Error in reading wav-file header

[davidlamhauge]

I didn't know about qFromLittleEndian().
I have read about, but can't make it work. Could you give me a hint on how to use in my context?

And - it still puzzles me that the the function GetLittleEndianInteger returns a negative samplerate.
I tried to debug, and the value of my QByteArray tst, shows that 0xAC is read as '-84 / 172' (see image)
debug_qbytearray.jpg
Why?

[wysota]

I didn't know about qFromLittleEndian().
I have read about, but can't make it work. Could you give me a hint on how to use in my context?

Read four bytes, cast them to uchar* and pass to qFromLittleEndian().

[davidlamhauge]

Read four bytes, cast them to uchar* and pass to qFromLittleEndian().

Is it possible to elaborate a little?
I've tried many combinations, and read many posts on the net, but...
Is it like this you mean?

audioFil.seek(24);
        tst = audioFil.read(4);
        tst[0] = (uchar)tst[0];
        tst[1] = (uchar)tst[1];
        tst[2] = (uchar)tst[2];
        tst[3] = (uchar)tst[3];
        sampleRate = qFromLittleEndian<quint32>(*tst);
//        sampleRate = GetLittleEndianInteger(tst,0);
        qDebug() << "sampleRate: " << sampleRate;

audioFil.seek(24);
        tst = audioFil.read(4);
        tst[0] = (uchar)tst[0];
        tst[1] = (uchar)tst[1];
        tst[2] = (uchar)tst[2];
        tst[3] = (uchar)tst[3];
        sampleRate = qFromLittleEndian<quint32>(*tst);
//        sampleRate = GetLittleEndianInteger(tst,0);
        qDebug() << "sampleRate: " << sampleRate;

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The debug-output is 'sampleRate: 68'. 68 = 'D' = tst[0].
I don't really get it. Hence 'Beginner'...

EDITED:
when I read my reply it dawned a little. This works:

uchar* cc;
        audioFil.seek(24);
        tst = audioFil.read(4);
        cc[0] = tst[0];
        cc[1] = tst[1];
        cc[2] = tst[2];
        cc[3] = tst[3];
        sampleRate = qFromLittleEndian<qint32>(cc);
//        sampleRate = GetLittleEndianInteger(tst,0);
        qDebug() << "sampleRate: " << sampleRate;

uchar* cc;
        audioFil.seek(24);
        tst = audioFil.read(4);
        cc[0] = tst[0];
        cc[1] = tst[1];
        cc[2] = tst[2];
        cc[3] = tst[3];
        sampleRate = qFromLittleEndian<qint32>(cc);
//        sampleRate = GetLittleEndianInteger(tst,0);
        qDebug() << "sampleRate: " << sampleRate;

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...but could it be done more effectively?

[wysota]

QByteArray ba = audoFil.read(4);
qint32 sampleRate = qFromLittleEndian((const uchar*)ba.constData());

QByteArray ba = audoFil.read(4);
qint32 sampleRate = qFromLittleEndian((const uchar*)ba.constData());

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