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