ExBlend deblender - v1.04 - 18 Dec 2018

[CruJones]

Thanks for the ExBlend plugin StainlessS. I recently taught myself QTGMC deinterlacing with AviSynth to work on a some DVD's I have. When I stumbled upon your plugin, I recognized that telecine pattern of double blend every 5 frames in an old 2 min clip from 1996 that I was hoping to fix. In mode 2 after the XBD scan it definitely improved the footage with 25 fps to get rid of the ghosting from the original but it's not perfect. There's a number of fades from one sequence to another in the editing and in those moments the frames seem a little off. I'd like to try and see if I can correct any of this further but without scripting experience I'm probably way in over my head with this. Any advice is much appreciated though. Cheers!

[StainlessS]

I guess that you're lucky that it worked at all, was really only intended for when NTSC telecine clip was downsized to half height via eg verticalReduceBy2(), producing 2 out of 5 blending.
Fades will/may cause ExBlend to lose sync, and take time to get back in-sync, ExBlend is a bit particular in the exact cause of blending, some have used SRestore() instead for same [likely that fades will prove problem there too].
Where loses sync [at eg fades] might want to look at the Overrides arg [string, filename, MODE=1 only].
Set Override at first blend pair following 'de-sync'.
Good Luck.

EDIT: From Settings.txt

string Override  Default "", (not set), eg "Override.txt" (New to v1.01)
                 Filename of file to force manual override the blend detections.
                 In v1.03, is only used in MODE=1. Neither Mode 0 nor Mode 2 
                 allows a manual override, you must force the override's in mode
                 1, v1.03 extends the override ability and greatly increases it's effectivness. 
                 Also, logging will assist in setting up the overrides file.

                 Required command format:-

                 444=h1
                 555
                 666=*4

                 In the above case, frame 444 is set to HINTED, ie Not A Blend. The number
                 after the 'h' denotes the hinted count, in this case 1, eg 444=h2 would
                 set two consecutive hinted frames.

                 555 will be set to a SHORT BLEND PAIR ie (H12H), frame 555 (in this case) will
                 be set to blend index 1, 556 to index 2, and the frames before and after the
                 blend pair to HINTED. NOTE, in this case frame 555 is the 1st BLEND index and
                 NOT the first hinted frame.

                 Frame 666=*4 will set an override at frame 666 to 4 LONG BLEND PAIRS. A long
                 blend is shown (in logs) as (H12HHH) for FILM or (H12HHHH) for PAL. The frame
                 (in this case 666) is the position of the 1st blend index, it will (on only
                 the first LONG BLEND PAIR) be preceded by a hint, and the blend pair followed
                 by 3 or four hints depending upon whether FILM or PAL mode is in effect. As in
                 above case, '666=*4' would yield a result of (H12HHH12HHH12HHH12HHH) if in
                 film mode, or (H12HHHH12HHHH12HHHH12HHHH) in PAL.
                 With metrics shown, the 'M' flag will show where individual manual override 'H'
                 hints were set, or blend index 1 postions of either short or long blend pair
                 overrides (in the 666 example, it will flag the positions of all the 1's
                 within the parenthesis['(' and ')'] ).

                 ExBlend is intended to correct clips that do not stay in sequence, if you have
                 a clip that does stay in sequence (and you are sure of that), you can force
                 ExBlend to stay in sequence too using the manual override command file. If say
                 the first, 1st blend index is at frame 2, you could create a text file containing
                 the manual override command:-

                 2=*1000000

                 Thats it. (you would also need to set correct pal/film mode and such). Here
                 we gave a command to set 1 million LONG BLEND PAIR's, it will cease when
                 it comes to end of clip, and in the logs will tell you how many it actually set.
                 This excessive repetition count will not be considered an error by the override
                 command parser, however, trying to start a new command outside of clip range will
                 be considered an error. Also, NOTE, all manual override commands MUST be in ascending
                 order of frame number, you are NOT permitted to override previously set overrides,
                 some sort of order has to be maintained. As an aid (and byproduct of this strict
                 ordering) the parser can tell you (in logs) where the next permissable command
                 may be set. If trying to set up a manual override command file, use the logs, they
                 are your friend when trying to do this.

