1/*
2 * ADTS muxer.
3 * Copyright (c) 2006 Baptiste Coudurier <baptiste.coudurier@smartjog.com>
4 *                    Mans Rullgard <mans@mansr.com>
5 *
6 * This file is part of FFmpeg.
7 *
8 * FFmpeg is free software; you can redistribute it and/or
9 * modify it under the terms of the GNU Lesser General Public
10 * License as published by the Free Software Foundation; either
11 * version 2.1 of the License, or (at your option) any later version.
12 *
13 * FFmpeg is distributed in the hope that it will be useful,
14 * but WITHOUT ANY WARRANTY; without even the implied warranty of
15 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
16 * Lesser General Public License for more details.
17 *
18 * You should have received a copy of the GNU Lesser General Public
19 * License along with FFmpeg; if not, write to the Free Software
20 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
21 */
22
23#include "libavcodec/bitstream.h"
24#include "libavcodec/internal.h"
25#include "avformat.h"
26
27#define ADTS_HEADER_SIZE 7
28
29typedef struct {
30    int write_adts;
31    int objecttype;
32    int sample_rate_index;
33    int channel_conf;
34} ADTSContext;
35
36static int decode_extradata(AVFormatContext *s, ADTSContext *adts, uint8_t *buf, int size)
37{
38    GetBitContext gb;
39
40    init_get_bits(&gb, buf, size * 8);
41    adts->objecttype = get_bits(&gb, 5) - 1;
42    adts->sample_rate_index = get_bits(&gb, 4);
43    adts->channel_conf = get_bits(&gb, 4);
44
45    if (adts->objecttype > 3) {
46        av_log(s, AV_LOG_ERROR, "MPEG-4 AOT %d is not allowed in ADTS\n", adts->objecttype+1);
47        return -1;
48    }
49    if (adts->sample_rate_index == 15) {
50        av_log(s, AV_LOG_ERROR, "Escape sample rate index illegal in ADTS\n");
51        return -1;
52    }
53    if (adts->channel_conf == 0) {
54        ff_log_missing_feature(s, "PCE based channel configuration", 0);
55        return -1;
56    }
57
58    adts->write_adts = 1;
59
60    return 0;
61}
62
63static int adts_write_header(AVFormatContext *s)
64{
65    ADTSContext *adts = s->priv_data;
66    AVCodecContext *avc = s->streams[0]->codec;
67
68    if(avc->extradata_size > 0 &&
69            decode_extradata(s, adts, avc->extradata, avc->extradata_size) < 0)
70        return -1;
71
72    return 0;
73}
74
75static int adts_write_frame_header(AVFormatContext *s, int size)
76{
77    ADTSContext *ctx = s->priv_data;
78    PutBitContext pb;
79    uint8_t buf[ADTS_HEADER_SIZE];
80
81    init_put_bits(&pb, buf, ADTS_HEADER_SIZE);
82
83    /* adts_fixed_header */
84    put_bits(&pb, 12, 0xfff);   /* syncword */
85    put_bits(&pb, 1, 0);        /* ID */
86    put_bits(&pb, 2, 0);        /* layer */
87    put_bits(&pb, 1, 1);        /* protection_absent */
88    put_bits(&pb, 2, ctx->objecttype); /* profile_objecttype */
89    put_bits(&pb, 4, ctx->sample_rate_index);
90    put_bits(&pb, 1, 0);        /* private_bit */
91    put_bits(&pb, 3, ctx->channel_conf); /* channel_configuration */
92    put_bits(&pb, 1, 0);        /* original_copy */
93    put_bits(&pb, 1, 0);        /* home */
94
95    /* adts_variable_header */
96    put_bits(&pb, 1, 0);        /* copyright_identification_bit */
97    put_bits(&pb, 1, 0);        /* copyright_identification_start */
98    put_bits(&pb, 13, ADTS_HEADER_SIZE + size); /* aac_frame_length */
99    put_bits(&pb, 11, 0x7ff);   /* adts_buffer_fullness */
100    put_bits(&pb, 2, 0);        /* number_of_raw_data_blocks_in_frame */
101
102    flush_put_bits(&pb);
103    put_buffer(s->pb, buf, ADTS_HEADER_SIZE);
104
105    return 0;
106}
107
108static int adts_write_packet(AVFormatContext *s, AVPacket *pkt)
109{
110    ADTSContext *adts = s->priv_data;
111    ByteIOContext *pb = s->pb;
112
113    if (!pkt->size)
114        return 0;
115    if(adts->write_adts)
116        adts_write_frame_header(s, pkt->size);
117    put_buffer(pb, pkt->data, pkt->size);
118    put_flush_packet(pb);
119
120    return 0;
121}
122
123AVOutputFormat adts_muxer = {
124    "adts",
125    NULL_IF_CONFIG_SMALL("ADTS AAC"),
126    "audio/aac",
127    "aac",
128    sizeof(ADTSContext),
129    CODEC_ID_AAC,
130    CODEC_ID_NONE,
131    adts_write_header,
132    adts_write_packet,
133};
134