Hi Folks,
I discovered something new yesterday and just wanted to share it with others. I have an X51 which I upgraded to Windows 8 in October - I've had no problems thus far until I discovered something yesterday as follows:
In my X51 I had thus far left the Realtek HD audio "Waves MAXXAudio" setting in the default "MaxSense On" state which is supposed to improve sound. I decided to turn the Waves MAXXAudio off completely in order the experience my system without all the extra audio processing. To my amazement, Battlefield 3 was a completely new and amazing experience with the default sound (without MAXXAudio enabled I had to up the volume a bit) !! The guns sounded absolutely more powerful and real compared to when MAXXAudio was enabled (I use the Famas BTW :). It turned out that the MaxSense setting has the MaxxLeveler feature turned on by default which dynamically tries to normalize the volume, hence, gunfire in Battlefield 3 was being muffled.
I decided to keep MAXXAudio off and started listening to some music while browsing - then I discovered a problem. Occasionally when I opened a content heavy web-site, I would get a slight click/pop in audio sometimes - this would happen occasionally, but was definitely noticeable. Why did I not notice this earlier when MAXXAudio was ON ? I turned ON MAXXAudio and to my amazement, the click/pop was there - not as pronounced as with the setting turned-off, but it was there. Having MAXXAudio ON reduced the effect of the click/pop, but since I was actually trying to listen for it, I was able to notice it.
Interestingly, with MAXXAudio off, the audio is perfect while on-line gaming in Battlefield 3 - only when browsing the web do I get the occasional clicks.
My research of this problem on-line has pointed to a potential cause: in the way Windows 8 handles interrupts - interrupts is a mechanism used by the OS to communicate with any hardware (mouse, keyboard, audio, video, etc). Speaking broadly, apparently in order to be more power efficient (Windows 8 is optimized to run on Smartphones/Tablets which run on batteries), Windows 8 changes the way interrupts are handled compared with older Windows versions possibly resulting in high latency. This latency, if high enough, can affect real-time tasks such as audio processing resulting in pops/cracks.
There are tools that can expose this high latency. This first tool is DPC Latency checker which is not recommended for Windows 8 as it reports persistently high latency of 1000 uS every second for Windows 8 - the webpage mentions this problem and a fix should be coming soon. The correct tool to use is LatencyMon - I installed and ran it, and lo and behold, there is definitely a latency problem !
I have a screen shot of the LatencyMon window after it captured the high latency event - I simply ran LatencyMon and started browsing the web.
LatencyMon specifies the culprit driver as ndis.sys 6.30 which is the new network driver interface for Windows 8 from Microsoft - the latency is around 19851 us. As indicated in the image, this is most likely related to the WLAN adapter. I have an Intel N6200 wifi installed and I've tried all kinds of things to get rid of the ndis.sys problem - updated drivers, changed, power settings, etc, but no luck. I don't know if the latency is high with the default Dell Artheros Wifi as well.
In order to verify what I have discovered with regards to high latency in Windows 8, could someone with an X51 running Windows 8 please try the following:
1. Turn off MAXXAudio, turn up the volume, start playing some music and start browsing the web. Spend around 10 mins and go to content heavy web-sites - do you notice an occasional pop or click ?
2. Download and run LatencyMon while browsing the web. What latency numbers are being reported ? Are they High ? Similar to what I have ?
It would be good to know if this is a real problem with Windows 8 with regards to the handling of real-time events such as audio.
PS: You may have to run LatencyMon in "administrator mode" in case it refuses to start.