[CruJones]

Thanks for the response and info StainlessS. The clip that I was using the ExBlend on was not from a DVD source by the way but rather a TV capture from a Cinemax/HBO program which originally aired in 1996. (I was probably unclear in my first post and see why you were surprised it worked). I’m not sure of the source of the original capture but ExBlend has definitely improved a lot of the footage. Thanks again!

[Julek]

The Canaan blu-ray suffers from a chroma blend, I was trying to fix it via vapoursynth but was getting a worse result than Yousei-Raws.
So I went to see if AVS had something better and ended up discovering ExBlend which has the same result as my script.

My deblend function: https://github.com/dnjulek/jvsfunc/b...vsfunc.py#L148
In some scenes the result was really good: https://slow.pics/c/zz4RFF80
But in others the Yousei-Raws result was cleaner: https://slow.pics/c/Ff8LeIjy
I was wondering what Yousei used to fix it.
The blend probably happened because the video was upscaled from 720p to 1080p, destripe to 360p fixes the luma: https://pastebin.com/2eVi3ijq
Video samples: https://drive.google.com/drive/folde...J3MS3ZVBfOx8VM

[Zarxrax]

Something doesn't seem to be working right when I try to use Exblend.
When I use mode=1, it actually seems to detect the blends, and doesn't display the blended frames in the output. But when I use mode=2, it just seems to leave them in and create new blends!

This is just a basic script loading a video through FFMS2 and then using Exblend(mode=1), doing a scan of the whole video, and then changing to mode=2.

Am I doing something wrong?

[StainlessS]

Attachments can take forever, and show script probably more informative.
See Here for future Image post:- https://forum.doom9.org/showthread.p...14#post1959414

IIRC, VISTA+, broke the current directory relative file path stuff, and it might not work properley without
full path [or at least have the ".\" part for current dir relative eg ".\somefile.txt", a plain "somefile.txt" can fail].

So, dont rely on default paths for old Exblend, specify full path or proper current path relative preceding filename with ".\"

EDIT: I think W7 [or maybe W10] defaulted to saving any files without ''.\" in VirtualStore (whatever that is),
again. specifiy full path and ideally not in root of C: drive.

[StainlessS]

Zarxrax, Did you ever find a solution for this ?

Originally Posted by Zarxrax

Curious if it is possible for avisynth to do anything like this:
Take a frame or short clip from one video, and search for it's location in another video. While the 2 videos contain the same general footage, they may differ greatly in quality, resolution, cropping, and so on.

I have hundreds of clips that I am trying to locate within tens of hours of footage, so some semi-automated method would be much simpler than manually searching through all of the footage for every single clip.

If not avisynth, perhaps it might be possible using ffmpeg or some other tool?

And if not, are you still interested in a possible [maybe - sometimes] solution ?
Once prepped (make SEARCH clip, maybe 320x240 or bit bigger copy of big file, stretching to Max dynamic range PC_Levels, then make fingerprint file),
search on your single FIND Frame should take maybe max 1 second [find or fail].
Could even auto make FIND Clip same as SEARCH clip size etc, pick out say 10 frames from find clip, and show result SEARCH clip frame that matches first found
frame of FIND clip, with a small number of FIND frames (maybe 10) should nearly always find at least one of them.

Would take time to make small dimension SEARCH clip, and then maybe eg 16 mins [on my old XP machine core duo for 2 hours Jurassic Park DVD at DVD rez]
to do the fingerprint file [need keep both small SEARCH clip and fingerprint file]. After that, real fast to find/fail_find frames.
(When first written, was for EXACT same frame to search for, had it doing something like 3 Million frames/ second on the XP core duo, sadly, frames turned out not to be
exactly the same, and I spent 9 months trying to get it working with hit/miss results and quite a bit slower due to match tolerance).
https://forum.doom9.org/showthread.p...ht=RT_QwikScan

EDIT: The first posts in linked thread were of script functions, was later implemented as RT_Stats plugin.

[Zarxrax]

Originally Posted by StainlessS

Attachments can take forever, and show script probably more informative.
See Here for future Image post:- https://forum.doom9.org/showthread.p...14#post1959414

IIRC, VISTA+, broke the current directory relative file path stuff, and it might not work properley without
full path [or at least have the "." part for current dir relative eg ".\somefile.txt", a plain "somefile.txt" can fail].

So, dont rely on default paths for old Exblend, specify full path or proper current path relative preceding filename with "."

