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Old 10-27-06, 12:57 PM   #18
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Join Date: Aug 2006
Posts: 7
Default Re: nVidia driver corrupts pcHDTV 3000 mpeg stream

so why would this noise issue only affect the pchdtv-5500 and not the hd-5000 which are both present in my setup? is the hd-5000 not as susceptible to noise?

Originally Posted by xyzzy42
I have this same problem with QAM reception and the HD-3000. It does NOT occur when using the 'nv' driver, only with the 'nvidia' driver. There have been quite a few posts on this at the pcHDTV forum.

"Video corruption" is a very vague problem. It could be a million things, known bugs in mplayer, dma buffer overflows, irqs getting dropped, etc.

This problem is video activity using the nvidia driver causes the demodulator to lose its signal lock. That in turns corrupts the mpeg stream.

It doesn't appear to effect 8-VSB reception, only QAM. Note that 8-VSB needs a much lower signal-to-noise ratio than 256-QAM for quasi-error-free reception.

I'm pretty sure that it is related to noise on the power supply rails created by the nvidia video card (FX5200 in my case). Something the nvidia driver does creates more noise than the nv driver. It does not appear to be any kind of buffer overflow (not the dvb layer dvr buffer, the cx88 DMA buffers, or the cx88's internal FIFO. Some people do have problems with those things, but that is a different issue).
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