QWindowsResampler: overallocate output bufferHEADdev

The estimation based on duration does incur rounding errors, which can
lead us to call IMFTransform::ProcessOutput more than necessary. so we
slightly overallocate the output buffer, as that will avoid unnecessary
calls.

Pick-to: 6.8 6.9 6.10
Change-Id: Ic259022e4adaf018d0fa4780c3f2b4174d99c322
Reviewed-by: Artem Dyomin <[email protected]>

1 files changed, 5 insertions, 0 deletions

diff --git a/src/multimedia/windows/qwindowsresampler.cpp b/src/multimedia/windows/qwindowsresampler.cpp
index 5a1fec8d0..f172579da 100644
--- a/src/multimedia/windows/qwindowsresampler.cpp
+++ b/src/multimedia/windows/qwindowsresampler.cpp
@@ -5,6 +5,7 @@
 
 #include <QtCore/qloggingcategory.h>
 #include <QtCore/private/qsystemerror_p.h>
+#include <QtMultimedia/private/qaudio_alignment_support_p.h>
 #include <QtMultimedia/private/qwindowsaudioutils_p.h>
 
 #include <wmcodecdsp.h>
@@ -92,6 +93,10 @@ HRESULT QWindowsResampler::processOutput(QByteArray &out)
 
     if (m_resamplerNeedsSampleBuffer) {
         auto expectedOutputSize = outputBufferSize(m_totalInputBytes) - m_totalOutputBytes;
+        // we may have some rounding errors, so we over-allocate by 10ms
+        expectedOutputSize += m_outputFormat.bytesForDuration(10000);
+        expectedOutputSize = QtMultimediaPrivate::alignUp(expectedOutputSize, 1024);
+
         HRESULT hr = m_wmf->mfCreateMemoryBuffer(expectedOutputSize, buffer.GetAddressOf());
         if (FAILED(hr))
             return hr;