1/*
2 * MPEG-2/4 AAC ADTS to MPEG-4 Audio Specific Configuration bitstream filter
3 * Copyright (c) 2009 Alex Converse <alex.converse@gmail.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 "adts_header.h"
23#include "adts_parser.h"
24#include "bsf.h"
25#include "bsf_internal.h"
26#include "put_bits.h"
27#include "get_bits.h"
28#include "mpeg4audio.h"
29
30typedef struct AACBSFContext {
31    int first_frame_done;
32} AACBSFContext;
33
34/**
35 * This filter creates an MPEG-4 AudioSpecificConfig from an MPEG-2/4
36 * ADTS header and removes the ADTS header.
37 */
38static int aac_adtstoasc_filter(AVBSFContext *bsfc, AVPacket *pkt)
39{
40    AACBSFContext *ctx = bsfc->priv_data;
41
42    GetBitContext gb;
43    PutBitContext pb;
44    AACADTSHeaderInfo hdr;
45    int ret;
46
47    ret = ff_bsf_get_packet_ref(bsfc, pkt);
48    if (ret < 0)
49        return ret;
50
51    if (bsfc->par_in->extradata && pkt->size >= 2 && (AV_RB16(pkt->data) >> 4) != 0xfff)
52        return 0;
53
54    if (pkt->size < AV_AAC_ADTS_HEADER_SIZE)
55        goto packet_too_small;
56
57    init_get_bits(&gb, pkt->data, AV_AAC_ADTS_HEADER_SIZE * 8);
58
59    if (ff_adts_header_parse(&gb, &hdr) < 0) {
60        av_log(bsfc, AV_LOG_ERROR, "Error parsing ADTS frame header!\n");
61        ret = AVERROR_INVALIDDATA;
62        goto fail;
63    }
64
65    if (!hdr.crc_absent && hdr.num_aac_frames > 1) {
66        avpriv_report_missing_feature(bsfc,
67                                      "Multiple RDBs per frame with CRC");
68        ret = AVERROR_PATCHWELCOME;
69        goto fail;
70    }
71
72    pkt->size -= AV_AAC_ADTS_HEADER_SIZE + 2 * !hdr.crc_absent;
73    if (pkt->size <= 0)
74        goto packet_too_small;
75    pkt->data += AV_AAC_ADTS_HEADER_SIZE + 2 * !hdr.crc_absent;
76
77    if (!ctx->first_frame_done) {
78        int            pce_size = 0;
79        uint8_t        pce_data[MAX_PCE_SIZE];
80        uint8_t       *extradata;
81
82        if (!hdr.chan_config) {
83            init_get_bits(&gb, pkt->data, pkt->size * 8);
84            if (get_bits(&gb, 3) != 5) {
85                avpriv_report_missing_feature(bsfc,
86                                              "PCE-based channel configuration "
87                                              "without PCE as first syntax "
88                                              "element");
89                ret = AVERROR_PATCHWELCOME;
90                goto fail;
91            }
92            init_put_bits(&pb, pce_data, MAX_PCE_SIZE);
93            pce_size = ff_copy_pce_data(&pb, &gb) / 8;
94            flush_put_bits(&pb);
95            pkt->size -= get_bits_count(&gb)/8;
96            pkt->data += get_bits_count(&gb)/8;
97        }
98
99        extradata = av_packet_new_side_data(pkt, AV_PKT_DATA_NEW_EXTRADATA,
100                                            2 + pce_size);
101        if (!extradata) {
102            ret = AVERROR(ENOMEM);
103            goto fail;
104        }
105
106        init_put_bits(&pb, extradata, 2 + pce_size);
107        put_bits(&pb, 5, hdr.object_type);
108        put_bits(&pb, 4, hdr.sampling_index);
109        put_bits(&pb, 4, hdr.chan_config);
110        put_bits(&pb, 1, 0); //frame length - 1024 samples
111        put_bits(&pb, 1, 0); //does not depend on core coder
112        put_bits(&pb, 1, 0); //is not extension
113        flush_put_bits(&pb);
114        if (pce_size) {
115            memcpy(extradata + 2, pce_data, pce_size);
116        }
117
118        ctx->first_frame_done = 1;
119    }
120
121    return 0;
122
123packet_too_small:
124    av_log(bsfc, AV_LOG_ERROR, "Input packet too small\n");
125    ret = AVERROR_INVALIDDATA;
126fail:
127    av_packet_unref(pkt);
128    return ret;
129}
130
131static int aac_adtstoasc_init(AVBSFContext *ctx)
132{
133    /* Validate the extradata if the stream is already MPEG-4 AudioSpecificConfig */
134    if (ctx->par_in->extradata) {
135        MPEG4AudioConfig mp4ac;
136        int ret = avpriv_mpeg4audio_get_config2(&mp4ac, ctx->par_in->extradata,
137                                                ctx->par_in->extradata_size, 1, ctx);
138        if (ret < 0) {
139            av_log(ctx, AV_LOG_ERROR, "Error parsing AudioSpecificConfig extradata!\n");
140            return ret;
141        }
142    }
143
144    return 0;
145}
146
147static const enum AVCodecID codec_ids[] = {
148    AV_CODEC_ID_AAC, AV_CODEC_ID_NONE,
149};
150
151const FFBitStreamFilter ff_aac_adtstoasc_bsf = {
152    .p.name         = "aac_adtstoasc",
153    .p.codec_ids    = codec_ids,
154    .priv_data_size = sizeof(AACBSFContext),
155    .init           = aac_adtstoasc_init,
156    .filter         = aac_adtstoasc_filter,
157};
158