Sanyo Z4 HDMI input - blank pixels at sides of image

Bert Coules

Well-known Member
If I feed my Sanyo Z4 with the HDMI signal from my Sky HD box, the image isn't full-width compared to the component input: there are two narrow vertical bands of unilluminated pixels (is that the correct term?) at the sides of the picture. The height, however, is full.

Though the difference is small, it's certainly noticeable: obviously it's most apparent on circles and the like, but everything is quite definitely squashed.

Is there anything I can do about this?

Many thanks,

Bert
www.bertcoules.co.uk
 

spooney

Well-known Member
Bert, this must be your Sky box. I never saw this with a DVD player or a PC via HDMI/DVI

You can try to change the overscan setting in the pj. This will crop pixels/lines.
 

Bert Coules

Well-known Member
Spooney, thanks. I'll experiment today to see if the DVD player's HDMI output gives the same result.

Is the Sky box HD output via component the same quality as the HDMI signal? That might be a solution, assuming that the component output doesn't do the same trick.

Bert
www.bertcoules.co.uk
 

Bert Coules

Well-known Member
Spooney,

I tried changing the overscan setting. Unfortunately, it adjusts both horizontal and vertical simultaneously, preserving the aspect ratio, so it's no good for what I need: I want to keep the vertical as it is and just change the horizontal.

Incidentally, at a very rough approximation, I'm getting blank bars of about 100 pixels at each side of the picture when I feed the Z4 with the HDMI output of my Sky HD box.

If anyone else has any ideas I'd be grateful.

Bert
www.bertcoules.co.uk
 

spooney

Well-known Member
Bert, I suggest to post a messsge with Sky Box and the problem description in the subject line and ask the question regarding component and HDMI again.
I know there are many people in these forums owning a Skybox.

Good luck
 

Bert Coules

Well-known Member
I've now tried the HDMI output from my Oppo DVD player into the Z4 and the effect is exactly the same: the HDMI image is narrower than the component one, although the vertical height remains constant. The squeezing effect is quite noticeable on some programme content. This means that the problem's not with the Sky HD box but with the projector.

This is real bind and I'm hoping that the Z4 is configurable in some way to eliminate it. Or could it be that my particular unit has a fault? I've seen no-one else mention this, not even in the rash of messages here when the Z4 was new.

Does Sanyo accept technical queries by email, I wonder?

Bert
www.bertcoules.co.uk
 

spooney

Well-known Member
Could it be the player gives different outputs? I remember a thread where somebody was complaining about something similar. In that case the person was used to a incorrect aspect ratio via component and did not want to accept the correct ratio via HDMI. He even attached pictures to demonstrate and the HDMI was correct.

With my Panny S52 and the Z4 I have no difference at all.
 

Bert Coules

Well-known Member
Thanks for the thought. The Oppo does have switchable output resolutions and I haven't tried checking different ones yet to see if it makes any odds. I could try switching the Sky box resolutions too, though it seems odd that the component outputs in each case should have perfect geometry while the HDMI signals do not.

I must try to find that earlier thread.

Bert
www.bertcoules.co.uk
 

Bert Coules

Well-known Member
Switching to different output resolutions (both on the DVD player and the Sky HD box) makes no difference: the problem is still there.

I emailed Sanyo UK customer services asking if there was an adjustment for the horizontal image size. This was the reply:

No there is no adjustment; this is the way in which the internal Scalar
is managing the HDMI(High Definition Multi-Media Input) signal.

In some cases the external HDMI equipment attached to the projector has
various Picture fit options in the menus, I would therefore suggest
checking The menus out on your external HDMI equipment.


I think they misunderstood the problem: I was talking about a small (yet obvious) distortion, but their reply surely refers to the standard gross adjustments (zoom, wide, normal, etc).

I'm truly surprised that no-one else seems to be suffering from this effect.

