Random "Flashing" on DVB-T2 in UK

[CyberSimian]

At the moment I have a single TBS 6284 quad-tuner card in my HTPC. It is a fresh install of Windows 7, with all maintenance applied. I am using version 1.0.0.3 of the TBS driver, and watching TV using Windows Media Center. The graphics card is an Nvidia 8400GS, and the drivers are version 301.42 (the most-recent WHQL-certified drivers).

DVB-T broadcasts are received satisfactorily; the problem is with the DVB-T2 broadcasts (there is one DVB-T2 MUX in the UK, currently carrying 5 high-definition channels). Randomly, the screen will briefly lighten (similar to the effect seen when a flashgun on a camera is discharged in the field of view of a TV camera). The time between flashes can be as short as one second, but can also be longer; it seems to vary randomly. I have checked all of the 5 HD channels, and they all exhibit this effect, although the severity of the effect does vary from day to day, and from channel to channel. So that you can get a better idea of the effect, I have recorded a brief sequence from the Olympic games, which you can download from my web site. It is circa 14 seconds long, and 11MB in size; there are around 5 flashes in this 14-second clip:

http://www.xenscape.com/anon/olympic_archery.wtv

Out of interest, I installed the latest version of the TBSviewer program. It is not as easy to set up as Media Center, but when I did get it going I was surprised to find that TBSviewer does not exhibit the flashing effect -- the high definition channels seem to be as good as they should be.

Any ideas as to the cause of the flashing? Something wrong with my setup, or a bug in the software?

-- from CyberSimian in the UK

[CyberSimian]

Some discussions on another forum indicated that the problem might be caused by the Nvidia drivers. I was using version 301.42 (WHQL certified), so I downloaded and installed version 304.79 (a beta version), and this seems to have fixed the problem. Panic over!

-- from CyberSimian in the UK

[MrE]

Slight thread revival.

I have just purchased a 6284 card and I get exactly the symptoms described by Simon above.
A random 'flash' on UK freeview HD channels.
SD channels do not exhibit this issue.
Other HD sources (internet streams, BluRay) do not exhibit this issue.

I'm not using a GFX card, I'm running on board graphics (Intel 4600 with latest drivers).
I'm running 1.0.0.7 drivers which I believe are latest?

I'm happy to take beta/patched drivers if it helps debug the issue.

Any thoughts from the community?

[CyberSimian]

I have just purchased a 6284 card and I get exactly the symptoms described above. A random 'flash' on UK freeview HD channels. SD channels do not exhibit this issue. Other HD sources (internet streams, BluRay) do not exhibit this issue.

Since my original post, I have changed graphics cards, and I currently use an Nvidia GT610. The Nvidia drivers that I was using with the 8400GS did not support the GT610, so I installed some newer drivers, only to find that the flashing problem returned! I then tried yet more versions of the Nvidia drivers, and thankfully found a set that supports the GT610 and does not flash on DVB-T2 broadcasts.

I believe that the generally accepted wisdom is that this problem is caused by the drivers for the graphics adapter (separate card or built-in on the motherboard), and is not due to the drivers for the TBS card. I do not have any experience using Intel built-in graphics, but I think that you should experiment with different settings in the Intel graphics software. Specifically, try disabling one by one all of the "image enhancement" settings to see which may be causing the problem. "Dynamic contrast enhancement" is one that has caused other users problems, I think.

-- from CyberSimian in the UK