T2 - blurry picture at 576i/p

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T2 - blurry picture at 576i/p

Post by sonicblue » Tue Oct 31, 2017 12:16

Problem description

Image resolution appears to be lost in the horizontal direction when outputting 576i/p over HDMI

Image

(Open image in new tab to view full size)


Reproducing the issue

Download the test pattern video in 576i or 576p format and play through the T2's media player with the T2's HDMI output mode set to 576i or 576p. For completeness here are 1080i and 1080p versions of the pattern.


Additional notes

720p and 1080i/p modes appear to be unaffected.

On German forums it was reported that "/proc/stb/vmpeg/0/pep_scaler_sharpness" set to a value of 13-18 solved the issue for them. However this setting is not exposed on the T2 and would seem to require a driver update to support it.

Other unsupported scaler settings which may be related to this issue

/proc/stb/vmpeg/0/pep_scaler_vertical_dejagging
/proc/stb/vmpeg/0/smooth


Proposed Solution

Driver update to support "pep_scaler_sharpness" with user control from Settings - Video Enhancements section.
Last edited by sonicblue on Wed Apr 15, 2020 17:42, edited 11 times in total.

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Re: T2 - blurry picture at 576i/p

Post by prl » Tue Oct 31, 2017 12:31

I'm not sure why you're giving a "pass" to the top right quadrant in 576p. Its aliasing seems pretty bad, or is that aliasing/moiré from the camera (it doesn't look like moiré from the camera, though)?
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Re: T2 - blurry picture at 576i/p

Post by sonicblue » Tue Oct 31, 2017 12:52

prl wrote:
Tue Oct 31, 2017 12:31
I'm not sure why you're giving a "pass" to the top right quadrant in 576p.

Apparently it still counts as resolution if we can count all the lines and the interline contrast is greater than 30%, which technically it is (need to open the image in a new tab and zoom to 100%). From a videophile perspective I agree it should be a fail if its even slightly softened :D
Last edited by sonicblue on Tue Nov 07, 2017 23:09, edited 1 time in total.

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Re: T2 - blurry picture at 576i/p

Post by peteru » Tue Oct 31, 2017 14:13

I'd be very, very surprised if there were any driver enhancements for the T2, T3, or T4 in the future. Even if it was technically possible, you are talking about spending thousands or even tens of thousands of dollars on enhancing end-of-life products. The drivers are not Open Source and developers need to get paid. Not only that, you would need updated SDKs from Broadcom, but that's not possible because Broadcom have archived these products.

I suspect that the U4 will be the next focal point for development.

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Re: T2 - blurry picture at 576i/p

Post by prl » Tue Oct 31, 2017 15:39

peteru wrote:
Tue Oct 31, 2017 14:13
...
I suspect that the U4 will be the next focal point for development.
The U4 has /proc/stb/vmpeg/0/pep_scaler_sharpness, and it can be controlled by MENU>Setup>Video enhancement>Sharpness.

It doesn't have either of the other /proc/stb/vmpeg files mentioned in sonicblue's post.

Code: Select all

root@beyonwizu4:~# ls /proc/stb/vmpeg/0
alpha                         fallback_framerate_choices    pep_hue
aspect                        framerate                     pep_mosquito_noise_reduction
clip_apply                    pep_apply                     pep_saturation
clip_height                   pep_auto_flesh                pep_scaler_sharpness
clip_left                     pep_block_noise_reduction     pep_sharpness
clip_top                      pep_blue_boost                pep_split
clip_width                    pep_brightness                progressive
dst_apply                     pep_contrast                  progressive_override
dst_height                    pep_deinterlacer_sharpness    progressive_override_choices
dst_left                      pep_digital_contour_removal   xres
dst_top                       pep_dynamic_contrast          yres
dst_width                     pep_green_boost
fallback_framerate            pep_hscaler_sharpness
root@beyonwizu4:~#
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Re: T2 - blurry picture at 576i/p

Post by sonicblue » Tue Oct 31, 2017 17:07

peteru wrote:
Tue Oct 31, 2017 14:13
Even if it was technically possible, you are talking about spending thousands or even tens of thousands of dollars on enhancing end-of-life products.

