Aggressively round up to the proper alignment when reporting position

dlls/winmm/wavemap/wavemap.c

@@ -418,14 +418,59 @@ static	DWORD	wodUnprepare(WAVEMAPDATA* wom, LPWAVEHDR lpWaveHdrSrc, DWORD dwPara
 static	DWORD	wodGetPosition(WAVEMAPDATA* wom, LPMMTIME lpTime, DWORD dwParam2)
 {
     DWORD       val;
+    MMTIME      timepos;
     TRACE("(%p %p %08lx)\n", wom, lpTime, dwParam2);
 
-    val = waveOutGetPosition(wom->u.out.hInnerWave, lpTime, dwParam2);
-    if (lpTime->wType == TIME_BYTES)
-        lpTime->u.cb = MulDiv(lpTime->u.cb, wom->avgSpeedOuter, wom->avgSpeedInner);
-    if (lpTime->wType == TIME_SAMPLES)
-        lpTime->u.cb = MulDiv(lpTime->u.cb, wom->nSamplesPerSecOuter, wom->nSamplesPerSecInner);
+    memcpy(&timepos, lpTime, sizeof(timepos));
+
+    /* For TIME_MS, we're going to recalculate using TIME_BYTES */
+    if (lpTime->wType == TIME_MS)
+        timepos.wType = TIME_BYTES;
+
+    val = waveOutGetPosition(wom->u.out.hInnerWave, &timepos, dwParam2);
+
+    if (lpTime->wType == TIME_BYTES || lpTime->wType == TIME_MS)
+    {
+        DWORD dwInnerSamplesPerOuter = wom->nSamplesPerSecInner / wom->nSamplesPerSecOuter;
+        if (dwInnerSamplesPerOuter > 0)
+        {
+            DWORD dwInnerBytesPerSample = wom->avgSpeedInner / wom->nSamplesPerSecInner;
+            DWORD dwInnerBytesPerOuterSample = dwInnerBytesPerSample * dwInnerSamplesPerOuter;
+            DWORD remainder = 0;
+
+            /* If we are up sampling (going from lower sample rate to higher),
+            **   we need to make a special accomodation for times when we've
+            **   written a partial output sample.  This happens frequently
+            **   to us because we use msacm to do our up sampling, and it
+            **   will up sample on an unaligned basis.
+            ** For example, if you convert a 2 byte wide 8,000 'outer'
+            **   buffer to a 2 byte wide 48,000 inner device, you would
+            **   expect 2 bytes of input to produce 12 bytes of output.
+            **   Instead, msacm will produce 8 bytes of output.
+            **   But reporting our position as 1 byte of output is
+            **   nonsensical; the output buffer position needs to be
+            **   aligned on outer sample size, and aggressively rounded up.
+            */
+            remainder = timepos.u.cb % dwInnerBytesPerOuterSample;
+            if (remainder > 0)
+            {
+                timepos.u.cb -= remainder;
+                timepos.u.cb += dwInnerBytesPerOuterSample;
+            }
+        }
+
+        lpTime->u.cb = MulDiv(timepos.u.cb, wom->avgSpeedOuter, wom->avgSpeedInner);
+
+        /* Once we have the TIME_BYTES right, we can easily convert to TIME_MS */
+        if (lpTime->wType == TIME_MS)
+            lpTime->u.cb = MulDiv(lpTime->u.cb, 1000, wom->avgSpeedOuter);
+    }
+    else if (lpTime->wType == TIME_SAMPLES)
+        lpTime->u.cb = MulDiv(timepos.u.cb, wom->nSamplesPerSecOuter, wom->nSamplesPerSecInner);
+    else
         /* other time types don't require conversion */
+        lpTime->u = timepos.u;
+
     return val;
 }