Vista Sound Quality Issues with VoIP Apps

Today we had a *fun* time trying to get our application working on Vista. I was so glad Bill Gates was leaving Microsoft which would give Microsoft an opportunity to change. Maybe Gates was meant to be a politician or a banker and thats what he should really focus on. Anyway, let me do the needless by offering you some advice on porting your XP application to Vista. My advice is: GET ON IT!

Our testing on Vista is full of tragedies which include a complete hard disk crash of the Lenovo T61. It seems that hard disk crashes are common on Vista PCs as Vista gets confused about the Boot sector on the disk. Anyway, Lenovo shipped us a new disk and we were able to get back on track in a week. Then the next series of bugs related to VoIP hit us.

Our app uses a VoIP protocol called STUN which is used to traverse NATs. For some reasons STUN clients refuses to work on an Vista PC even after we had the whole Windows firewall turned off. After solving that issue (by basically disabling STUN), we found that while you could play good audio on the PC, the remote end (typically a phone in our case) had poor audio quality. It seems Vista introduces a new module called MMCSS which may be the source of a whole bunch of scheduling and prioritization problems with playing media and network traffic (both of which happen simultaneously in VoIP apps). Completely confused why Windows would do something like this, we started a Skype voice call. While Skype was certainly behaving better, the call quality was not that great and exhibited a lot of noise as well.

Next, we started playing with the Windows XP compatibility settings for our app. God, this was the worst thing to tamper with. Now our application wouldn't even come up. It seems Vista has enough knobs and levers for the average Joe to kill himself!

For people who are getting same issues, I suggest looking at the following pages on the internet and trying out the fixes. We are still working on testing this out.

http://courtneymalone.com/2007/08/28/a-note-on-vista-network-speed/
http://blogs.technet.com/markrussinovich/archive/2007/08/27/1833290.aspx

Vista SP1 is not out yet. Its still in Beta. I recommend going back to XP until SP1 is out.