engine: sound: allow cubic sound interpolation

engine/client/s_mix.c

@@ -792,8 +792,6 @@ void S_MixBufferUpsample2x( int count, portable_samplepair_t *pbuffer, portable_
 		pbuffer[i-1] = pbuffer[j];
 	}
 
-	if( !s_lerping->value ) return;
-	
 	// pass forward through buffer, interpolate all even slots
 	switch( filtertype )
 	{
@@ -993,7 +991,7 @@ void MIX_UpsampleAllPaintbuffers( int end, int count )
 	// upsample all 11khz buffers by 2x
 	// only upsample roombuffer if dsp fx are on KDB: perf
 	MIX_SetCurrentPaintbuffer( IROOMBUFFER ); // operates on MixUpSample
-	S_MixUpsample( count / (SOUND_DMA_SPEED / SOUND_11k), FILTERTYPE_LINEAR ); 
+	S_MixUpsample( count / ( SOUND_DMA_SPEED / SOUND_11k ), s_lerping->value );
 
 	// mix 22khz sounds: 
 	MIX_MixChannelsToPaintbuffer( end, SOUND_22k, SOUND_22k );
@@ -1001,7 +999,7 @@ void MIX_UpsampleAllPaintbuffers( int end, int count )
 	// upsample all 22khz buffers by 2x
 	// only upsample roombuffer if dsp fx are on KDB: perf
 	MIX_SetCurrentPaintbuffer( IROOMBUFFER );
-	S_MixUpsample( count / ( SOUND_DMA_SPEED / SOUND_22k ), FILTERTYPE_LINEAR );
+	S_MixUpsample( count / ( SOUND_DMA_SPEED / SOUND_22k ), s_lerping->value );
 
 	// mix all 44khz sounds to all active paintbuffers
 	MIX_MixChannelsToPaintbuffer( end, SOUND_44k, SOUND_DMA_SPEED );