2) Sudden sound drop - At random times the sound (we've only noticed watching OTA TV) drops and we need to increase it
Try adjusting Options > Video > Adaptive Volume.
The default setting is "light". This is really not completely aptly named, as it doesn't really do "processing" on the audio's dynamic range, but instead tries to increase it to the proper volume (without going over). This is often useful because many AC3 tracks ripped from DVD are terribly quiet (only using the lower end of the available dynamic range), especially when compared with the results of the Loudness War for popular music (only using the high end of the available dynamic range).
However... With badly encoded audio files embedded in video, I've seen problems where this gets confused. The problem is that the Adaptive Volume system also tries to be "safe" and prevent clipping, and with files with stream errors, it sometimes freaks out and thinks there are sudden, transient peaks in the audio, and drops the volume way down.
Many TV Tuners and video capture devices, particularly consumer ones, don't produce very nicely encoded files. And, frankly, neither do most cable broadcasters (not to mention line loss and digital errors introduced during transmission, through space and miles and miles of cable), so it would make sense that you might be seeing the same thing here.
I'd try a few things:
1. Play with the Adaptive Volume control and see if you can make it better. Medium, for example, will compress the dynamic range (hurting quality), but can make troublesome videos much more easy to hear. You can also disable the adaptive volume system entirely.
2. Check for driver updates for your capture card, and make sure your connection is solid (loose cables seem to dramatically impact both my analog and QAM tuners).
3. See if it impacts certain channels more than others. In my case, Comedy Central and A&E are so full of errors in the audio tracks that my Denon won't decode the AC3 properly at all (if I bitstream or hook the cable directly to the receiver via SPDIF). Other channels seem unaffected, and switching MC to let
it decode the AC3 streams works much better. In any case, you might be able to find certain other correlations that are channel specific. Then, at least, you know what you're in for, and can maybe activate the Medium Adaptive Volume (or turn it off, whichever works best) for those files.
The adaptive volume control is Zone-specific, so if you want a quick way to switch between them, you can make a duplicate of your existing Zone (manually, unfortunately) and change only Adaptive Volume to whatever alternative you want. Then, you can quickly and painlessly switch back and forth (especially if you add the Zones toolbar button somewhere).
