1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
|
/* ------------------------------------------------------------------
* Copyright (C) 2011 Martin Storsjo
* Copyright (C) 2017 Matthias P. Braendli
* Copyright (C) 2016 Stefan Pöschel
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either
* express or implied.
* See the License for the specific language governing permissions
* and limitations under the License.
* -------------------------------------------------------------------
*/
#include "config.h"
#include "AACDecoder.h"
#include <stdexcept>
#include <string>
AACDecoder::AACDecoder(const char* wavfilename) :
m_wav_writer(wavfilename)
{
m_handle = aacDecoder_Open(TT_MP4_RAW, 1);
if (not m_handle) {
throw std::runtime_error("AACDecoder: error opening decoder");
}
}
void AACDecoder::decode_frame(uint8_t *data, size_t len)
{
const bool dac_rate = data[2] & 0x40;
const bool sbr_flag = data[2] & 0x20;
const bool aac_channel_mode = data[2] & 0x10;
const bool ps_flag = data[2] & 0x08;
const uint8_t mpeg_surround_config = data[2] & 0x07;
const int core_sr_index = dac_rate ?
(sbr_flag ? 6 : 3) : (sbr_flag ? 8 : 5); // 24/48/16/32 kHz
const int core_ch_config = aac_channel_mode ? 2 : 1;
const int extension_sr_index = dac_rate ? 3 : 5; // 48/32 kHz
int au_start[6] = {};
int num_aus = dac_rate ? (sbr_flag ? 3 : 6) : (sbr_flag ? 2 : 4);
au_start[0] = dac_rate ? (sbr_flag ? 6 : 11) : (sbr_flag ? 5 : 8);
au_start[1] = data[3] << 4 | data[4] >> 4;
if (num_aus >= 3) {
au_start[2] = (data[4] & 0x0F) << 8 | data[5];
}
if (num_aus >= 4) {
au_start[3] = data[6] << 4 | data[7] >> 4;
}
if (num_aus == 6) {
au_start[4] = (data[7] & 0x0F) << 8 | data[8];
au_start[5] = data[9] << 4 | data[10] >> 4;
}
au_start[num_aus] = len; // end of the buffer
for (int i = 0; i < num_aus; i++) {
if (au_start[i] >= au_start[i+1]) {
throw std::runtime_error(" AU ordering check failed\n");
}
}
if (not m_decoder_set_up) {
std::vector<uint8_t> asc;
// AAC LC
asc.push_back(0b00010 << 3 | core_sr_index >> 1);
asc.push_back((core_sr_index & 0x01) << 7 | core_ch_config << 3 | 0b100);
if (sbr_flag) {
// add SBR
asc.push_back(0x56);
asc.push_back(0xE5);
asc.push_back(0x80 | (extension_sr_index << 3));
if (ps_flag) {
// add PS
asc.back() |= 0x05;
asc.push_back(0x48);
asc.push_back(0x80);
}
}
uint8_t* asc_array[1] {asc.data()};
const unsigned int asc_sizeof_array[1] {(unsigned int) asc.size()};
AAC_DECODER_ERROR init_result = aacDecoder_ConfigRaw(m_handle,
asc_array, asc_sizeof_array);
if (init_result != AAC_DEC_OK) {
throw std::runtime_error(
"AACDecoderFDKAAC: error while aacDecoder_ConfigRaw: " +
std::to_string(init_result));
}
m_channels = (aac_channel_mode or ps_flag) ? 2 : 1;
size_t output_frame_len = 960 * 2 * m_channels * (sbr_flag ? 2 : 1);
m_output_frame.resize(output_frame_len);
fprintf(stderr, " Setting decoder output frame len %zu\n", output_frame_len);
const int sample_rate = dac_rate ? 48000 : 32000;
m_wav_writer.initialise_header(sample_rate, m_channels);
m_decoder_set_up = true;
fprintf(stderr, " Set up decoder with %d Hz, %s%swith %d channels\n",
sample_rate, (sbr_flag ? "SBR " : ""), (ps_flag ? "PS " : ""),
m_channels);
}
const size_t AU_CRCLEN = 2;
for (int i = 0; i < num_aus; i++) {
uint8_t *au_data = data + au_start[i];
size_t au_len = au_start[i+1] - au_start[i] - AU_CRCLEN;
decode_au(au_data, au_len);
}
}
void AACDecoder::decode_au(uint8_t *data, size_t len)
{
uint8_t* input_buffer[1] {data};
const unsigned int input_buffer_size[1] {(unsigned int) len};
unsigned int bytes_valid = len;
// fill internal input buffer
AAC_DECODER_ERROR result = aacDecoder_Fill(
m_handle, input_buffer, input_buffer_size, &bytes_valid);
if (result != AAC_DEC_OK) {
throw std::runtime_error(
"AACDecoderFDKAAC: error while aacDecoder_Fill: " +
std::to_string(result));
}
if (bytes_valid) {
throw std::runtime_error(
"AACDecoderFDKAAC: aacDecoder_Fill did not consume all bytes");
}
// decode audio
result = aacDecoder_DecodeFrame(m_handle,
(short int*)m_output_frame.data(), m_output_frame.size(), 0);
if (result != AAC_DEC_OK) {
throw std::runtime_error(
"AACDecoderFDKAAC: error while aacDecoder_DecodeFrame: " +
std::to_string(result));
}
m_wav_writer.write_data(m_output_frame.data(), m_output_frame.size());
}
|
