XAudio2 upmixing matrices
Posted: Mon Jul 14, 2008 1:45 pm
Hey there, I just added the feature to upmix the GB's/GBA's stereo sound to the number of speakers which are attached to the souncard.
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I took this inof sheet as a reference:
http://ac3filter.net/guides/mixing_matrix
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And this for the speaker order:
http://msdn.microsoft.com/en-us/library/bb694506.aspx
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Here are my matrices. Since I entered them by hand, it would be good if everyone who is into that stuff could tell me if they're good.
Is it OK if I leave the LFE always at 0 since it would receive frequencies higher than for ex. 120Hz?
I can still hear my LFE because my sound driver uses a crossover frequency to get the subwoofer signal from the low-freq part of the other channels.
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Code: Select all
#ifdef STEREO_UPMIXING
// set up stereo upmixing
XAUDIO2_DEVICE_DETAILS dd;
ZeroMemory( &dd, sizeof( dd ) );
hr = xaud->GetDeviceDetails( 0, &dd );
ASSERT( hr == S_OK );
float *matrix = NULL;
matrix = (float*)malloc( sizeof( float ) * 2 * dd.OutputFormat.Format.nChannels );
switch( dd.OutputFormat.Format.nChannels ) {
case 4: // 4.0
//Speaker \ Left Source Right Source
/*Front L*/ matrix[0] = 1.0000f; matrix[1] = 0.0000f;
/*Front R*/ matrix[2] = 0.0000f; matrix[3] = 1.0000f;
/*Back L*/ matrix[4] = 1.0000f; matrix[5] = 0.0000f;
/*Back R*/ matrix[6] = 0.0000f; matrix[7] = 1.0000f;
break;
case 5: // 5.0
//Speaker \ Left Source Right Source
/*Front L*/ matrix[0] = 1.0000f; matrix[1] = 0.0000f;
/*Front R*/ matrix[2] = 0.0000f; matrix[3] = 1.0000f;
/*Front C*/ matrix[4] = 0.7071f; matrix[5] = 0.7071f;
/*Side L*/ matrix[6] = 1.0000f; matrix[7] = 0.0000f;
/*Side R*/ matrix[8] = 0.0000f; matrix[9] = 1.0000f;
break;
case 6: // 5.1
//Speaker \ Left Source Right Source
/*Front L*/ matrix[0] = 1.0000f; matrix[1] = 0.0000f;
/*Front R*/ matrix[2] = 0.0000f; matrix[3] = 1.0000f;
/*Front C*/ matrix[4] = 0.7071f; matrix[5] = 0.7071f;
/*LFE */ matrix[6] = 0.0000f; matrix[7] = 0.0000f;
/*Side L*/ matrix[8] = 1.0000f; matrix[9] = 0.0000f;
/*Side R*/ matrix[10] = 0.0000f; matrix[11] = 1.0000f;
break;
case 7: // 6.1
//Speaker \ Left Source Right Source
/*Front L*/ matrix[0] = 1.0000f; matrix[1] = 0.0000f;
/*Front R*/ matrix[2] = 0.0000f; matrix[3] = 1.0000f;
/*Front C*/ matrix[4] = 0.7071f; matrix[5] = 0.7071f;
/*LFE */ matrix[6] = 0.0000f; matrix[7] = 0.0000f;
/*Side L*/ matrix[8] = 1.0000f; matrix[9] = 0.0000f;
/*Side R*/ matrix[10] = 0.0000f; matrix[11] = 1.0000f;
/*Back C*/ matrix[12] = 0.7071f; matrix[13] = 0.7071f;
break;
case 8: // 7.1
//Speaker \ Left Source Right Source
/*Front L*/ matrix[0] = 1.0000f; matrix[1] = 0.0000f;
/*Front R*/ matrix[2] = 0.0000f; matrix[3] = 1.0000f;
/*Front C*/ matrix[4] = 0.7071f; matrix[5] = 0.7071f;
/*LFE */ matrix[6] = 0.0000f; matrix[7] = 0.0000f;
/*Back L*/ matrix[8] = 1.0000f; matrix[9] = 0.0000f;
/*Back R*/ matrix[10] = 0.0000f; matrix[11] = 1.0000f;
/*Side L*/ matrix[12] = 1.0000f; matrix[13] = 0.0000f;
/*Side R*/ matrix[14] = 0.0000f; matrix[15] = 1.0000f;
break;
}
hr = sVoice->SetOutputMatrix( NULL, 2, dd.OutputFormat.Format.nChannels, matrix );
ASSERT( hr == S_OK );
free( matrix );
matrix = NULL;
#endif
