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 Libav.
7 *
8 * Libav 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 * Libav 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 Libav; 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/get_bits.h"
24#include "libavcodec/put_bits.h"
25#include "libavcodec/avcodec.h"
26#include "libavcodec/mpeg4audio.h"
27#include "avformat.h"
28#include "adts.h"
29
30#define ADTS_MAX_FRAME_BYTES ((1 << 13) - 1)
31
32int ff_adts_decode_extradata(AVFormatContext *s, ADTSContext *adts, uint8_t *buf, int size)
33{
34    GetBitContext gb;
35    PutBitContext pb;
36    MPEG4AudioConfig m4ac;
37    int off;
38
39    init_get_bits(&gb, buf, size * 8);
40    off = avpriv_mpeg4audio_get_config(&m4ac, buf, size * 8, 1);
41    if (off < 0)
42        return off;
43    skip_bits_long(&gb, off);
44    adts->objecttype        = m4ac.object_type - 1;
45    adts->sample_rate_index = m4ac.sampling_index;
46    adts->channel_conf      = m4ac.chan_config;
47
48    if (adts->objecttype > 3U) {
49        av_log(s, AV_LOG_ERROR, "MPEG-4 AOT %d is not allowed in ADTS\n", adts->objecttype+1);
50        return -1;
51    }
52    if (adts->sample_rate_index == 15) {
53        av_log(s, AV_LOG_ERROR, "Escape sample rate index illegal in ADTS\n");
54        return -1;
55    }
56    if (get_bits(&gb, 1)) {
57        av_log(s, AV_LOG_ERROR, "960/120 MDCT window is not allowed in ADTS\n");
58        return -1;
59    }
60    if (get_bits(&gb, 1)) {
61        av_log(s, AV_LOG_ERROR, "Scalable configurations are not allowed in ADTS\n");
62        return -1;
63    }
64    if (get_bits(&gb, 1)) {
65        av_log(s, AV_LOG_ERROR, "Extension flag is not allowed in ADTS\n");
66        return -1;
67    }
68    if (!adts->channel_conf) {
69        init_put_bits(&pb, adts->pce_data, MAX_PCE_SIZE);
70
71        put_bits(&pb, 3, 5); //ID_PCE
72        adts->pce_size = (avpriv_copy_pce_data(&pb, &gb) + 3) / 8;
73        flush_put_bits(&pb);
74    }
75
76    adts->write_adts = 1;
77
78    return 0;
79}
80
81static int adts_write_header(AVFormatContext *s)
82{
83    ADTSContext *adts = s->priv_data;
84    AVCodecContext *avc = s->streams[0]->codec;
85
86    if (avc->extradata_size > 0 &&
87            ff_adts_decode_extradata(s, adts, avc->extradata, avc->extradata_size) < 0)
88        return -1;
89
90    return 0;
91}
92
93int ff_adts_write_frame_header(ADTSContext *ctx,
94                               uint8_t *buf, int size, int pce_size)
95{
96    PutBitContext pb;
97
98    unsigned full_frame_size = (unsigned)ADTS_HEADER_SIZE + size + pce_size;
99    if (full_frame_size > ADTS_MAX_FRAME_BYTES) {
100        av_log(NULL, AV_LOG_ERROR, "ADTS frame size too large: %u (max %d)\n",
101               full_frame_size, ADTS_MAX_FRAME_BYTES);
102        return AVERROR_INVALIDDATA;
103    }
104
105    init_put_bits(&pb, buf, ADTS_HEADER_SIZE);
106
107    /* adts_fixed_header */
108    put_bits(&pb, 12, 0xfff);   /* syncword */
109    put_bits(&pb, 1, 0);        /* ID */
110    put_bits(&pb, 2, 0);        /* layer */
111    put_bits(&pb, 1, 1);        /* protection_absent */
112    put_bits(&pb, 2, ctx->objecttype); /* profile_objecttype */
113    put_bits(&pb, 4, ctx->sample_rate_index);
114    put_bits(&pb, 1, 0);        /* private_bit */
115    put_bits(&pb, 3, ctx->channel_conf); /* channel_configuration */
116    put_bits(&pb, 1, 0);        /* original_copy */
117    put_bits(&pb, 1, 0);        /* home */
118
119    /* adts_variable_header */
120    put_bits(&pb, 1, 0);        /* copyright_identification_bit */
121    put_bits(&pb, 1, 0);        /* copyright_identification_start */
122    put_bits(&pb, 13, full_frame_size); /* aac_frame_length */
123    put_bits(&pb, 11, 0x7ff);   /* adts_buffer_fullness */
124    put_bits(&pb, 2, 0);        /* number_of_raw_data_blocks_in_frame */
125
126    flush_put_bits(&pb);
127
128    return 0;
129}
130
131static int adts_write_packet(AVFormatContext *s, AVPacket *pkt)
132{
133    ADTSContext *adts = s->priv_data;
134    AVIOContext *pb = s->pb;
135    uint8_t buf[ADTS_HEADER_SIZE];
136
137    if (!pkt->size)
138        return 0;
139    if (adts->write_adts) {
140        int err = ff_adts_write_frame_header(adts, buf, pkt->size,
141                                             adts->pce_size);
142        if (err < 0)
143            return err;
144        avio_write(pb, buf, ADTS_HEADER_SIZE);
145        if (adts->pce_size) {
146            avio_write(pb, adts->pce_data, adts->pce_size);
147            adts->pce_size = 0;
148        }
149    }
150    avio_write(pb, pkt->data, pkt->size);
151    avio_flush(pb);
152
153    return 0;
154}
155
156AVOutputFormat ff_adts_muxer = {
157    .name              = "adts",
158    .long_name         = NULL_IF_CONFIG_SMALL("ADTS AAC"),
159    .mime_type         = "audio/aac",
160    .extensions        = "aac,adts",
161    .priv_data_size    = sizeof(ADTSContext),
162    .audio_codec       = CODEC_ID_AAC,
163    .video_codec       = CODEC_ID_NONE,
164    .write_header      = adts_write_header,
165    .write_packet      = adts_write_packet,
166};
167