Hi all

I'm trying to understand why the PAL Wii causes so many problems with certain HDTVs when using playing VC Megadrive, SNES or NES games over component connections. Many lose sync or start drawing garbage.

These games always output at 576i no matter what the Wii is set to.

On my vp50, if I have it set to 50Hz Lock output, then I get the loss of sync on my plasma.

However, if I set it to Unlocked (50.00Hz) then it's fine.

What is the difference between these two modes? The manual says something like, "Locked guarantees one and only one output frame for each input frame"

Does this mean the Wii is failing to produce a consistent 50Hz framerate and when Locked, the VP is passing that problem onto my TV? Whereas if it's unlocked then the vp50 always generates a frame every 50th, and it re-sends the last frame if there isn't a new one from the source?

or something completely different?

Really want to figure out what's going on here in order to get Nintendo to do something about it.

Stoomonster has already emailed dvdo to see if we can get some sort of diagnostic info about the signal it's receiving.

Check out this thread (http://www.avsforum.com/avs-vb/showthread.php?p=6985487&highlight=unlocked#post6985487) , Dale has a nice explanation of the differences. It's directed at the VP30, but I think the content ragarding framerates would still apply to the VP50. Being a noob I still don't understand all of it :o

What is the difference between these two modes?
From the FAQ on the DVDO website:

"Locked mode (1:1). This means that the iScan's output frame rate tracks the input rate - i.e., the output rate is locked to the input rate. In the 1:1 mode - i.e., 60 Hz source-locked to 60 Hz, and 50 Hz source-locked to 50 Hz - there is always exactly one output frame for every input frame/field. This mode has the advantage that there are never any dropped or repeated frames (unless the source itself does this). One disadvantage of this mode is that when the video source is changed, the iScan has to re-lock to the new input signal timing. This causes a disruption in the iScan's output signal while the locking process occurs, and can cause many displays to loose sync to the iScan's signal and temporarily blank.

Unlocked mode. This means that the iScan's output frame rate is independent of the input rate. Regardless of any variations in the input, the output frame rate will be fixed at the specified value. This mode results in the most stable output signal as it's independent of any changes in the input signal. Unlike the locked mode(s), the iScan's output signal timing will not be disrupted when the input source is changed. However, it's guaranteed to cause dropped or repeated frames as the input and output frame rates are not the same. Note that regardless of what number the unlocked output frame rate is set to, it will never be identical to the input rate in this mode as the output signal timing is independent of the input timing. These dropped/repeated frames can result in visible irregularities in smooth motion, sometimes called motion judder or stutter."


One other disadvantage of the locked mode that is not mentioned in the FAQ is that if there is instability in the input signal, then some manifestation of that instability will be present in the output. In cases where the input signal timing to the VP50 varies significantly, it can cause the number of lines in an output frame to vary. This will cause many displays to re-synch to the signal as they think that the signal format has changed. I don't believe I've seen this sort of behavior on anything other than some VCRs in 'trick play' modes (i.e., fast forward/reverse or pause), but perhaps the signal from the Wii is unstable enough to cause this. You might see this if the frame period from the Wii is not constant and varies from frame to frame.

There is no such variation in the unlocked mode. The output timing in this mode is rock solid regardless of the input timing. The disadvantage is that you can get dropped or repeated frames, but in this case it may be much better than no picture at all.

I don't know any good way of verifying this without some test equipment. It's fairly easy to do with a decent digital oscilloscope - just look at the sync signal timings from the input signal and see if they're constant or not. You can also look at the vertical sync signal of the VP50's output and see if that's varying by a scanline from frame to frame, as that's a sure sign that the input signal is unstable.

- Dale Adams

Thanks guys. I'm pretty sure the UK gave up on real work so long ago that we don't have oscilloscopes in the country any more but I'll see if I can lay my hands on one :)