There appears to be an open source enigma2 software called OpenPLi which seems to support it. Is it possible that OpenPLi code could be integrated somehow?

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Re: T2 - blurry picture at 576i/p

Post by prl » Tue Oct 31, 2017 17:13

The Beyonwiz variant of the enigma2 firmware supports it, too, provided the underlying device drivers do, as can be seen from the fact that it can be modified on the U2, running exactly the same source code of VideoEnhancement.py as the T2 (and T3 and T4).

OpenPLI is simply another variant of the enigma2 firmware.
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Re: T2 - blurry picture at 576i/p

Post by IanSav » Tue Oct 31, 2017 17:17

Hi Sonicblue,
sonicblue wrote:
Tue Oct 31, 2017 17:07
There appears to be an open source enigma2 software called OpenPLi which seems to support it. Is it possible that OpenPLi code could be integrated somehow?
OpenViX and OpenPLi do work together and share some code. Beyonwiz draws most of its upstream code from OpenViX.

If you accurately point out and list the specific commits and/or source code you want integrated into the Beyonwiz build here PeterU may consider your request.

Regards,
Ian.

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Re: T2 - blurry picture at 576i/p

Post by prl » Tue Oct 31, 2017 17:35

The code that allows you to change /proc/stb/vmpeg/0/pep_scaler_sharpness is already in the Beyonwiz code. It works on the U4 and makes the "Sharpness" slicer available in MENU>Setup>Video enhancement.

It works on the U4 and not on the T{2,3,4} because the U4 has a /proc/stb/vmpeg/0/pep_scaler_sharpness file and the others do not.

The /proc/stb/vmpeg/0/pep_scaler_sharpness file is created by the device drivers in the kernel.

The Beyonwiz, OpenPLi and OpenViX code repositories do not contain the device driver source code. Peteru has said that the device drivers are proprietary software supplied only by Broadcomm.

The only difference between the VideoEnhancement plugin in the Beyonwiz source and the same plugin in OpenViX is:

Code: Select all

--- [OpenVix]/lib/python/VideoEnhancement/plugin.py     2017-08-26 12:32:43.000000000 +1000
+++ [Beyonwiz]/lib/python/Plugins/SystemPlugins/VideoEnhancement/plugin.py    2017-07-07 17:25:27.000000000 +1000
@@ -23,7 +23,7 @@
                self["HelpWindow"].hide()
                self["VKeyIcon"] = Boolean(False)
                self['footnote'] = Label()
-               self["description"] = Label(_(""))
+               self["description"] = Label("")
 
                self.list = [ ]
                self.xtdlist = [ ]
That difference is irrelevant to the Sharpness slider and is in fact correct in the Beyonwiz code and incorrect in the OpenViX code (but the error is probably not apparent to users).
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Re: T2 - blurry picture at 576i/p

Post by sonicblue » Tue Oct 31, 2017 18:14

Is this repository of any use, specifically here and here which seem to include some driver files for the BCM7362.

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Re: T2 - blurry picture at 576i/p

Post by prl » Tue Oct 31, 2017 18:47

sonicblue wrote:
Tue Oct 31, 2017 18:14
Is this repository of any use, specifically here and here which seem to include some driver files for the BCM7362.

Can you be more specific as to which files might be relevant? I can't see anything in the two linked directories that sticks out as related to the BCM7362's DVB capabilities.
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Re: T2 - blurry picture at 576i/p

Post by sonicblue » Tue Oct 31, 2017 20:19

prl wrote:
Tue Oct 31, 2017 18:47
Can you be more specific as to which files might be relevant? I can't see anything in the two linked directories that sticks out as related to the BCM7362's DVB capabilities.

Sorry I don't know how to program linux drivers and therefore have no idea about the content of the driver source files :oops:

I will try to search through them for keywords though :)

In the meantime if anyone with a U4 could report whether the test pattern is good , it would be much appreciated.

