Over the last couple of weeks the dialog volume was extremely low on several prime time shows on WDIV Detroit digital. Of course my first thought was that it was the fault of the 921 but, after talking to WDIV engineeering today, they are having problems with a new Dolby 5.1 encoder on their digital transmitter. This caused the center channel (where most of the spoken dialog is to drop out. Also some times the audio stream coming from the network digital signal was low and they chose to up-res the SD signal from the net to broadcast digitally. In those instances the audio was normal but the picture was 4x3. Interesting I thought and NOT a bug in the DVR. WHEW!!! 
