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<P><FONT size=4>Hi all,</FONT></P>
<P><FONT size=4>We all know that mismatch between clocks of ADCs of far-end
voice and near-end voice is not allowed in a time-domain or frequency-domain LMS
based AEC system. It means that capture and render audio streams must be
synchronized to a same sample rate. However, I found that this
restriction is removed in microsoft AEC from Windows XP SP1. Anyone knows how
microsoft AEC do it? This technology is much helpful for us to implement AEC in
common PC. We know that most low-cost soundcards have different sample rates in
capturing and rendering which prevents LMS based AEC from being used in most
computer.</FONT></P>
<P><A href="http://msdn.microsoft.com/en-us/library/ff536174(VS.85).aspx"><FONT
size=4>http://msdn.microsoft.com/en-us/library/ff536174(VS.85).aspx</FONT></A><BR><FONT
size=4><EM>In Windows XP, the clock rate must be matched between the capture and
render streams. The AEC system filter implements no mechanism for matching
sample rates across devices. ............. In Windows XP SP1, Windows
Server 2003, and later, this limitation does not exist. The AEC system filter
correctly handles mismatches between the clocks for the capture and render
streams, and separate devices can be used for capture and
rendering.</EM></FONT></P>
<P><FONT size=4>Maoquan</FONT></P></BODY></HTML>