FFmpeg coverage

Directory: ../../../ffmpeg/
File: src/libavformat/latmenc.c
Date: 2026-04-24 10:13:59
Exec Total Coverage
Lines: 78 111 70.3%
Functions: 6 6 100.0%
Branches: 28 68 41.2%
Line Branch Exec Source
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 "libavcodec/mpeg4audio_copy_pce.h"
29 #include "libavutil/opt.h"
30 #include "avformat.h"
31 #include "internal.h"
32 #include "mux.h"
33 #include "rawenc.h"
34
35 #define MAX_EXTRADATA_SIZE 1024
36
37 typedef struct LATMContext {
38 AVClass *av_class;
39 int off;
40 int channel_conf;
41 int object_type;
42 int counter;
43 int mod;
44 uint8_t buffer[0x1fff + MAX_EXTRADATA_SIZE + 1024];
45 } LATMContext;
46
47 static const AVOption options[] = {
48 {"smc-interval", "StreamMuxConfig interval.",
49 offsetof(LATMContext, mod), AV_OPT_TYPE_INT, {.i64 = 0x0014}, 0x0001, 0xffff, AV_OPT_FLAG_ENCODING_PARAM},
50 {NULL},
51 };
52
53 static const AVClass latm_muxer_class = {
54 .class_name = "LATM/LOAS muxer",
55 .item_name = av_default_item_name,
56 .option = options,
57 .version = LIBAVUTIL_VERSION_INT,
58 };
59
60 1 static int latm_decode_extradata(AVFormatContext *s, uint8_t *buf, int size)
61 {
62 1 LATMContext *ctx = s->priv_data;
63 MPEG4AudioConfig m4ac;
64
65
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 1 if (size > MAX_EXTRADATA_SIZE) {
66 ✗ av_log(s, AV_LOG_ERROR, "Extradata is larger than currently supported.\n");
67 ✗ return AVERROR_INVALIDDATA;
68 }
69 1 ctx->off = avpriv_mpeg4audio_get_config2(&m4ac, buf, size, 1, s);
70
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 1 if (ctx->off < 0)
71 ✗ return ctx->off;
72
73
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 1 if (ctx->object_type == AOT_ALS && (ctx->off & 7)) {
74 // as long as avpriv_mpeg4audio_get_config works correctly this is impossible
75 ✗ av_log(s, AV_LOG_ERROR, "BUG: ALS offset is not byte-aligned\n");
76 ✗ return AVERROR_INVALIDDATA;
77 }
78 /* FIXME: are any formats not allowed in LATM? */
79
80
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 1 if (m4ac.object_type > AOT_SBR && m4ac.object_type != AOT_ALS) {
81 ✗ av_log(s, AV_LOG_ERROR, "Muxing MPEG-4 AOT %d in LATM is not supported\n", m4ac.object_type);
82 ✗ return AVERROR_INVALIDDATA;
83 }
84 1 ctx->channel_conf = m4ac.chan_config;
85 1 ctx->object_type = m4ac.object_type;
86
87 1 return 0;
88 }
89
90 1 static int latm_write_header(AVFormatContext *s)
91 {
92 1 AVCodecParameters *par = s->streams[0]->codecpar;
93
94
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 1 if (par->codec_id == AV_CODEC_ID_AAC_LATM)
95 ✗ return 0;
96
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 1 if (par->codec_id != AV_CODEC_ID_AAC && par->codec_id != AV_CODEC_ID_MP4ALS) {
97 ✗ av_log(s, AV_LOG_ERROR, "Only AAC, LATM and ALS are supported\n");
98 ✗ return AVERROR(EINVAL);
99 }
100
101
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 2 if (par->extradata_size > 0 &&
102 1 latm_decode_extradata(s, par->extradata, par->extradata_size) < 0)
103 ✗ return AVERROR_INVALIDDATA;
104
105 1 return 0;
106 }
107
108 373 static void copy_bits(PutBitContext *pb, const uint8_t *src, int length)
109 {
110 373 int words = length >> 4;
111 373 int bits = length & 15;
112 int i;
113
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 33071 for (i = 0; i < words; i++)
114 32698 put_bits(pb, 16, AV_RB16(src + 2 * i));
115
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 373 if (bits)
116 164 put_bits(pb, bits, AV_RB16(src + 2 * words) >> (16 - bits));
117 373 }
118
119 355 static void latm_write_frame_header(AVFormatContext *s, PutBitContext *bs)
120 {