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Re: T2 - blurry picture at 576i/p

Post by prl » Tue Oct 31, 2017 21:58

sonicblue wrote:
Tue Oct 31, 2017 20:19
prl wrote:
Tue Oct 31, 2017 18:47
Can you be more specific as to which files might be relevant? I can't see anything in the two linked directories that sticks out as related to the BCM7362's DVB capabilities.

Sorry I don't know how to program linux drivers and therefore have no idea about the content of the driver source files :oops:

I will try to search through them for keywords though :)
...

It looks to me like Linux source to run on the BCM7362 (and possibly other similar Broadcomm SOCs), but without the source code of the bits that Broadcomm wants to hold proprietary.
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Re: T2 - blurry picture at 576i/p

Post by sonicblue » Wed Nov 01, 2017 07:22

If we knew the exact names of the driver files, then it should be easy to search the repository for those files.

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Re: T2 - blurry picture at 576i/p

Post by prl » Wed Nov 01, 2017 07:48

sonicblue wrote:
Wed Nov 01, 2017 07:22
If we knew the exact names of the driver files, then it should be easy to search the repository for those files.

Yes, but I don't think that they are there at all.
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Re: T2 - blurry picture at 576i/p

Post by sonicblue » Wed Nov 01, 2017 07:58

Ok, thanks to everyone who commented.

I will continue to check this thread and if it becomes clear in the next 2 weeks that the issue definitely cannot be solved with a firmware update then I will probably look into replacing it with a U4, as I like the general feature set of the T2. Am I correct in assuming the U4 won't lack any features of the T2? i.e it will run the same plugins like EPG refresh, allow the same advanced customisation of the EPG views, all the same auto resolution options, media player features etc. The user manual seems to imply so.

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Re: T2 - blurry picture at 576i/p

Post by peteru » Wed Nov 01, 2017 08:11

peteru wrote:
Tue Oct 31, 2017 14:13
The drivers are not Open Source

You won't find anything useful on Github or anywhere else. You can't use drivers from other devices either, because there are differences between board designs. If you try to use the driver for the wrong board, you run a good chance of frying something on the board.

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Re: T2 - blurry picture at 576i/p

Post by prl » Wed Nov 01, 2017 11:05

sonicblue wrote:
Tue Oct 31, 2017 20:19
...
In the meantime if anyone with a U4 could report whether the test pattern is good , it would be much appreciated.
On the U4, the results for the posted test file both 576i and 576p outputs look pretty much the same as each other. The fine vertical lines (upper left quadrant) are smeared to an almost uniform grey. Fairly strong aliasing on the wide vertical lines (bottom left quadrant) and on the fine horizontal lines (top right quadrant).

Changing /proc/stb/vmpeg/0/pep_scaler_sharpness to 00000013 (or anything else I tried) didn't appear to make any appreciable difference. It didn't matter whether I changed the /proc file through the GUI or via the command line.
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Re: T2 - blurry picture at 576i/p

Post by sonicblue » Wed Nov 01, 2017 11:58

prl wrote:
Wed Nov 01, 2017 11:05
sonicblue wrote:
Tue Oct 31, 2017 20:19
...
In the meantime if anyone with a U4 could report whether the test pattern is good , it would be much appreciated.
On the U4, the results for the posted test file both 576i and 576p outputs look pretty much the same as each other. The fine vertical lines (upper left quadrant) are smeared to an almost uniform grey. Fairly strong aliasing on the wide vertical lines (bottom left quadrant) and on the fine horizontal lines (top right quadrant).

Changing /proc/stb/vmpeg/0/pep_scaler_sharpness to 00000013 (or anything else I tried) didn't appear to make any appreciable difference. It didn't matter whether I changed the /proc file through the GUI or via the command line.

Thanks for testing that.

There is one alternate possibility - your TV's scaler could be applying its own filtering as well. I have noticed this on some displays, including Samsung plasma, Panasonic plasma and Kogan LCD's. A 2014 LG OLED was found to be filtering out details as well [1]. Anecdotally some of the earlier model Pioneer plasmas were guilty of it too. My parents currently use a Panasonic plasma which fails 576i HDMI but passes 576i over analogue component. I did check the T2's analogue component output and found it was the same as well, and also checked the test pattern is passing when sent from another device (Sony DVD player displaying SMPTE resolution pattern 133).

