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Old 10-26-06, 08:57 PM   #16
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Join Date: Oct 2006
Posts: 2
Default Re: nVidia driver corrupts pcHDTV 3000 mpeg stream

Originally Posted by netllama
Earlier in a related thread, someone stated that the corruption also was present when using the 'nv' driver. That suggests that this is not an nvidia driver bug, but more likely a hardware issue.
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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