CurtPalme.com Home Theater Forum

[Baard]

I’m stuck in “ in-compatibility” problems with SD-DVD and Moome ETX-HD. Until Easter I have used HTPC with no problems, switch too more family friendly setup with Toshiba XE1 and Moome ETX-HD too Barco. Mostly due too SD-DVD scaling in XE1 vs HTPC is good enough.

Internal scaling in XE1 on SD material through Moome EXT-HD is a problem. 720-1080i/p@50Hz – is obviously not a CRT friendly setup, with great reduction in picture wide. Front/back porch settings?

Picture on BG 1208s is a bit too soft at 1080p – as expected though. I only use 720p or 1080i on HD, I achieve great picture size at 1080i, but I am a bit bothered with scanned lines in this mode. 720p gives also reduced picture size vs HTPC. Contrast ratio is better in p vs i mode – much more light.

As is: I am not happy with Moome and XE1 on SD-DVD. This was note as excepted – maybe I should see this coming?


Baard

[kal]

Sorry, I don't understand what the problem is that you are having. You mention that 720p/50 and 1080i/50 and 1080i/50 are too narrow. That has nothing to do with the EXT-HD - the EXT-HD simply passes through the information from the source. It doesn't change the porches at all.

I used an EXT-HD at all those resolutions (60Hz though) and th EXT-HD looked fantastic and did exactly what I expected.

Kal

[kal]

Sorry, I don't understand what the problem is that you are having. You mention that 720p/50 and 1080i/50 and 1080i/50 are too narrow. That has nothing to do with the EXT-HD - the EXT-HD simply passes through the information from the source. It doesn't change the porches at all.

I used an EXT-HD at all those resolutions (60Hz though) and th EXT-HD looked fantastic and did exactly what I expected.

Kal

[drudozucker]

[Baard]

Sorry – I will do my best to rephrase. (Different language and uncertain technical skills)

- it’s not about picture quality
- Problem is picture size on SD-DVD at 50Hz from Toshiba XE1 through EXT-HD.

Playing SD from Toshiba – up scaled to 720/1080p @50Hz the resulting picture is squeezed together, just like 4:3. (Format settings in Toshiba is 16:9)

HD-DVD@60Hz is very nice.

I thought is was a timing issue in EXT-HD @50Hz in combination with CRT.
A work around for SD-DVD is connecting HTPC 1280:720p@60Hz through DVI/HDMI too EXT-HD. And everything is fine.

But I want to simply my setup and do SD scaling through Toshiba HD player – this doesn’t turned out as expected due to 50Hz issue??

Summing up
Still have to use HTPC for SD in combination with Blu-ray/HD-DVD player.
It should have been 3 HDMI ports on EXT-HD, well well….

Baard

[Baard]

[WTS]

Edge enhancement? You've got to be joking, who would artificial edge enhancement, not on my cine.

[kal]

Udo/Baard: This is good feedback. I'll make sure that Moome gets it.

[kal]

Udo/Baard: This is good feedback. I'll make sure that Moome gets it.

[drudozucker]

[kal]

[kal]

[drudozucker]

Hi Kal, you might have misinterpreted my statement. My example of the digital SLR wasn't to reason edge enhancement for HD but to simply explain how "intelligent" sharping can make things better. I also do not believe that the EXT-HD (at his price) could include a good (and user selectable!) edge enhancement, so I would not advocate for it, but consider it a great opportunity for a product at a higher price. I am a "fan" of the EXT-HD and believe, that it is a great product (as soon as it is fixed for 50Hz). Reason to explain the obsrvation about the "missing" edge enhancement was purely done to explain why a picture could look soft when compared with a dedicated scaler or HTPC.

Having said this, you might imply that the output of the EXT-HD is what is captured on the HD disk. This is unfortunately not true. Take a test pattern which raises from IRE 0 to IRE 100 (as fast as possible within the bandwidth limitations of the recording). Then look at the analog video signal and you can see that it has, after a fast raise time, round shoulders because of the bandwidth limitations or maybe simply the necessary (anti-aliasing) filtering. Using "intelligent" edge enhancement could make this better, but if "cheaply" done would results in ringing.

Regards
Udo

[kal]

Ok, understood Udo. I agree that most sharpening is done poorly. There's a reason why good sharpening is very hard to do (very computing intensive).

Kal

[kal]

Ok, understood Udo. I agree that most sharpening is done poorly. There's a reason why good sharpening is very hard to do (very computing intensive).