Bert
www.bertcoules.co.uk
 

spooney

Well-known Member
Bert, I just switched to a DENON 2930 for my Z4 and there is no problem at all (and the picture looks a million times better).
 

Bert Coules

Well-known Member
Bert, I just switched to a DENON 2930 for my Z4 and there is no problem at all (and the picture looks a million times better).
A million times better than the Oppo? That must be impressive indeed.

On the question of the picture geometry let's see if this will work:

This is the output from the Oppo via component:

Component.jpg


And this is HDMI:
HDMI.jpg


Even allowing for the slight distortion introduced by the camera and the fact that the overall projected amount of the image is not quite the same, I hope you can see that the geometry of the HDMI image is definitely different from the component one: the central circle is distinctly squeezed horizontally - though curiously, the frame-edges of that test pattern seem almost perfectly evenly displayed. So what can be going on?

Edited to add:

Courtesy of a friend, here are the two images superimposed:

Superimposed.jpg


The difference is really clear.


Bert
www.bertcoules.co.uk
 

spooney

Well-known Member
Bert, now am completely confused and lacking any explanation.
The HDMI picture shows significant more content opposite component.
Somewhere in the chain the pciture must be corpped. Very strange :confused:
 

Bert Coules

Well-known Member
The HDMI picture shows significant more content opposite component.
Yes, it's odd isn't it. I tried to adjust one or other or both projected pictures to get the coverage the same, but I couldn't: the component overscan adjustment is already at zero, and there's no overscan setting available for HDMI.

I think I'll send those jpgs to Sanyo to see what they say.

Bert
www.bertcoules.co.uk
 

bravogolf

Active Member
Hey Bert, I can't offer anything constructive am afraid. I checked my DVD player (see sig, can't remember the model number) via Component and HDMI and noticed no cropping, so that might rule out a known issue with all models.

What DVD are you using in that pic?
 

Bert Coules

Well-known Member
Bravogolf, thanks for the reply. It's not just the DVD player: I get exactly the same effect from the HDMI and component outputs of my Sky HD box - it's most obvious on circles of course (like the new BBC1 logos) but it can be seen on all material.

The geometry pattern I used for the pics is from the Digital Video Essentials DVD.

Bert
www.bertcoules.co.uk
 

Bert Coules

Well-known Member
Something I hadn't noticed before: the HDMI picture is further out of register with the component image at the edges than in the centre: so the distortion isn't even regular.

It's like a more subtle version of those settings which stretch a 4x3 picture to fit a 16x9 screen by progressively expanding the image the nearer to the sides you get.

Bert
www.bertcoules.co.uk
 

canlabmaster

Active Member
Having read this thread with interest, I can say that I have noticed a similar effect with my Z3 projector used with an Oppo. With HDMI, the image is smaller, not just horizontally, but vertically too (in scale) compared with component feed. I would suspect there is a tweak or two (or three) in the service menu to correct preset geometries for analogue inputs but I wouldn't have a clue how to go about it.

Your more recent discovery about a lack of linearity in the horizontal image might be expected given that the projector is converting analogue signals to digital in order to display them and some slight non-linearity may be unavoidable (analogue CRT TV displays suffer this way don't they?). With digital into the projector via HDMI, geometric distortions should be pretty much zero though, so your HDMI input should be your reference.
 

Bert Coules

Well-known Member
Having read this thread with interest, I can say that I have noticed a similar effect with my Z3 projector used with an Oppo.
Thanks for that. I was beginning to think that no other Sanyo owner had ever experienced the problem.

I would suspect there is a tweak or two (or three) in the service menu to correct preset geometries for analogue inputs...
I agree, and if I could find the details I'd try a mild tweak or two - after all, I could always reset things if the result didn't turn out well.

...so your HDMI input should be your reference.
Except for the small (or not so small) detail that it's the HDMI image which is distorted - the picture via component has the geometry (at least of that centre circle) spot-on.

Bert
www.bertcoules.co.uk
 

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