White Pixels

[ryandude_12345]

I don't really know if I'm in the right place but anyways... On Rogers HD channels (some) I notice on some commercials and movies playing on the channel that there are white pixel like parts on the top or bottom of the screen, does anyone know how to fix this issue, it's really annoying! Thanks in advance

[dcorreia]

I'm noticing a whole lotta white dots on GlobalTV's coverage of the grammy's compared to CBS feed.

Both stations I'm receiving over-the-air though.

[ryandude_12345]

That's what I'm watching too, it seems whenever there is a commercial with black bars or SD commercials, the white pixels always show up! I don't like it!

[msgohan]

http://en.wikipedia.org/wiki/Vertical_blanking_interval

It's a failure on the part of the broadcasters to align the image to show only the active area. Pretty much the only thing you as a viewer can do is crop it by enabling Overscan on your display (turn off 1:1 pixel mapping).

[57]

Here's the FAQ with the explanation and the workarounds - switch to 16:9/Full stretch instead of 1:1 pixel mapping (0% overscan): My guess is that you are on the zero percent overscan mode of your TV and that the affiliate has not properly centered the image - as discussed in the FAQ link below and in the post above.

http://www.digitalhome.ca/forum/show...236#post793236

[ryandude_12345]

Thanks everyone! I noticed that my samsung tv was on screen fit mode, so I put it to 16:9, it's gone now, but the only bad part it that it cuts of about 1 inch of the picture.. I hope the broadcasters fix this issue

[57]

Once everything's HD there should be fewer such issues, however, this happens a lot with upconverts, unfortunately. You aren't actually "missing" any of the programming since the spec for HD broadcast is 3% overscan. Here's the FAQ on Overscan:

http://www.digitalhome.ca/forum/showthread.php?t=93233

[JamesK]

It's a failure on the part of the broadcasters to align the image to show only the active area.

That link you provided is about the Vertical Blanking Interval (VBI), which is used only on analog signals and, with digital TV, should only be visible on signals improperly converted from analog. There is some other cause of that sort of noise on digital signals, as I have seen it on original HD content as well.

[57]

JamesK, you bring up that argument every time we discuss this topic. It's still VBI "junk" that's left over from the analogue SD programme after upconversion; even though it is then distributed on a digital channel, which obviously doesn't actually contain VBI. For example:

http://www.digitalhome.ca/forum/show...54#post1280154

[JamesK]

I mention it because others continually refer to it, even though there's no VBI in digital signals. Yes, there's VBI in analog broadcasts. That VBI info is inserted on analog broadcasts only and may appear when that analog signal is converted. It is not in the video signal from video tape, as that blanking time is used for head switching in the recorder. The VBI data is inserted at the time of broadcast. This means the noise comes from elsewhere and not related to VBI, even though it may look like it. As I mentioned, I have seen that on original 16:9 HD content, which was not converted from an analog. Unless the signal has been converted from a broadcast analog signal, it's not VBI and calling it such is just as wrong as talking about analog record artifacts on an CD that was never mastered in analog.
Once again, if the digital signal did not originate on an analog broadcast, it's not VBI. To claim otherwise is to provide misinformation.

[57]

I get your point. On some channels it looks exactly like VBI, therefore can we call it VBI-like (as mentioned in my FAQ)? Regardless, the issue comes from zero overscan on the TV (and broadcast misalignment), and can be resolved by using the 16:9/Full setting which we mentioned in this thread, and the OP now understands.