121 355 LATMContext *ctx = s->priv_data;
122 355 AVCodecParameters *par = s->streams[0]->codecpar;
123 int header_size;
124
125 /* AudioMuxElement */
126 355 put_bits(bs, 1, !!ctx->counter);
127
128
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 355 if (!ctx->counter) {
129 /* StreamMuxConfig */
130 18 put_bits(bs, 1, 0); /* audioMuxVersion */
131 18 put_bits(bs, 1, 1); /* allStreamsSameTimeFraming */
132 18 put_bits(bs, 6, 0); /* numSubFrames */
133 18 put_bits(bs, 4, 0); /* numProgram */
134 18 put_bits(bs, 3, 0); /* numLayer */
135
136 /* AudioSpecificConfig */
137
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 18 if (ctx->object_type == AOT_ALS) {
138 ✗ header_size = (par->extradata_size - (ctx->off >> 3)) * 8;
139 ✗ copy_bits(bs, &par->extradata[ctx->off >> 3], header_size);
140 } else {
141 // + 3 assumes not scalable and dependsOnCoreCoder == 0,
142 // see decode_ga_specific_config in libavcodec/aacdec.c
143 18 copy_bits(bs, par->extradata, ctx->off + 3);
144
145
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 18 if (!ctx->channel_conf) {
146 GetBitContext gb;
147 18 int ret = init_get_bits8(&gb, par->extradata, par->extradata_size);
148
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 18 av_assert0(ret >= 0); // extradata size has been checked already, so this should not fail
149 18 skip_bits_long(&gb, ctx->off + 3);
150 18 ff_copy_pce_data(bs, &gb);
151 }
152 }
153
154 18 put_bits(bs, 3, 0); /* frameLengthType */
155 18 put_bits(bs, 8, 0xff); /* latmBufferFullness */
156
157 18 put_bits(bs, 1, 0); /* otherDataPresent */
158 18 put_bits(bs, 1, 0); /* crcCheckPresent */
159 }
160
161 355 ctx->counter++;
162 355 ctx->counter %= ctx->mod;
163 355 }
164
165 355 static int latm_write_packet(AVFormatContext *s, AVPacket *pkt)
166 {
167 355 LATMContext *ctx = s->priv_data;
168 355 AVCodecParameters *par = s->streams[0]->codecpar;
169 355 AVIOContext *pb = s->pb;
170 PutBitContext bs;
171 int i, len;
172 355 uint8_t loas_header[] = "\x56\xe0\x00";
173
174
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 355 if (par->codec_id == AV_CODEC_ID_AAC_LATM)
175 ✗ return ff_raw_write_packet(s, pkt);
176
177
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 355 if (!par->extradata) {
178 ✗ if(pkt->size > 2 && pkt->data[0] == 0x56 && (pkt->data[1] >> 4) == 0xe &&
179 ✗ (AV_RB16(pkt->data + 1) & 0x1FFF) + 3 == pkt->size)
180 ✗ return ff_raw_write_packet(s, pkt);
181 else {
182 uint8_t *side_data;
183 size_t side_data_size;
184 int ret;
185
186 ✗ side_data = av_packet_get_side_data(pkt, AV_PKT_DATA_NEW_EXTRADATA,
187 &side_data_size);
188 ✗ if (side_data_size) {
189 ✗ if (latm_decode_extradata(s, side_data, side_data_size) < 0)
190 ✗ return AVERROR_INVALIDDATA;
191 ✗ ret = ff_alloc_extradata(par, side_data_size);
192 ✗ if (ret < 0)
193 ✗ return ret;
194 ✗ memcpy(par->extradata, side_data, side_data_size);
195 } else
196 ✗ return AVERROR_INVALIDDATA;
197 }
198 }
199
200
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 355 if (pkt->size > 0x1fff)
201 ✗ goto too_large;
202
203 355 init_put_bits(&bs, ctx->buffer, pkt->size+1024+MAX_EXTRADATA_SIZE);
204
205 355 latm_write_frame_header(s, &bs);
206
207 /* PayloadLengthInfo() */
208
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 361 for (i = 0; i <= pkt->size-255; i+=255)
209 6 put_bits(&bs, 8, 255);
210
211 355 put_bits(&bs, 8, pkt->size-i);
212
213 /* The LATM payload is written unaligned */
214
215 /* PayloadMux() */
216
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 355 if (pkt->size && (pkt->data[0] & 0xe1) == 0x81) {
217 // Convert byte-aligned DSE to non-aligned.