Mysterious...
Last edited by sonicblue on Fri Nov 03, 2017 10:09, edited 1 time in total.

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Re: T2 - blurry picture at 576i/p

Post by prl » Wed Nov 01, 2017 12:15

sonicblue wrote:
Wed Nov 01, 2017 11:58
... There is one alternate possibility - your TV's scaler could be applying its own filtering as well. ...

That's entirely possible. As I said earlier my setup (even our loungeroom setup) is decidedly low-end.

I did the tests on the Digitel ETI16SA6DA in the test setup on my desk (yes, my desk is very crowded).

Turning off the Digitel's noise reduction and changing its sharpness setting had no useful effect on the result.
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Re: T2 - blurry picture at 576i/p

Post by sonicblue » Fri Nov 03, 2017 09:59

Are there any other testers out there with a U4 and a TV that can resolve 576i/p who could please check the test pattern and report whether it passes. I need to find out preferably in the next 7 days so I can plan what to do with the T2, whether to keep it or ask Beyonwiz for store credit towards a U4. I figure the longer I leave it the less my chances are at the latter :lol:

Thanks!

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Re: T2 - blurry picture at 576i/p

Post by prl » Fri Nov 03, 2017 10:07

sonicblue wrote:
Fri Nov 03, 2017 09:59
Are there any other testers out there with a U4 ...

That's peteru and Jai (Wiz HQ). I've already reported back on it. My understanding is that a another U4 is under way to another tester, but I don't think he's received it yet.
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Re: T2 - blurry picture at 576i/p

Post by MrQuade » Fri Nov 03, 2017 11:13

Despite not having a U4, I just want to make a note about this.
I took delivery of my a LG OLED TV last night and finally had time to set it up.

With the T4 set to 1080p output, that test pattern looks absolutely perfect on this TV. My previous Samsung D8000 TV was a little bit grey and muddy when displaying the pattern in the upper left quadrant.

The 576i output was a pass on all but the upper left quadrant, which only showed as a mass of grey.

Both the T4 and T2 showed similar results.
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Re: T2 - blurry picture at 576i/p

Post by sonicblue » Fri Nov 03, 2017 13:27

MrQuade wrote:
Fri Nov 03, 2017 11:13
The 576i output was a pass on all but the upper left quadrant, which only showed as a mass of grey.
Both the T4 and T2 showed similar results.

Your findings regarding the top right quadrant were different to mine, therefore I went back and rechecked everything, this time using my desktop PC as the source. Flipping back and forth between 576i/p from the Nvidia control panel with the test pattern open, I can confirm your findings are correct, and that it is my TV's scaler which is causing the top right quadrant to fail in the 576i mode.

i.e T2/T4 appears to be passing all resolution tests in the vertical direction. The only thing T2/T4 appears to be failing is the horizontal resolution in 576i/p output modes.

I will amend the original post to reflect this.

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Re: T2 - blurry picture at 576i/p

Post by peteru » Fri Nov 03, 2017 14:06

AFAIK both T2 and T4 use the same underlying hardware IP block for image processing. There is a difference in the Broadcom SDK version, however I do not think it would have a large impact.

The horizontal scaler hardware has several modes, including a programmable 8-tap FIR filter. These settings are at a very low level that is not readily accessible by people outside of Broadcom. The higher level APIs in the SDK used by device manufacturers are designed to do the right things out of the box. As long as you are not causing the image to be scaled horizontally, it should be pixel perfect. If you are seeing horizontal filtering, I'd suggest doing a full resolution screen grab of just the video from OpenWebif. This reads out the data from the frame buffer, just before it is clocked out to the HDMI bitstream and DACs. If the screenshot is blurry, then there has been some image processing applied on the T2. My guess would be that it's going to be just fine and that your image degradation is occurring further down the stream.

