- September 1, 2008
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New Zealand
Nice.Well, I unplugged the coax at the cable box side and ran the ATSC scan and I got my channels. Mystery solved.
You have three controls on the AR:Any more info on correcting the aspect ratio on the line-in feed?
1. Potentially the cable box may have an output AR setting somewhere in its settings menu.
2. The tuner input AR setting in TV Server which you already know about (this).
3. There is an aspect ratio setting in MediaPortal. Details.
The order I've listed these is the order that I'd recommend when attempting to solve the problem.
The first setting is the best place to solve the problem. In an ideal world you'd set it as appropriate for the resolution of the source content. The problem is that there may be no setting, or the setting may affect the AR on your TV (which is presumably still hooked up to the cable box). A workaround might be to adjust the TV AR setting such that you get correct AR on the TV and on the PC.
The second setting controls the tuner video scan window size. In an ideal world you'd set it to match the output from the cable box to get optimum picture quality (not that picture quality with an analog RF source will ever be great). However, it may also be used to correct the AR from the cable box if the cable box output is not producing the correct AR. Use trial and error - if one of the values works then go with that. Note that you probably have to restart the TV service for the change to take effect. You may even need to restart the PC (if the tuner driver is really bad).
The third setting is really only designed to be used as a last resort. Even if you can find a mode here that fixes the AR, the setting isn't stored per channel (so you'd have to reset the AR each time you switch to the live feed).
Also, the quality on the line-in feed appearing in my monitor is not as good as on the TV screen. For example, on news channels, the Chyron letters and text in the lower third appears clear and in white on the tv, but with chroma flashing and blur in the computer window.
That is to be expected. Presumably you're using an HDMI connection to the TV? HDMI is vastly superior to an RF feed because it is a digital connection. That means there is no quality loss between the cable box and your TV. With the RF connection to your PC there is a loss in quality:
- in the digital to analog conversion when the source is downscaled and modulated onto the coax cable, simply because this is a lossy process but also because most cable boxes use really cheap digital-to-analog converter chips
- in the cable, simply because the signal is analog and the cable and environment are not electrically noise free (heck, you can pick up ATSC OTA TV using the cable as an aerial)
- in the analog to digital conversion when the signal is demodulated by the tuner, because this is never a lossless process with an analog signal in the real world and most analog tuners have cheap analog-to-digital conversion chips
- on the tuner PC and motherboard as the signal is routed through the PC, because a PC is a very noisy electrical environment
- in the ATI software encoders which throw away some of the detail when they compress the source into MPEG 2 video and audio
mm
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