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 "avcodec.h"
23#include "aac_parser.h"
24#include "put_bits.h"
25#include "get_bits.h"
26#include "mpeg4audio.h"
27#include "internal.h"
28
29typedef struct AACBSFContext {
30    int first_frame_done;
31} AACBSFContext;
32
33/**
34 * This filter creates an MPEG-4 AudioSpecificConfig from an MPEG-2/4
35 * ADTS header and removes the ADTS header.
36 */
37static int aac_adtstoasc_filter(AVBitStreamFilterContext *bsfc,
38                                AVCodecContext *avctx, const char *args,
39                                uint8_t  **poutbuf, int *poutbuf_size,
40                                const uint8_t *buf, int      buf_size,
41                                int keyframe)
42{
43    GetBitContext gb;
44    PutBitContext pb;
45    AACADTSHeaderInfo hdr;
46
47    AACBSFContext *ctx = bsfc->priv_data;
48
49    init_get_bits(&gb, buf, AAC_ADTS_HEADER_SIZE*8);
50
51    *poutbuf = (uint8_t*) buf;
52    *poutbuf_size = buf_size;
53
54    if (avctx->extradata)
55        if (show_bits(&gb, 12) != 0xfff)
56            return 0;
57
58    if (ff_aac_parse_header(&gb, &hdr) < 0) {
59        av_log(avctx, AV_LOG_ERROR, "Error parsing ADTS frame header!\n");
60        return -1;
61    }
62
63    if (!hdr.crc_absent && hdr.num_aac_frames > 1) {
64        av_log_missing_feature(avctx, "Multiple RDBs per frame with CRC is", 0);
65        return -1;
66    }
67
68    buf      += AAC_ADTS_HEADER_SIZE + 2*!hdr.crc_absent;
69    buf_size -= AAC_ADTS_HEADER_SIZE + 2*!hdr.crc_absent;
70
71    if (!ctx->first_frame_done) {
72        int            pce_size = 0;
73        uint8_t        pce_data[MAX_PCE_SIZE];
74        if (!hdr.chan_config) {
75            init_get_bits(&gb, buf, buf_size);
76            if (get_bits(&gb, 3) != 5) {
77                av_log_missing_feature(avctx, "PCE based channel configuration, where the PCE is not the first syntax element is", 0);
78                return -1;
79            }
80            init_put_bits(&pb, pce_data, MAX_PCE_SIZE);
81            pce_size = ff_copy_pce_data(&pb, &gb)/8;
82            flush_put_bits(&pb);
83            buf_size -= get_bits_count(&gb)/8;
84            buf      += get_bits_count(&gb)/8;
85        }
86        avctx->extradata_size = 2 + pce_size;
87        avctx->extradata = av_mallocz(avctx->extradata_size + FF_INPUT_BUFFER_PADDING_SIZE);
88
89        init_put_bits(&pb, avctx->extradata, avctx->extradata_size);
90        put_bits(&pb, 5, hdr.object_type);
91        put_bits(&pb, 4, hdr.sampling_index);
92        put_bits(&pb, 4, hdr.chan_config);
93        put_bits(&pb, 1, 0); //frame length - 1024 samples
94        put_bits(&pb, 1, 0); //does not depend on core coder
95        put_bits(&pb, 1, 0); //is not extension
96        flush_put_bits(&pb);
97        if (pce_size) {
98            memcpy(avctx->extradata + 2, pce_data, pce_size);
99        }
100
101        ctx->first_frame_done = 1;
102    }
103
104    *poutbuf = (uint8_t*) buf;
105    *poutbuf_size = buf_size;
106
107    return 0;
108}
109
110AVBitStreamFilter aac_adtstoasc_bsf = {
111    "aac_adtstoasc",
112    sizeof(AACBSFContext),
113    aac_adtstoasc_filter,
114};
115