3 * Copyright (c) 2011 Kieran Kunhya <kieran@kunhya.com>
5 * This file is part of Libav.
7 * Libav 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.
12 * Libav 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.
17 * You should have received a copy of the GNU Lesser General Public
18 * License along with Libav; if not, write to the Free Software
19 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
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"
30 #define MAX_EXTRADATA_SIZE 1024
39 uint8_t buffer[0x1fff + MAX_EXTRADATA_SIZE + 1024];
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},
48 static const AVClass latm_muxer_class = {
49 .class_name = "LATM/LOAS muxer",
50 .item_name = av_default_item_name,
52 .version = LIBAVUTIL_VERSION_INT,
55 static int latm_decode_extradata(LATMContext *ctx, uint8_t *buf, int size)
57 MPEG4AudioConfig m4ac;
59 if (size > MAX_EXTRADATA_SIZE) {
60 av_log(ctx, AV_LOG_ERROR, "Extradata is larger than currently supported.\n");
61 return AVERROR_INVALIDDATA;
63 ctx->off = avpriv_mpeg4audio_get_config(&m4ac, buf, size * 8, 1);
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;
72 /* FIXME: are any formats not allowed in LATM? */
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;
78 ctx->channel_conf = m4ac.chan_config;
79 ctx->object_type = m4ac.object_type;
84 static int latm_write_header(AVFormatContext *s)
86 LATMContext *ctx = s->priv_data;
87 AVCodecContext *avctx = s->streams[0]->codec;
89 if (avctx->codec_id == AV_CODEC_ID_AAC_LATM)
92 if (avctx->extradata_size > 0 &&
93 latm_decode_extradata(ctx, avctx->extradata, avctx->extradata_size) < 0)
94 return AVERROR_INVALIDDATA;
99 static void latm_write_frame_header(AVFormatContext *s, PutBitContext *bs)
101 LATMContext *ctx = s->priv_data;
102 AVCodecContext *avctx = s->streams[0]->codec;
105 /* AudioMuxElement */
106 put_bits(bs, 1, !!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 */
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);
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);
125 if (!ctx->channel_conf) {
127 init_get_bits(&gb, avctx->extradata, avctx->extradata_size * 8);
128 skip_bits_long(&gb, ctx->off + 3);
129 avpriv_copy_pce_data(bs, &gb);
133 put_bits(bs, 3, 0); /* frameLengthType */
134 put_bits(bs, 8, 0xff); /* latmBufferFullness */
136 put_bits(bs, 1, 0); /* otherDataPresent */
137 put_bits(bs, 1, 0); /* crcCheckPresent */
141 ctx->counter %= ctx->mod;
144 static int latm_write_packet(AVFormatContext *s, AVPacket *pkt)
146 LATMContext *ctx = s->priv_data;
147 AVIOContext *pb = s->pb;
150 uint8_t loas_header[] = "\x56\xe0\x00";
152 if (s->streams[0]->codec->codec_id == AV_CODEC_ID_AAC_LATM)
153 return ff_raw_write_packet(s, pkt);
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;
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);
165 return AVERROR_INVALIDDATA;
168 if (pkt->size > 0x1fff)
171 init_put_bits(&bs, ctx->buffer, pkt->size+1024+MAX_EXTRADATA_SIZE);
173 latm_write_frame_header(s, &bs);
175 /* PayloadLengthInfo() */
176 for (i = 0; i <= pkt->size-255; i+=255)
177 put_bits(&bs, 8, 255);
179 put_bits(&bs, 8, pkt->size-i);
181 /* The LATM payload is written unaligned */
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);
196 avpriv_copy_bits(&bs, pkt->data, 8*pkt->size);
198 avpriv_align_put_bits(&bs);
201 len = put_bits_count(&bs) >> 3;
206 loas_header[1] |= (len >> 8) & 0x1f;
207 loas_header[2] |= len & 0xff;
209 avio_write(pb, loas_header, 3);
210 avio_write(pb, ctx->buffer, len);
215 av_log(s, AV_LOG_ERROR, "LATM packet size larger than maximum size 0x1fff\n");
216 return AVERROR_INVALIDDATA;
219 AVOutputFormat ff_latm_muxer = {
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,