PVS-Studio warning V547 for IPP Samples

Ipp32u m_iCurrMBIndex;

VC1EncoderMBInfo *
VC1EncoderMBs::GetPevMBInfo(Ipp32s x, Ipp32s y)
{
   Ipp32s row = (y>0)? m_iPrevRowIndex:m_iCurrRowIndex;
   return ((m_iCurrMBIndex - x <0 || row <0) ?
          0 :
          &m_MBInfo[row][m_iCurrMBIndex - x]);
}

Since the check doesn't work, we may easily get an array overrun.

This suspicious code was found in IPP Samples project by PVS-Studio static code analyzer.
Warning message is:
V547 Expression 'm_iCurrMBIndex - x < 0' is always false. Unsigned type value is never < 0. vc1_enc umc_vc1_enc_mb.cpp 188

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