Kal

[WTS]

udo, have you tested the ext hd with such a test pattern and found the analog output to have rounding or slewing? The opamps in the lastest versions have a very high BW and slewrate where I don't see this as being a problem.

[drudozucker]

[WTS]

Hi Udo,

I'm not familiar with the Tag unit you are using, could you give some info on it? What EXT unit do you have?

Interesting scope shots. I would alomost bet that the video dac in the ext has no post filters which would probably explain the ripples that you see on the waveform. Interesting enough the manufacturer of the HDMI chip which also includes the dacs internally (if you have the unit I think you do) only recommends a ferrite bead/cap for a post filter. Hardly the 5th order butterworth filters the Tag uses, does it make a huge difference, I don't know, I know Tag equipment is very expensive.

It appears that the rise times of both signals initially the same but when they reach the top it almost seem like the EXT signal is either BW limited or the Tag is slightly peaked in the BW to get that overshoot. Again the rippling seen on the EXT waveform is probably the result of no post filter.

The 2 signals in the 3rd picture look similiar from what I can tell with the exception that the EXT waveform again has the unfiltered look to it. Don't forget that while filters do clean up the sampling artifacts like the ripples they also tend to soften the waveform (picture). What is the bottom trace in the 3rd picture?

Perhaps you should take your blackbox configuration a step futher and open it up and scope the dac output right at the 75ohm load before it goes through the other stages because the other stages include more than just a buffer. I'd like to see what the results show for that, you could also add a ferrite bead and a small cap (10pF, 27pF etc) and see what it does for the ripple.

Interesting artifact(2nd peak) in the second picture. Where's the picture of the Tag output for this input?

Newer units from Moome are using separate HDMI - dac chips and also a higher spec video buffer.

Walter

[drudozucker]

Hi Walter, I have an EXT-HD from the most recent batch, i.e. March 2008.

The video output of the TAG McLaren VSM2048 has been processed by a PW181-30, which also offers the edge enhancement option. I do not believe there is a bandwidth issue within the EXT-HD which I believe is verified by the 1 pixel wide test pattern [picture_2].

The ripples are, as you say, and as I think, caused be an insufficiently processed (not edge enhanced!) analog video output.

I could not produce picture_2 with the TAG McLaren VSM2048 as it cannot store 1920x1080p, it downsizes the input to approx. 1300x1080p. As a result the one pixel wide peaks are not reproduced with identical width; they vary by a small fraction. Not an issue as such but because I do not have access to an storage oscilloscope, I cannot make a steady screen shot. As soon as I have some time, I will try one using 1920x1080i as that can be processed and as the peaks are one pixel wide, it shouldn't matter, if I use 1080i or 1080p.

Picture_3 has been recored at 50ns/div.

I did open the EXT-HD but as I do not have a circuit diagram and important ICs having their product number removed, I did go further. I do not have the time to reverse engineer the EXT-HD. If you have additional details, then please share them with me. I would be most interested to learn more about the EXT-HD. Having said this, I might in the future add a filter, as used inside the TAG McLaren, to the output of the EXT-HD. However, I will only start this after the 50Hz issue is resolved (as that is necessary to make proper use of the EXT-HD in Europe).

Regards
Udo

[WTS]

Hi Udo,

The video outputs of the HDMI chip come out the left side of the chip(don't recall the pin #s) and double terminated into 2 75R, one at the output here the HDMI and one at the input of the buffer. It's not that difficlut to see this on the circuit board, there's no need for reverse eng.

[VideoGrabber]

WTS commented:
> Again the rippling seen on the EXT waveform is probably the result of no post filter. <

That must be it, Walter, since the ripple frequency seen in the scope pix is at 149 MHz (4x 37.25 MHz), and is only ~40 dB down. At that point, spurious products should be at least 60 dB down, but you don't get that without any filtering.

[VideoGrabber]

Udo,
really nice job on the edge enhancement graph.

If the EXT-HD were properly filtered, its output would closely approximate the Min filter setting, but with 0 enhancement. It would be hard to fault the Min filter setting from the TAG McLaren, unless the source material already had EE applied, which would then be amplified even further. On a big screen, problems like these become painfully obvious.

Completely clean source material may benefit from the Mid setting, but the Max setting would be significantly worse in most all cases. Note it exhibits both undershoot and overshoot, which result in both light and dark outlining of ~15 nS (several pixels wide @1080p) around object edges.

[drudozucker]

[WTS]

It would be interesting to see a scope shot of the ext with the rcommended filter and see if it makes an improvement.