMuxConfig */
126 put_bits(bs, 1, 0); /* audioMuxVersion */
127 put_bits(bs, 1, 1); /* allStreamsSameTimeFraming */
128 put_bits(bs, 6, 0); /* numSubFrames */
129 put_bits(bs, 4, 0); /* numProgram */
130 put_bits(bs, 3, 0); /* numLayer */
131
132 /* AudioSpecificConfig */
133 if (ctx->object_type == AOT_ALS) {
134 header_size = (par->extradata_size - (ctx->off >> 3)) * 8;
135 copy_bits(bs, &par->extradata[ctx->off >> 3], header_size);
136 } else {
137 // + 3 assumes not scalable and dependsOnCoreCoder == 0,
138 // see decode_ga_specific_config in libavcodec/aacdec.c
139 copy_bits(bs, par->extradata, ctx->off + 3);
140
141 if (!ctx->channel_conf) {
142 GetBitContext gb;
143 int ret = init_get_bits8(&gb, par->extradata, par->extradata_size);
144 av_assert0(ret >= 0); // extradata size has been checked already, so this should not fail
145 skip_bits_long(&gb, ctx->off + 3);
146 ff_copy_pce_data(bs, &gb);
147 }
148 }
149
150 put_bits(bs, 3, 0); /* frameLengthType */
151 put_bits(bs, 8, 0xff); /* latmBufferFullness */
152
153 put_bits(bs, 1, 0); /* otherDataPresent */
154 put_bits(bs, 1, 0); /* crcCheckPresent */
155 }
156
157 ctx->counter++;
158 ctx->counter %= ctx->mod;
159 }
160
latm_write_packet(AVFormatContext * s,AVPacket * pkt)161 static int latm_write_packet(AVFormatContext *s, AVPacket *pkt)
162 {
163 LATMContext *ctx = s->priv_data;
164 AVCodecParameters *par = s->streams[0]->codecpar;
165 AVIOContext *pb = s->pb;
166 PutBitContext bs;
167 int i, len;
168 uint8_t loas_header[] = "\x56\xe0\x00";
169
170 if (par->codec_id == AV_CODEC_ID_AAC_LATM)
171 return ff_raw_write_packet(s, pkt);
172
173 if (!par->extradata) {
174 if(pkt->size > 2 && pkt->data[0] == 0x56 && (pkt->data[1] >> 4) == 0xe &&
175 (AV_RB16(pkt->data + 1) & 0x1FFF) + 3 == pkt->size)
176 return ff_raw_write_packet(s, pkt);
177 else {
178 uint8_t *side_data;
179 buffer_size_t side_data_size;
180 int ret;
181
182 side_data = av_packet_get_side_data(pkt, AV_PKT_DATA_NEW_EXTRADATA,
183 &side_data_size);
184 if (side_data_size) {
185 if (latm_decode_extradata(s, side_data, side_data_size) < 0)
186 return AVERROR_INVALIDDATA;
187 ret = ff_alloc_extradata(par, side_data_size);
188 if (ret < 0)
189 return ret;
190 memcpy(par->extradata, side_data, side_data_size);
191 } else
192 return AVERROR_INVALIDDATA;
193 }
194 }
195
196 if (pkt->size > 0x1fff)
197 goto too_large;
198
199 init_put_bits(&bs, ctx->buffer, pkt->size+1024+MAX_EXTRADATA_SIZE);
200
201 latm_write_frame_header(s, &bs);
202
203 /* PayloadLengthInfo() */
204 for (i = 0; i <= pkt->size-255; i+=255)
205 put_bits(&bs, 8, 255);
206
207 put_bits(&bs, 8, pkt->size-i);
208
209 /* The LATM payload is written unaligned */
210
211 /* PayloadMux() */
212 if (pkt->size && (pkt->data[0] & 0xe1) == 0x81) {
213 // Convert byte-aligned DSE to non-aligned.
214 // Due to the input format encoding we know that
215 // it is naturally byte-aligned in the input stream,
216 // so there are no padding bits to account for.
217 // To avoid having to add padding bits and rearrange
218 // the whole stream we just remove the byte-align flag.
219 // This allows us to remux our FATE AAC samples into latm
220 // files that are still playable with minimal effort.
221 put_bits(&bs, 8, pkt->data[0] & 0xfe);
222 copy_bits(&bs, pkt->data + 1, 8*pkt->size - 8);
223 } else
224 copy_bits(&bs, pkt->data, 8*pkt->size);
225
226 flush_put_bits(&bs);
227
228 len = put_bits_count(&bs) >> 3;
229
230 if (len > 0x1fff)
231 goto too_large;
232
233 loas_header[1] |= (len >> 8) & 0x1f;
234 loas_header[2] |= len & 0xff;
235
236 avio_write(pb, loas_header, 3);
237 avio_write(pb, ctx->buffer, len);
238
239 return 0;
240
241 too_large:
242 av_log(s, AV_LOG_ERROR, "LATM packet size larger than maximum size 0x1fff\n");
243 return AVERROR_INVALIDDATA;
244 }
245
latm_check_bitstream(struct AVFormatContext * s,const AVPacket * pkt)246 static int latm_check_bitstream(struct AVFormatContext *s, const AVPacket *pkt)
247 {
248 int ret = 1;
249 AVStream *st = s->streams[pkt->stream_index];
250
251 if (st->codecpar->codec_id == AV_CODEC_ID_AAC) {
252 if (pkt->size > 2 && (AV_RB16(pkt->data) & 0xfff0) == 0xfff0)
253 ret = ff_stream_add_bitstream_filter(st, "aac_adtstoasc", NULL);
254 }
255
256 return ret;
257 }
258
259 AVOutputFormat ff_latm_muxer = {
260 .name = "latm",
261 .long_name = NULL_IF_CONFIG_SMALL("LOAS/LATM"),
262 .mime_type = "audio/MP4A-LATM",
263 .extensions = "latm,loas",
264 .priv_data_size = sizeof(LATMContext),
265 .audio_codec = AV_CODEC_ID_AAC,
266 .video_codec = AV_CODEC_ID_NONE,
267 .write_header = latm_write_header,
268 .write_packet = latm_write_packet,
269 .priv_class = &latm_muxer_class,
270 .check_bitstream= latm_check_bitstream,
271 .flags = AVFMT_NOTIMESTAMPS,
272 };
273