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
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
/*
* Copyright 2003-2021 The Music Player Daemon Project
* http://www.musicpd.org
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License along
* with this program; if not, write to the Free Software Foundation, Inc.,
* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
*/
#include "ChainFilterPlugin.hxx"
#include "filter/Filter.hxx"
#include "filter/Prepared.hxx"
#include "pcm/AudioFormat.hxx"
#include "util/ConstBuffer.hxx"
#include "util/StringBuffer.hxx"
#include "util/RuntimeError.hxx"
#include <cassert>
#include <list>
#include <memory>
#include <string>
class ChainFilter final : public Filter {
struct Child {
std::unique_ptr<Filter> filter;
explicit Child(std::unique_ptr<Filter> &&_filter) noexcept
:filter(std::move(_filter)) {}
};
std::list<Child> children;
/**
* The child which will be flushed in the next Flush() call.
*/
std::list<Child>::iterator flushing = children.end();
public:
explicit ChainFilter(AudioFormat _audio_format)
:Filter(_audio_format) {}
void Append(std::unique_ptr<Filter> filter) noexcept {
assert(out_audio_format.IsValid());
out_audio_format = filter->GetOutAudioFormat();
assert(out_audio_format.IsValid());
children.emplace_back(std::move(filter));
RewindFlush();
}
/* virtual methods from class Filter */
void Reset() noexcept override;
ConstBuffer<void> FilterPCM(ConstBuffer<void> src) override;
ConstBuffer<void> Flush() override;
private:
void RewindFlush() {
flushing = children.begin();
}
};
class PreparedChainFilter final : public PreparedFilter {
struct Child {
const std::string name;
std::unique_ptr<PreparedFilter> filter;
Child(std::string_view _name,
std::unique_ptr<PreparedFilter> _filter)
:name(_name), filter(std::move(_filter)) {}
Child(const Child &) = delete;
Child &operator=(const Child &) = delete;
std::unique_ptr<Filter> Open(const AudioFormat &prev_audio_format);
};
std::list<Child> children;
public:
void Append(std::string_view name,
std::unique_ptr<PreparedFilter> filter) noexcept {
children.emplace_back(name, std::move(filter));
}
/* virtual methods from class PreparedFilter */
std::unique_ptr<Filter> Open(AudioFormat &af) override;
};
std::unique_ptr<Filter>
PreparedChainFilter::Child::Open(const AudioFormat &prev_audio_format)
{
AudioFormat conv_audio_format = prev_audio_format;
auto new_filter = filter->Open(conv_audio_format);
if (conv_audio_format != prev_audio_format)
throw FormatRuntimeError("Audio format not supported by filter '%s': %s",
name.c_str(),
ToString(prev_audio_format).c_str());
return new_filter;
}
std::unique_ptr<Filter>
PreparedChainFilter::Open(AudioFormat &in_audio_format)
{
auto chain = std::make_unique<ChainFilter>(in_audio_format);
for (auto &child : children) {
AudioFormat audio_format = chain->GetOutAudioFormat();
chain->Append(child.Open(audio_format));
}
return chain;
}
void
ChainFilter::Reset() noexcept
{
RewindFlush();
for (auto &child : children)
child.filter->Reset();
}
template<typename I>
static ConstBuffer<void>
ApplyFilterChain(I begin, I end, ConstBuffer<void> src)
{
for (auto i = begin; i != end; ++i)
/* feed the output of the previous filter as input
into the current one */
src = i->filter->FilterPCM(src);
return src;
}
ConstBuffer<void>
ChainFilter::FilterPCM(ConstBuffer<void> src)
{
RewindFlush();
/* return the output of the last filter */
return ApplyFilterChain(children.begin(), children.end(), src);
}
ConstBuffer<void>
ChainFilter::Flush()
{
for (auto end = children.end(); flushing != end; ++flushing) {
auto data = flushing->filter->Flush();
if (!data.IsNull())
return ApplyFilterChain(std::next(flushing), end,
data);
}
return nullptr;
}
std::unique_ptr<PreparedFilter>
filter_chain_new() noexcept
{
return std::make_unique<PreparedChainFilter>();
}
void
filter_chain_append(PreparedFilter &_chain, std::string_view name,
std::unique_ptr<PreparedFilter> filter) noexcept
{
auto &chain = (PreparedChainFilter &)_chain;
chain.Append(name, std::move(filter));
}