As far as U4 is concerned, I don't have enough detailed information to be 100% sure, but I believe that the hardware IP block for image processing is essentially the same as in the T4, but beefed up in terms of precision and bandwidth to deal with HDR images at 4k resolution.

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Re: T2 - blurry picture at 576i/p

Post by prl » Fri Nov 03, 2017 14:52

Here are video-only screengrabs using OpenWebif as suggested by peteru of the resolution test from the T2 -
at output resolution 576i:
restest-t2-576i.jpg
at output resolution 576p:
restest-t2-576p.jpg
And from the U4 -
at output resolution 576i:
restest-u4-576i.jpg
at output resolution 576p:
restest-u4-576p.jpg
The top right block on the U4 is a bit weird - for both 576i and 576p it alternates randomly between solid black and solid white on successive refreshes. On the TV, the block shows as striped on the screen in both modes, though heavily aliased.
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Re: T2 - blurry picture at 576i/p

Post by MrQuade » Fri Nov 03, 2017 15:24

Wow, the U4 is significantly softer!
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Re: T2 - blurry picture at 576i/p

Post by sonicblue » Fri Nov 03, 2017 15:34

I get the same result as prl on my T2. It appears the Webif screen grab is occurring before the scaler gets its hands on it though, as the captured image is 720x576 while the T2 is simultaneously outputting 1920x1080. Also the video enhancements controls don't affect the screen grab.

The U4 seems to be a different story as the solid black/white would seem to indicate bob deinterlacing took place before capture (edit: and the fact the screen grabs are 1920x1080 would seem to indicate the grabs are occurring after upscaling.) . The fact that prl is not seeing flashing black/white on the actual display seems to indicate the screen grabs aren't actually indicative of what's coming out of the HDMI port.
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Re: T2 - blurry picture at 576i/p

Post by peteru » Fri Nov 03, 2017 15:41

Apples and oranges. T2 shots are PAL resolution, U4 shots are FullHD resolution.

It's conceivable that the screenshot feature may be grabbing fields, rather than frames, in which case the temporal processing comes into play as well.

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Re: T2 - blurry picture at 576i/p

Post by peteru » Sat Nov 04, 2017 00:59

So what exactly are we testing here?

If the output is set to 576i and you feed it a test pattern that is encoded as 720x576i, you ought to be getting pixel for pixel output. In order to resolve that, you will need to capture both odd and even fields of the signal. If you set the output to 576p, then you should be able to capture the full frame and get both fields shown. Any deinterlacing algorithms are likely to interfere. As will a horizontal rescale, which can be triggered by all sorts of things, including an overscan/underscan setting.

Testing 1920x1080 output (interlaced or progressive) with 720x576i test pattern will engage the scalers, so you can't expect pixel accurate output.

In summary, I'm not sure as to what paths you are testing or what your expectations are. It may help to enumerate the scenarios that are under investigation.

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Re: T2 - blurry picture at 576i/p

Post by prl » Sat Nov 04, 2017 08:07

I've been testing the 576i resolution test file with 576i and 576p output set on the Beyonwizes. That's what I understood sonicblue was testing.
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Re: T2 - blurry picture at 576i/p

Post by IanB » Sat Nov 04, 2017 08:21

Another chink in this is the Nyquist requirements for dealing with only correctly band limited signal.

The given sample clip has artificial square wave elements which will have aliasing of the high frequency components when up-scaled with any truncated sinc filter to less than twice the original size, i.e. 1440x1152. So yes 1920 is greater than 1440 but 1080 is less than 1152.

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Re: T2 - blurry picture at 576i/p

Post by sonicblue » Sat Nov 04, 2017 10:04

Fair enough about 576i - it's going to be an unknown factor whether the TV's processor will use weave. I've not seen a Sony/Panasonic/Samsung/LG TV made in the last 10 years which used purely bob deinterlacing though. imo it's more likely to be other noise reduction filters that will cause a false negative.

