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
|
/*
* SampleFormatBRR.cpp
* -------------------
* Purpose: BRR (SNES Bit Rate Reduction) sample format import.
* Notes : This format has no magic bytes, so frame headers are thoroughly validated.
* Authors: OpenMPT Devs
* The OpenMPT source code is released under the BSD license. Read LICENSE for more details.
*/
#include "stdafx.h"
#include "Sndfile.h"
#include "../common/FileReader.h"
OPENMPT_NAMESPACE_BEGIN
static void ProcessBRRSample(int32 sample, int16 *output, uint8 range, uint8 filter)
{
if(sample >= 8)
sample -= 16;
if(range <= 12)
sample = mpt::rshift_signed(mpt::lshift_signed(sample, range), 1);
else
sample = (sample < 0) ? -2048 : 0; // Implementations do not fully agree on what to do in this case. This is what bsnes does.
// Apply prediction filter
// Note 1: It is okay that we may access data before the first sample point because this memory is reserved for interpolation
// Note 2: The use of signed shift arithmetic is crucial for some samples (e.g. killer lead.brr, Mac2.brr)
// Note 3: Divisors are twice of what is written in the respective comments, as all sample data is divided by 2 (again crucial for accuracy)
static_assert(InterpolationLookaheadBufferSize >= 2);
switch(filter)
{
case 1: // y(n) = x(n) + x(n-1) * 15/16
sample += mpt::rshift_signed(output[-1] * 15, 5);
break;
case 2: // y(n) = x(n) + x(n-1) * 61/32 - x(n-2) * 15/16
sample += mpt::rshift_signed(output[-1] * 61, 6) + mpt::rshift_signed(output[-2] * -15, 5);
break;
case 3: // y(n) = x(n) + x(n-1) * 115/64 - x(n-2) * 13/16
sample += mpt::rshift_signed(output[-1] * 115, 7) + mpt::rshift_signed(output[-2] * -13, 5);
break;
}
sample = std::clamp(sample, int32(-32768), int32(32767)) * 2;
if(sample > 32767)
sample -= 65536;
else if(sample < -32768)
sample += 65536;
output[0] = static_cast<int16>(sample);
}
bool CSoundFile::ReadBRRSample(SAMPLEINDEX sample, FileReader &file)
{
const auto fileSize = file.GetLength();
if(fileSize < 9 || fileSize > uint16_max)
return false;
const bool hasLoopInfo = (fileSize % 9) == 2;
if((fileSize % 9) != 0 && !hasLoopInfo)
return false;
file.Rewind();
SmpLength loopStart = 0;
if(hasLoopInfo)
{
loopStart = file.ReadUint16LE();
if(loopStart >= fileSize)
return false;
if((loopStart % 9) != 0)
return false;
}
// First scan the file for validity and consistency
// Note: There are some files with loop start set but ultimately the loop is never enabled. Cannot use this as a consistency check.
// Very few files also have a filter set on the first block, so we cannot reject those either.
bool enableLoop = false, first = true;
while(!file.EndOfFile())
{
const auto block = file.ReadArray<uint8, 9>();
const bool isLast = (block[0] & 0x01) != 0;
const bool isLoop = (block[0] & 0x02) != 0;
const uint8 range = block[0] >> 4u;
if(isLast != file.EndOfFile())
return false;
if(!first && enableLoop != isLoop)
return false;
// While a range of 13 is technically invalid as well, it can be found in the wild.
if(range > 13)
return false;
enableLoop = isLoop;
first = false;
}
file.Seek(hasLoopInfo ? 2 : 0);
DestroySampleThreadsafe(sample);
ModSample &mptSmp = Samples[sample];
mptSmp.Initialize();
mptSmp.uFlags = CHN_16BIT;
mptSmp.nLength = mpt::saturate_cast<SmpLength>((fileSize - (hasLoopInfo ? 2 : 0)) * 16 / 9);
if(enableLoop)
mptSmp.SetLoop(loopStart * 16 / 9, mptSmp.nLength, true, false, *this);
mptSmp.nC5Speed = 32000;
m_szNames[sample] = "";
if(!mptSmp.AllocateSample())
return false;
int16 *output = mptSmp.sample16();
while(!file.EndOfFile())
{
const auto block = file.ReadArray<uint8, 9>();
const uint8 range = block[0] >> 4u;
const uint8 filter = (block[0] >> 2) & 0x03;
for(int i = 0; i < 8; i++)
{
ProcessBRRSample(block[i + 1] >> 4u, output, range, filter);
ProcessBRRSample(block[i + 1] & 0x0F, output + 1, range, filter);
output += 2;
}
}
mptSmp.Convert(MOD_TYPE_IT, GetType());
mptSmp.PrecomputeLoops(*this, false);
return true;
}
OPENMPT_NAMESPACE_END
|
