1/*
2 * LATM/LOAS muxer
3 * Copyright (c) 2011 Kieran Kunhya <kieran@kunhya.com>
4 *
5 * This file is part of Libav.
6 *
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.
11 *
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.
16 *
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
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
29typedef struct {
30    AVClass *av_class;
31    int off;
32    int channel_conf;
33    int object_type;
34    int counter;
35    int mod;
36} LATMContext;
37
38static const AVOption options[] = {
39    {"smc-interval", "StreamMuxConfig interval.",
40     offsetof(LATMContext, mod), AV_OPT_TYPE_INT, {.dbl = 0x0014}, 0x0001, 0xffff, AV_OPT_FLAG_ENCODING_PARAM},
41    {NULL},
42};
43
44static const AVClass latm_muxer_class = {
45    .class_name = "LATM/LOAS muxer",
46    .item_name  = av_default_item_name,
47    .option     = options,
48    .version    = LIBAVUTIL_VERSION_INT,
49};
50
51static int latm_decode_extradata(LATMContext *ctx, uint8_t *buf, int size)
52{
53    GetBitContext gb;
54    MPEG4AudioConfig m4ac;
55
56    init_get_bits(&gb, buf, size * 8);
57    ctx->off = avpriv_mpeg4audio_get_config(&m4ac, buf, size * 8, 1);
58    if (ctx->off < 0)
59        return ctx->off;
60    skip_bits_long(&gb, ctx->off);
61
62    /* FIXME: are any formats not allowed in LATM? */
63
64    if (m4ac.object_type > AOT_SBR && m4ac.object_type != AOT_ALS) {
65        av_log(ctx, AV_LOG_ERROR, "Muxing MPEG-4 AOT %d in LATM is not supported\n", m4ac.object_type);
66        return AVERROR_INVALIDDATA;
67    }
68    ctx->channel_conf = m4ac.chan_config;
69    ctx->object_type  = m4ac.object_type;
70
71    return 0;
72}
73
74static int latm_write_header(AVFormatContext *s)
75{
76    LATMContext *ctx = s->priv_data;
77    AVCodecContext *avctx = s->streams[0]->codec;
78
79    if (avctx->extradata_size > 0 &&
80        latm_decode_extradata(ctx, avctx->extradata, avctx->extradata_size) < 0)
81        return AVERROR_INVALIDDATA;
82
83    return 0;
84}
85
86static int latm_write_frame_header(AVFormatContext *s, PutBitContext *bs)
87{
88    LATMContext *ctx = s->priv_data;
89    AVCodecContext *avctx = s->streams[0]->codec;
90    GetBitContext gb;
91    int header_size;
92
93    /* AudioMuxElement */
94    put_bits(bs, 1, !!ctx->counter);
95
96    if (!ctx->counter) {
97        init_get_bits(&gb, avctx->extradata, avctx->extradata_size * 8);
98
99        /* StreamMuxConfig */
100        put_bits(bs, 1, 0); /* audioMuxVersion */
101        put_bits(bs, 1, 1); /* allStreamsSameTimeFraming */
102        put_bits(bs, 6, 0); /* numSubFrames */
103        put_bits(bs, 4, 0); /* numProgram */
104        put_bits(bs, 3, 0); /* numLayer */
105
106        /* AudioSpecificConfig */
107        if (ctx->object_type == AOT_ALS) {
108            header_size = avctx->extradata_size-(ctx->off + 7) >> 3;
109            avpriv_copy_bits(bs, &avctx->extradata[ctx->off], header_size);
110        } else {
111            avpriv_copy_bits(bs, avctx->extradata, ctx->off + 3);
112
113            if (!ctx->channel_conf) {
114                avpriv_copy_pce_data(bs, &gb);
115            }
116        }
117
118        put_bits(bs, 3, 0); /* frameLengthType */
119        put_bits(bs, 8, 0xff); /* latmBufferFullness */
120
121        put_bits(bs, 1, 0); /* otherDataPresent */
122        put_bits(bs, 1, 0); /* crcCheckPresent */
123    }
124
125    ctx->counter++;
126    ctx->counter %= ctx->mod;
127
128    return 0;
129}
130
131static int latm_write_packet(AVFormatContext *s, AVPacket *pkt)
132{
133    AVIOContext *pb = s->pb;
134    PutBitContext bs;
135    int i, len;
136    uint8_t loas_header[] = "\x56\xe0\x00";
137    uint8_t *buf;
138
139    if (pkt->size > 2 && pkt->data[0] == 0xff && (pkt->data[1] >> 4) == 0xf) {
140        av_log(s, AV_LOG_ERROR, "ADTS header detected - ADTS will not be incorrectly muxed into LATM\n");
141        return AVERROR_INVALIDDATA;
142    }
143
144    buf = av_malloc(pkt->size+1024);
145    if (!buf)
146        return AVERROR(ENOMEM);
147
148    init_put_bits(&bs, buf, pkt->size+1024);
149
150    latm_write_frame_header(s, &bs);
151
152    /* PayloadLengthInfo() */
153    for (i = 0; i <= pkt->size-255; i+=255)
154        put_bits(&bs, 8, 255);
155
156    put_bits(&bs, 8, pkt->size-i);
157
158    /* The LATM payload is written unaligned */
159
160    /* PayloadMux() */
161    for (i = 0; i < pkt->size; i++)
162        put_bits(&bs, 8, pkt->data[i]);
163
164    avpriv_align_put_bits(&bs);
165    flush_put_bits(&bs);
166
167    len = put_bits_count(&bs) >> 3;
168
169    loas_header[1] |= (len >> 8) & 0x1f;
170    loas_header[2] |= len & 0xff;
171
172    avio_write(pb, loas_header, 3);
173    avio_write(pb, buf, len);
174
175    av_free(buf);
176
177    return 0;
178}
179
180AVOutputFormat ff_latm_muxer = {
181    .name           = "latm",
182    .long_name      = NULL_IF_CONFIG_SMALL("LOAS/LATM"),
183    .mime_type      = "audio/MP4A-LATM",
184    .extensions     = "latm",
185    .priv_data_size = sizeof(LATMContext),
186    .audio_codec    = CODEC_ID_AAC,
187    .video_codec    = CODEC_ID_NONE,
188    .write_header   = latm_write_header,
189    .write_packet   = latm_write_packet,
190    .priv_class     = &latm_muxer_class,
191};
192