For 576p - I mentioned earlier a 30% interline contrast as the passing factor. i.e the pixels dont have to map 1:1 or anything like that (as IanB has mentioned, it's impossible that they even could) but the lines should at least be countable with at least 30% contrast difference between them. Again this is going to depend on what scaling mode and filters your TV uses, and will result in a false negative on some displays. The only way to be sure is to capture the T2's HDMI output with a capture card and inspect the pixel values in software like Photoshop etc. I am willing to do this at my own expense if WizHQ could loan me a U4.

So it's 2017 and we're discussing whether our 4k TVs should be able to resolve standard definition :lol:

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Re: T2 - blurry picture at 576i/p

Post by sonicblue » Sun Nov 05, 2017 10:08

prl wrote:
Wed Nov 01, 2017 11:05
Changing /proc/stb/vmpeg/0/pep_scaler_sharpness to 00000013 (or anything else I tried) didn't appear to make any appreciable difference. It didn't matter whether I changed the /proc file through the GUI or via the command line.

By any chance did you happen to try the "pep_hscaler_sharpness" setting? Maybe the h stands for the horizontal scaler setting?

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Re: T2 - blurry picture at 576i/p

Post by prl » Sun Nov 05, 2017 13:26

sonicblue wrote:
Sun Nov 05, 2017 10:08
prl wrote:
Wed Nov 01, 2017 11:05
Changing /proc/stb/vmpeg/0/pep_scaler_sharpness to 00000013 (or anything else I tried) didn't appear to make any appreciable difference. It didn't matter whether I changed the /proc file through the GUI or via the command line.

By any chance did you happen to try the "pep_hscaler_sharpness" setting? Maybe the h stands for the horizontal scaler setting?

No, I didn't try changing it. I'll have a go later today.
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Re: T2 - blurry picture at 576i/p

Post by prl » Sun Nov 05, 2017 14:54

prl wrote:
Sun Nov 05, 2017 13:26
sonicblue wrote:
Sun Nov 05, 2017 10:08
prl wrote:
Wed Nov 01, 2017 11:05
Changing /proc/stb/vmpeg/0/pep_scaler_sharpness to 00000013 (or anything else I tried) didn't appear to make any appreciable difference. It didn't matter whether I changed the /proc file through the GUI or via the command line.

By any chance did you happen to try the "pep_hscaler_sharpness" setting? Maybe the h stands for the horizontal scaler setting?

No, I didn't try changing it. I'll have a go later today.

I tried 00000000, 00000013 and 000000ff as values for /proc/stb/vmpeg/0/pep_hscaler_sharpness, and for 576i output from the Beyonwiz, those values didn't make any significant difference to the fine vertical lines in either the TV screen display (as scaled by the TV), or in the high resolution screen grab in Open Webif (rescaled by Open Webif).
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Re: T2 - blurry picture at 576i/p

Post by sonicblue » Sun Nov 05, 2017 22:35

prl wrote:
Sun Nov 05, 2017 14:54
I tried 00000000, 00000013 and 000000ff as values for /proc/stb/vmpeg/0/pep_hscaler_sharpness, and for 576i output from the Beyonwiz, those values didn't make any significant difference to the fine vertical lines in either the TV screen display (as scaled by the TV), or in the high resolution screen grab in Open Webif (rescaled by Open Webif).

Thanks for that. Just some speculation...maybe the pep_hscaler_sharpness is like a sub-control of pep_scaler_sharpness? So maybe pep_scaler_sharpness needs to be set to something other than 0 as well to even activate the sharpness algorithms to begin with. Just a guess, I'm probably wrong, and you're probably sick of me asking you to do things :)

But if you're going to test, I reckon it's better to test at 576p, because I think TV-side filtering is less likely at 576p than i.

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Re: T2 - blurry picture at 576i/p

Post by sonicblue » Wed Nov 08, 2017 12:00

To ensure deinterlacing is taken out of the equation I've added to the first post a 576p version of the test pattern. Also added 1080i and 1080p versions for completeness.

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Re: T2 - blurry picture at 576i/p

Post by prl » Wed Nov 08, 2017 13:00

I don't have a TV with native 1080 line resolution.
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Re: T2 - blurry picture at 576i/p

Post by MrQuade » Wed Nov 08, 2017 13:08

I can do some testing later tonight.