218 // Due to the input format encoding we know that
219 // it is naturally byte-aligned in the input stream,
220 // so there are no padding bits to account for.
221 // To avoid having to add padding bits and rearrange
222 // the whole stream we just remove the byte-align flag.
223 // This allows us to remux our FATE AAC samples into latm
224 // files that are still playable with minimal effort.
225 355 put_bits(&bs, 8, pkt->data[0] & 0xfe);
226 355 copy_bits(&bs, pkt->data + 1, 8*pkt->size - 8);
227 } else
228 ✗ copy_bits(&bs, pkt->data, 8*pkt->size);
229
230 355 flush_put_bits(&bs);
231
232 355 len = put_bytes_output(&bs);
233
234
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 355 if (len > 0x1fff)
235 ✗ goto too_large;
236
237 355 loas_header[1] |= (len >> 8) & 0x1f;
238 355 loas_header[2] |= len & 0xff;
239
240 355 avio_write(pb, loas_header, 3);
241 355 avio_write(pb, ctx->buffer, len);
242
243 355 return 0;
244
245 ✗ too_large:
246 ✗ av_log(s, AV_LOG_ERROR, "LATM packet size larger than maximum size 0x1fff\n");
247 ✗ return AVERROR_INVALIDDATA;
248 }
249
250 1 static int latm_check_bitstream(AVFormatContext *s, AVStream *st,
251 const AVPacket *pkt)
252 {
253 1 int ret = 1;
254
255
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 1 if (st->codecpar->codec_id == AV_CODEC_ID_AAC) {
256
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 1 if (pkt->size > 2 && (AV_RB16(pkt->data) & 0xfff0) == 0xfff0)
257 ✗ ret = ff_stream_add_bitstream_filter(st, "aac_adtstoasc", NULL);
258 }
259
260 1 return ret;
261 }
262
263 const FFOutputFormat ff_latm_muxer = {
264 .p.name = "latm",
265 .p.long_name = NULL_IF_CONFIG_SMALL("LOAS/LATM"),
266 .p.mime_type = "audio/MP4A-LATM",
267 .p.extensions = "latm,loas",
268 .priv_data_size = sizeof(LATMContext),
269 .p.audio_codec = AV_CODEC_ID_AAC,
270 .p.video_codec = AV_CODEC_ID_NONE,
271 .p.subtitle_codec = AV_CODEC_ID_NONE,
272 .flags_internal = FF_OFMT_FLAG_MAX_ONE_OF_EACH,
273 .write_header = latm_write_header,
274 .write_packet = latm_write_packet,
275 .p.priv_class = &latm_muxer_class,
276 .check_bitstream= latm_check_bitstream,
277 .p.flags = AVFMT_NOTIMESTAMPS,
278 };
279