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/codec_id.h"
25 #include "libavcodec/codec_par.h"
26 #include "libavcodec/packet.h"
27 #include "libavcodec/mpeg4audio.h"
28 #include "libavutil/opt.h"
29 #include "avformat.h"
30 #include "internal.h"
31 #include "mux.h"
32 #include "rawenc.h"
33
34 #define MAX_EXTRADATA_SIZE 1024
35
36 typedef struct LATMContext {
37 AVClass *av_class;
38 int off;
39 int channel_conf;
40 int object_type;
41 int counter;
42 int mod;
43 uint8_t buffer[0x1fff + MAX_EXTRADATA_SIZE + 1024];
44 } LATMContext;
45
46 static const AVOption options[] = {
47 {"smc-interval", "StreamMuxConfig interval.",
48 offsetof(LATMContext, mod), AV_OPT_TYPE_INT, {.i64 = 0x0014}, 0x0001, 0xffff, AV_OPT_FLAG_ENCODING_PARAM},
49 {NULL},
50 };
51
52 static const AVClass latm_muxer_class = {
53 .class_name = "LATM/LOAS muxer",
54 .item_name = av_default_item_name,
55 .option = options,
56 .version = LIBAVUTIL_VERSION_INT,
57 };
58
latm_decode_extradata(AVFormatContext * s,uint8_t * buf,int size)59 static int latm_decode_extradata(AVFormatContext *s, uint8_t *buf, int size)
60 {
61 LATMContext *ctx = s->priv_data;
62 MPEG4AudioConfig m4ac;
63
64 if (size > MAX_EXTRADATA_SIZE) {
65 av_log(s, AV_LOG_ERROR, "Extradata is larger than currently supported.\n");
66 return AVERROR_INVALIDDATA;
67 }
68 ctx->off = avpriv_mpeg4audio_get_config2(&m4ac, buf, size, 1, s);
69 if (ctx->off < 0)
70 return ctx->off;
71
72 if (ctx->object_type == AOT_ALS && (ctx->off & 7)) {
73 // as long as avpriv_mpeg4audio_get_config works correctly this is impossible
74 av_log(s, AV_LOG_ERROR, "BUG: ALS offset is not byte-aligned\n");
75 return AVERROR_INVALIDDATA;
76 }
77 /* FIXME: are any formats not allowed in LATM? */
78
79 if (m4ac.object_type > AOT_SBR && m4ac.object_type != AOT_ALS) {
80 av_log(s, AV_LOG_ERROR, "Muxing MPEG-4 AOT %d in LATM is not supported\n", m4ac.object_type);
81 return AVERROR_INVALIDDATA;
82 }
83 ctx->channel_conf = m4ac.chan_config;
84 ctx->object_type = m4ac.object_type;
85
86 return 0;
87 }
88
latm_write_header(AVFormatContext * s)89 static int latm_write_header(AVFormatContext *s)
90 {
91 AVCodecParameters *par = s->streams[0]->codecpar;
92
93 if (par->codec_id == AV_CODEC_ID_AAC_LATM)
94 return 0;
95 if (par->codec_id != AV_CODEC_ID_AAC && par->codec_id != AV_CODEC_ID_MP4ALS) {
96 av_log(s, AV_LOG_ERROR, "Only AAC, LATM and ALS are supported\n");
97 return AVERROR(EINVAL);
98 }
99
100 if (par->extradata_size > 0 &&
101 latm_decode_extradata(s, par->extradata, par->extradata_size) < 0)
102 return AVERROR_INVALIDDATA;
103
104 return 0;
105 }
106
copy_bits(PutBitContext * pb,const uint8_t * src,int length)107 static void copy_bits(PutBitContext *pb, const uint8_t *src, int length)
108 {
109 int words = length >> 4;
110 int bits = length & 15;
111 int i;
112 for (i = 0; i < words; i++)
113 put_bits(pb, 16, AV_RB16(src + 2 * i));
114 if (bits)
115 put_bits(pb, bits, AV_RB16(src + 2 * words) >> (16 - bits));
116 }
117
latm_write_frame_header(AVFormatContext * s,PutBitContext * bs)118 static void latm_write_frame_header(AVFormatContext *s, PutBitContext *bs)
119 {
120 LATMContext *ctx = s->priv_data;
121 AVCodecParameters *par = s->streams[0]->codecpar;
122 int header_size;
123
124 /* AudioMuxElement */
125 put_bits(bs, 1, !!ctx->counter);
126
127 if (!ctx->counter) {
128 /* StreamMuxConfig */
129 put_bits(bs, 1, 0); /* audioMuxVersion */
130 put_bits(bs, 1, 1); /* allStreamsSameTimeFraming */
131 put_bits(bs, 6, 0); /* numSubFrames */
132 put_bits(bs, 4, 0); /* numProgram */
133 put_bits(bs, 3, 0); /* numLayer */
134
135 /* AudioSpecificConfig */
136 if (ctx->object_type == AOT_ALS) {
137 header_size = (par->extradata_size - (ctx->off >> 3)) * 8;
138 copy_bits(bs, &par->extradata[ctx->off >> 3], header_size);
139 } else {
140 // + 3 assumes not scalable and dependsOnCoreCoder == 0,
141 // see decode_ga_specific_config in libavcodec/aacdec.c
142 copy_bits(bs, par->extradata, ctx->off + 3);
143
144 if (!ctx->channel_conf) {
145 GetBitContext gb;
