Shimmering haloes and lines on digital, analogue, film based

[Ben Wiens]

I noticed that when my digital video is viewed on a TV or monitor there is some shimmering of object edges. My camcorder is the highly rated 1CCD Panasonic PV-DV852 (like NV-MX8). I didn't edit the footage at all. For example slight panning of a fence with vertical boards results in a type of moving strobe effect sometimes with rainbow colors. Moving cars having a shimmering halo around them.

I reviewed some footage of my dad's analogue 1CCD video and same thing. He had been wondering about this.

Video tapes that I rent of popular movies which were originally shot in 35 mm film don't seem to have this problem at all.

Is this the difference between film and video? Is it the difference between 1CCD and 3CCD? Why would rental tapes not have this problem as they are converted to video? The shimmering really makes my digital video seem like much lower quality footage than what I am seeing on rental tapes. Any ideas? Here are some details of my experiments:

1. I am playing back from MiniDV tape in the camcorder to the TV or VCR via standard A/V in three plug cord that came with the camcorder. On my computer the original footage was transfered via a quality firewire cable and then played back via the hard drive. The cable from the VCR to the TV is a coaxial cable widely used for cable hookup, no transformer etc. I don't have an S-Video cable. And by the way, I hear that even S-video is not DV resolution, so how does one play DV resolution to any kind of monitor, TV, or HDTV?

2. I took my camcorder to a store that sells TVs and electronics. I hooked up my camcorder to a top of the line 27 inch TV directly with A/V in jacks. The quality of my video on this TV was way better than on my cheap TV at home but the halos and moving lines are still there, just much reduced.

3. I thought my computer with LCD screen would provide the highest quality output, but it doesn't. It has the worst haloes and moving lines of all. My LCD display has 50 ms refresh. One article mentioned that one needs a 20-30 ms refresh for proper video viewing. But my Dell Inspiron 8000 is specifically a multi media computer? Then there is the issue of interlaced video being shown on a non interlaced monitor? Hmm?

4. Hooking my computer to my 20 inch NEC tube type computer monitor results in better quality than my LCD screen. Why? But the NEC computer monitor wasn't nearly as clear as the 27 inch TV.

5. Initially I had low quality output on my TV with A/V jacks connected to the VCR. There were strips in the output with rental tapes too. I fixed this by changing to a new coaxial cable between the VCR and the TV. What a difference. Still I'm told that my TV and VCR are low quality and have limited resolution and can't handle the high resolution output of my camcorder. I'm still getting more shimmering haloes and lines than on the top of the line 27 inch TV at the store.

6. The sales person said hooking up to a proper video monitor would result in even better viewing quality. Where would I even find one of these to try my camcorder on? But who cares. I'm going to be viewing my footage on normal TVs.

[Jeff Donald]

How are you hooking up your camera to playback on the various devices you mention? What type of cables are you using, coaxial, S-Video, RCA type etc.?

[Ben Wiens]

Jeff, see my edited message above regarding hookup to TV or monitor.

[Jeff Donald]

Running the signal through the VCR or using the Coaxial connection (F connection to antenna) will result in a lower quality signal. Connect the device to the monitor directly using either the S-Video connection (highest quality) or the AV jacks (using a RCA connection, Lower quality). The coaxial connection (RF signal) will provide the lowest quality signal.

[Ben Wiens]

Jeff, my own nearly new TV does not have A/V in jacks so I connected the camcorder to my TV via the VCR. The VCR is connected to the TV via a coaxial cable. Are you saying this results in substantially inferior image than hooking up my camcorder directly to a TV with A/V input jacks? Do the A/V input jacks bypass the RF signal system on the TV?

Still why do the rental tapes not have the shimmering? They are being played back on my VCR which is connected to my TV via the coaxial cable in the same way.

[Jeff Donald]

Yes, using the RF connection is inferior to A/V jacks, the signal goes through at least two extra conversions and is more suspectable to RF interference. I can't answer what is causing the halo effects etc. because I can't see them. There is certainly a possibility that it is being caused by RF interference.

How was your camera hooked up to a TV at the store? A/V jacks or RF? Your computer monitors will not display interlaced signals properly. They do not use NTSC phosphors in most cases too. LCD displays have a significant delay as you've noticed. They to are not optimized for NTSC video.

My best guess is you are seeing several different anomalies with different causes. Single chip cameras will show more artifacts on sharp transitions than most 3 chip cameras. The rainbow effect could have several different causes, including the RF connection, camera design, subject and many more. I would start by getting the best possible signal into your display device. This means not using the RF connection, if possible.

[Ben Wiens]

Jeff, thanks for the information. Still I'm confused. Why do the rental tapes not have the shimmering? They are being played back on my VCR which is connected to my TV via the coaxial cable in the same way. Why can't I find anyone else that has seen this problem? It isn't just my camcorder, because my dad's has the very same problem. And my 82 year old mom with her poor eyesight (retinal damage at age 3) had seen the shimmering years ago on their camcorder before I even mentioned it.

[Glenn Chan]

If your TV can do this, turn the "sharpness" setting all the way down. Do the same on your camera if it has that setting (most consumer cams don't).

The halos are part of your footage as you record it. It might be some sort of analog problem (with the CCDs). Video has always had this problem. Film does not suffer from this problem.

Your second problem: shimmering of object edges. Maybe you are talking about moire effects? That kind of thing happens with ties with fine patterns and with fences and other kinds of fine detail. If you watch broadcast television you will probably run into it. It has something to do with how your TVs work. On a computer monitor you won't see this.

There's also stairstepping and false colors which are other video problems.

[Jeff Donald]

Without seeing images it's all just guess work at this point. Glenn has mentioned a few of the many possibilities. The moire patterns (usually) are caused by a crosstalk with the subcarrier frequencies. There are many factors than can contribute to the effect, but without images, it's all speculation.

[Ben Wiens]

Hi Jeff, it's hard to post video. But I thought if I was having this problem surely it must be a universal thing experienced by millions of others? Really has no one of the other million DV camcorders users ever seen this shimmering, moving moire, or whatever before? I thought someone would say. Oh, yeah, all video has this problem or something like that.

[Jeff Donald]

Send me a short Quicktime clip. Keep it under 8mb and I'll take a look.

[Ben Wiens]

Here is a 2 second AVI clip of my shimmering video. Any ideas would be appreciated. Note that the video was captured with a demo version of Ulead, through a firewire cable, to my firewire equipped notebook computer. As far as I can tell the AVI file uses only the same within frame compression as the original DV stored on the MiniDV tape of my Panasonic PV-DV852 camcorder.

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