However, with your original video, I found that with the T4 outputting at 1080p, the 576i test pattern looked nigh on perfect on my new TV.
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Re: T2 - blurry picture at 576i/p

Post by sonicblue » Wed Nov 08, 2017 14:35

MrQuade wrote:
Wed Nov 08, 2017 13:08
However, with your original video, I found that with the T4 outputting at 1080p, the 576i test pattern looked nigh on perfect on my new TV.

Yep its the same on my T2; the only affected HDMI modes seem to be 576i/p and 480i/p.
MrQuade wrote:
Wed Nov 08, 2017 13:08
I can do some testing later tonight.

Does that mean you have a U4 :shock:

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Re: T2 - blurry picture at 576i/p

Post by MrQuade » Wed Nov 08, 2017 15:08

sonicblue wrote:
Wed Nov 08, 2017 14:35
Yep its the same on my T2; the only affected HDMI modes seem to be 576i/p and 480i/p.
I still think you are best off just outputting at 1080p and leaving it as such. No point wasting time with outputting in lesser resolutions.
sonicblue wrote:
Wed Nov 08, 2017 14:35
Does that mean you have a U4 :shock:
No I don't, I meant to test the higher res videos on the T4, but the results are likely to be very similar to the T2.
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Re: T2 - blurry picture at 576i/p

Post by Grumpy_Geoff » Wed Nov 08, 2017 15:23

MrQuade wrote:
Wed Nov 08, 2017 15:08
...
sonicblue wrote:
Wed Nov 08, 2017 14:35
Does that mean you have a U4 :shock:
No I don't, ...

I was sure you were going to be that third pre-release U4 tester - shiny new 4K TV, and you were a pre-release T2 tester weren't you? :wink:
My thinking was it was stated as being on its way to that 3rd tester, and it doesn't take more than a few days to get from Sydney to anywhere else in 'Oz - apart from the 8 days it takes to get here.

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Re: T2 - blurry picture at 576i/p

Post by sonicblue » Wed Nov 08, 2017 16:30

MrQuade wrote:
Wed Nov 08, 2017 15:08
I still think you are best off just outputting at 1080p and leaving it as such. No point wasting time with outputting in lesser resolutions.

I have tried really hard to appreciate the upscaled picture of the T2, but just find on actual SD content the picture sharpness is at times unwatchable, to the point where actors faces will appear almost out of focus. Meanwhile the Tivo outputting 576i/p looks quite good (using a remote controlled HDMI switch to compare). I even find the T2 looks better at 576p despite the filtering issue.

I have a theory why this might be the case: when the TV gets a 576 signal, the TV's own sharpness filter gets applied BEFORE upscaling, so the sharpening artefacts themselves get upscaled and enlarged, which preserves the look of the TV's sharpness filter. Whereas when feeding it upscaled 1080 from the BW, the TV's sharpness filter has to operate on mostly upscaled/interpolated pixels, which are perhaps lower inter-pixel contrast and not as sensitive to sharpness algorithms.

I notice in Media Player Classic Home Cinema there is an option to apply sharpening before or after upscaling, and I see a similar thing: notably increased sharpness if applied before upscaling rather than after (before , after).

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Re: T2 - blurry picture at 576i/p

Post by MrQuade » Wed Nov 08, 2017 18:05

sonicblue wrote:
Wed Nov 08, 2017 16:30
I have a theory why this might be the case: when the TV gets a 576 signal, the TV's own sharpness filter gets applied BEFORE upscaling, so the sharpening artefacts themselves get upscaled and enlarged, which preserves the look of the TV's sharpness filter. Whereas when feeding it upscaled 1080 from the BW, the TV's sharpness filter has to operate on mostly upscaled/interpolated pixels, which are perhaps lower inter-pixel contrast and not as sensitive to sharpness algorithms.
Ahh interesting. I think that is the difference that we are experiencing here then. I have all sharpness controls turned off off off on my equipment. I prefer the content to remain as it was produced without introducing new processing artefacts from display filtering.
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Re: T2 - blurry picture at 576i/p

Post by sonicblue » Wed Nov 08, 2017 19:38

MrQuade wrote:
Wed Nov 08, 2017 18:05
Ahh interesting. I think that is the difference that we are experiencing here then. I have all sharpness controls turned off off off on my equipment.