146 int ret = init_get_bits8(&gb, par->extradata, par->extradata_size);
147 av_assert0(ret >= 0); // extradata size has been checked already, so this should not fail
148 skip_bits_long(&gb, ctx->off + 3);
149 ff_copy_pce_data(bs, &gb);
150 }
151 }
152
153 put_bits(bs, 3, 0); /* frameLengthType */
154 put_bits(bs, 8, 0xff); /* latmBufferFullness */
155
156 put_bits(bs, 1, 0); /* otherDataPresent */
157 put_bits(bs, 1, 0); /* crcCheckPresent */
158 }
159
160 ctx->counter++;
161 ctx->counter %= ctx->mod;
162 }
163
latm_write_packet(AVFormatContext * s,AVPacket * pkt)164 static int latm_write_packet(AVFormatContext *s, AVPacket *pkt)
165 {
166 LATMContext *ctx = s->priv_data;
167 AVCodecParameters *par = s->streams[0]->codecpar;
168 AVIOContext *pb = s->pb;
169 PutBitContext bs;
170 int i, len;
171 uint8_t loas_header[] = "\x56\xe0\x00";
172
173 if (par->codec_id == AV_CODEC_ID_AAC_LATM)
174 return ff_raw_write_packet(s, pkt);
175
176 if (!par->extradata) {
177 if(pkt->size > 2 && pkt->data[0] == 0x56 && (pkt->data[1] >> 4) == 0xe &&
178 (AV_RB16(pkt->data + 1) & 0x1FFF) + 3 == pkt->size)
179 return ff_raw_write_packet(s, pkt);
180 else {
181 uint8_t *side_data;
182 size_t side_data_size;
183 int ret;
184
185 side_data = av_packet_get_side_data(pkt, AV_PKT_DATA_NEW_EXTRADATA,
186 &side_data_size);
187 if (side_data_size) {
188 if (latm_decode_extradata(s, side_data, side_data_size) < 0)
189 return AVERROR_INVALIDDATA;
190 ret = ff_alloc_extradata(par, side_data_size);
191 if (ret < 0)
192 return ret;
193 memcpy(par->extradata, side_data, side_data_size);
194 } else
195 return AVERROR_INVALIDDATA;
196 }
197 }
198
199 if (pkt->size > 0x1fff)
200 goto too_large;
201
202 init_put_bits(&bs, ctx->buffer, pkt->size+1024+MAX_EXTRADATA_SIZE);
203
204 latm_write_frame_header(s, &bs);
205
206 /* PayloadLengthInfo() */
207 for (i = 0; i <= pkt->size-255; i+=255)
208 put_bits(&bs, 8, 255);
209
210 put_bits(&bs, 8, pkt->size-i);
211
212 /* The LATM payload is written unaligned */
213
214 /* PayloadMux() */
215 if (pkt->size && (pkt->data[0] & 0xe1) == 0x81) {
216 // Convert byte-aligned DSE to non-aligned.
217 // Due to the input format encoding we know that
218 // it is naturally byte-aligned in the input stream,
219 // so there are no padding bits to account for.
220 // To avoid having to add padding bits and rearrange
221 // the whole stream we just remove the byte-align flag.
222 // This allows us to remux our FATE AAC samples into latm
223 // files that are still playable with minimal effort.
224 put_bits(&bs, 8, pkt->data[0] & 0xfe);
225 copy_bits(&bs, pkt->data + 1, 8*pkt->size - 8);
226 } else
227 copy_bits(&bs, pkt->data, 8*pkt->size);
228
229 flush_put_bits(&bs);
230
231 len = put_bytes_output(&bs);
232
233 if (len > 0x1fff)
234 goto too_large;
235
236 loas_header[1] |= (len >> 8) & 0x1f;
237 loas_header[2] |= len & 0xff;
238
239 avio_write(pb, loas_header, 3);
240 avio_write(pb, ctx->buffer, len);
241
242 return 0;
243
244 too_large:
245 av_log(s, AV_LOG_ERROR, "LATM packet size larger than maximum size 0x1fff\n");
246 return AVERROR_INVALIDDATA;
247 }
248
latm_check_bitstream(AVFormatContext * s,AVStream * st,const AVPacket * pkt)249 static int latm_check_bitstream(AVFormatContext *s, AVStream *st,
250 const AVPacket *pkt)
251 {
252 int ret = 1;
253
254 if (st->codecpar->codec_id == AV_CODEC_ID_AAC) {
255 if (pkt->size > 2 && (AV_RB16(pkt->data) & 0xfff0) == 0xfff0)
256 ret = ff_stream_add_bitstream_filter(st, "aac_adtstoasc", NULL);
257 }
258
259 return ret;
260 }
261
262 const AVOutputFormat ff_latm_muxer = {
263 .name = "latm",
264 .long_name = NULL_IF_CONFIG_SMALL("LOAS/LATM"),
265 .mime_type = "audio/MP4A-LATM",
266 .extensions = "latm,loas",
267 .priv_data_size = sizeof(LATMContext),
268 .audio_codec = AV_CODEC_ID_AAC,
269 .video_codec = AV_CODEC_ID_NONE,
270 .write_header = latm_write_header,
271 .write_packet = latm_write_packet,
272 .priv_class = &latm_muxer_class,
273 .check_bitstream= latm_check_bitstream,
274 .flags = AVFMT_NOTIMESTAMPS,
275 };
276