I have some problems with adpcm in.wav (sound)files. at first of this question, I should say that I didn't read all things about ADPCM, just wanted to implement that fast and work on it... (just training code) I implemented it from MicroChip's pdf guid adpcm .(it's better to say copy/pasted and edited,created class)
Test code:
const std::vector<int8_t> data = {
64, 67, 71, 75, 79, 83, 87, 91, 94, 98, 101, 104, 107, 110, 112,
115, 117, 119, 121, 123, 124, 125, 126, 126, 127, 127, 127, 126, 126, 125,
124, 123, 121, 119, 117, 115, 112, 110, 107, 104, 101, 98, 94, 91, 87,
83, 79, 75, 71, 67, 64, 60, 56, 52, 48, 44, 40, 36, 33, 29,
26, 23, 20, 17, 15, 12, 10, 8, 6, 4, 3, 2, 1, 1, 0,
0, 0, 1, 1, 2, 3, 4, 6, 8, 10, 12, 15, 17, 20, 23,
26, 29, 33, 36, 40, 44, 48, 52, 56, 60, 64};
void function() {
std::vector<uint8_t> en;
std::vector<uint8_t> de;
{ // encode
wave::ADPCM adpcm;
// 32768
for (size_t i{0}; i < data.size() - 3; i += 4) {
int16_t first{static_cast<int16_t>(
~((static_cast<uint16_t>(data[i]) & 0xff) |
((static_cast<uint16_t>(data[i + 1]) << 8) & 0xff00)) +
1)};
int16_t second{static_cast<int16_t>(
~((static_cast<uint16_t>(data[i + 2]) & 0xff) |
((static_cast<uint16_t>(data[i + 3]) << 8) & 0xff00)) +
1)};
en.push_back(static_cast<uint8_t>((adpcm.ADPCMEncoder(first) & 0x0f) |
(adpcm.ADPCMEncoder(second) << 4)));
}
}
{ // decode
wave::ADPCM adpcm;
for (auto val : en) {
int16_t result = ~adpcm.ADPCMDecoder(val & 0xf) + 1;
int8_t temp0 = ((result)&0xff);
int8_t temp1 = ((result)&0xff00) >> 8;
de.push_back(temp0);
de.push_back(temp1);
result = ~adpcm.ADPCMDecoder(val >> 4) + 1;
temp0 = ((result)&0xff);
temp1 = (result & 0xff00) >> 8;
de.push_back(temp0);
de.push_back(temp1);
}
}
int i{0};
for (auto val : de) {
qDebug() << "real:" << data[i] << "decoded: " << val;
i++;
}
}
I'm sure that my class and encode/decode is right,just after decode I should do somethings to show correct numbers(but I donw know which casting is failed) .
why I'm sure? because when I see my output in QDebug, every other sample(after decode) are correct (with few errors, in big datas errors will be smaller than now), but anothers are failed
my output:
real: 26 decoded: 6
real: 29 decoded: 32
real: 33 decoded: 5
real: 36 decoded: 48
real: 40 decoded: 6
real: 44 decoded: 32
real: 48 decoded: 5
real: 52 decoded: 48
real: 56 decoded: 4
real: 60 decoded: 64
data are 8bits in device
Ok, I found my answer
when you have error on any number, your error is in lower bits, so my predict was on two numbers that was anded to gether , then that number is in lower bits position have much errors!
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