Fair enough, and I'm aware videophiles like to run sharpness at 0 :)

Personally I like to have sharpness at the highest possible setting I can tolerate without visible ringing artefacts intruding into the viewing experience. I'm currently using a sharpness setting of 30 on my Samsung plasma (default being 50). This is slightly higher than the Movie mode default of 20. At 20 the DVE sharpness pattern says its ok as there are no visible halos around the black text, but higher than 20 the halos start to become visible, so I am slightly into the naughty zone :D

MrQuade wrote:
Wed Nov 08, 2017 18:05
I prefer the content to remain as it was produced without introducing new processing artefacts from display filtering.

Fair enough, but keep in mind when SD is upscaled to HD we're turning square wave pixel patterns into sine wave which reduces edge contrast compared to how it would look on a native 720x576 display without any upscaling (edit: only for computer generated content which isn't anti-aliased to begin with - forgot about that :) ). MadVR has a bunch of interesting de-ringing and "de-bloating" filters which remove unwanted ringing artefacts while preserving the added edge contrast, and I find the results can be quite spectacular.
Last edited by sonicblue on Thu Nov 09, 2017 00:08, edited 1 time in total.

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Re: T2 - blurry picture at 576i/p

Post by peteru » Wed Nov 08, 2017 22:48

Let me get this right...

sonicblue prefers a picture with noise that has been sharpened to introduce and magnify high frequency aliasing errors.

T-series deliver picture where the picture has been filtered to remove high frequency error above the Nyquist frequencies.

What to do?

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Re: T2 - blurry picture at 576i/p

Post by sonicblue » Thu Nov 09, 2017 01:24

peteru wrote:
Wed Nov 08, 2017 22:48
sonicblue prefers a picture with noise that has been sharpened to introduce and magnify high frequency aliasing errors.

I think the camera anti aliasing filters the aliasing errors, then low bit rate softens it more, then bob deinterlacing halves the resolution again when the scene is moving , and my viewing distance is too far back to even resolve detail if it was even there...in the end I am not left with much resolution! For a pristine source viewed close up on a monitor I would definitely be using a much lower sharpness setting, if any.

peteru wrote:
Wed Nov 08, 2017 22:48
T-series deliver picture where the picture has been filtered to remove high frequency error above the Nyquist frequencies.

I looked into this some time ago and found something like 67% line widths per picture height at 30%MTF was what most digital cameras were capable of resolving. From memory it increased to something like 80% with supersampling. Detail above the Nyquist frequency (50% , assuming that's the figure you were referring to) would still likely contain actual resolution at >=30%MTF so I would hesitate to call it "error" or "noise". But then the low bit rates and bob deinterlacing on movement, so maybe there is nothing there to see anyway.
Last edited by sonicblue on Thu Nov 09, 2017 04:17, edited 1 time in total.

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Re: T2 - blurry picture at 576i/p

Post by peteru » Thu Nov 09, 2017 01:45

I was actually thinking more along the lines of what you preference was based on the samples featuring The Doctor and Janeway.

As a single frame, the sharper and noisier picture may have slightly more appeal, but when you have those in a video sequence, the noise becomes quite obvious on the temporal scale. Combine that with the processing that most displays tend to do these days and the noise will actually create some really annoying artifacts. For example, Samsung's motion plus will create a right mess of a panning/rotating picture with a lot of high frequency components. The slightly softer picture will create a less obvious mess.

The PEP block in the Broadcom chipsets has a few settings for controlling the mosquito and block noise as well as digital contours. While these will soften the picture, the result on low bitrate (aka Australian FTA broadcasts) can be favourable. They are not applied by default, but the controls are there.

If you really want sharpening on your picture, my suggestion would be to apply it as late as possible in the pipeline. In general, you want as few picture transformations as possible so that you prevent concatenation errors.

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