EDIT: I think W7 [or maybe W10] defaulted to saving any files without ''." in VirtualStore (whatever that is),
again. specifiy full path and ideally not in root of C: drive.

I updated my post with the image link. It does not seem to be an issue with the file paths. The plugin correctly outputs the file in the same folder as the .avs without me having to specify anything. But I did try manually specifying the path just to be sure.

Regarding your qwickscan function, thanks, I'll hold onto that in case I need something like that again in the future.

[StainlessS]

Zarx,
OK, let me know if you want assistance with the QwikScan thingy. [is some basic functionality to search for frame somewhere in RT_stats thread (needs same frame size - try LumaTol=0.0 for identical frame)].

Can you post your scripts, also which version EXBlend (I aint used original for long time, I last used the Beta, think I fixed the path thing in Beta).

[Zarxrax]

Originally Posted by StainlessS

Zarx,
OK, let me know if you want assistance with the QwikScan thingy. [is some basic functionality to search for frame somewhere in RT_stats thread (needs same frame size - try LumaTol=0.0 for identical frame)].

Can you post your scripts, also which version EXBlend (I aint used original for long time, I last used the Beta, think I fixed the path thing in Beta).

Script is simply just FFMS2("input.mov").ExBlend(mode=1)
I am using the 20181218 x64 version (I assume its the latest).

[StainlessS]

OK, it is the latest.

Well I dont know what to say, You script shows that you did not set the ExBFile to anything eg "D:\ExBlend.XBD", suggest that you do give specific path (not C:\) and filename at very least.
Also, the image shown suggests that it only found 2 BlendPairs at frame 419, methinks maybe you just jumped there after clip open, and so metrics mean nothing at all.
Also, unless you did COMPLETE scan from start of clip to end, then XBD file will NOT be created.
Metrics show PAL = -1, (default, ie unknown/auto detect mode), once you figure out what clip you have, then you need set PAL=0 (not PAL) or 1=PAL [Better detect when not guessing].
After FULL scan at correct PAL and Mode=1, then Ratio% should be ideally green and about 95%+, 98% a lot better, less than about 95% forget it, it aint the right detector plugin.
You have HIGH Ratio (too high actually due to not knowing whether should be PAL=0 or 1, and only 2 blends detected).

Suggest do as above, full scan, and check that on last frame that Metrics are at least 95+%, then close script and that ExBlend.XBD exists when you closed. [not written until closed].

Then can switch to Mode=2 (and can also then set Decimate=True otherwise there will be dupes to be decimated in result of mode 2 pass).

EDIT: I think thats about right, long long time since i used it.
EDIT: Seems that in Mode=2, Decimate default is also true, so you dont need set that. [Quickref has table of defaults and settings for each mode].
EDIT: Not sure, maybe you dont need supply ExBFile="Exblend", think should be ok without doing anything, but not sure if path is needed,
I dont have test clip, I shall try with any old clip and see what happens.

[StainlessS]

OK, just tried it with any old clip, did not of course have proper detections, but still created ExBlend.EXB file in current directory [I must have fixed directory stuff on last update],
and no longer needs path, indeed you must just give "ExBFile" or similar, the function of ExBFile has changed a little since older version,
it used to be a filename [and had path probs on Vista+], but has changed to be a Project Name, several files are created using the Project name, and the ".XBD"
part is auto appended to the correct one.

Also, pass 1 can just use

Avisource("...")
ExBlend() # Default is now ExBlend(Mode=1)

And can use VDub2() Video Analasis Pass for fast scan, will stop on last frame to see metrics [It used to jump back to frame 0 until I asked to be changed].
Close file and ExBlend.XBD file and also ExBlend_Decimated.TXT will be created, [ClipClop command file with frame list of frames that will be UnBlended on pass 2,
can use for selective denoise of only Unblended frames of the decimated result].


Pass 2

Avisource("...")
ExBlend(Mode=2) # Default Where Mode=2, is now ExBlend(Mode=2, Decimate=True)

Latest version was big change and many defaults changed with mode. [needed to be changed because of massive possibilites added by decimation and other stuff].
From the QuickRef [default for both mode=1 and mode=2]

Mode 1: (ExBlend v1.03+ Scan & Store Data, default, Need to do this before using MODE==2) ------------------

  Arg         Type      Min      Max     Default      Comment

  clip        clip      clip     clip    NONE         YV12 & YUY2 PROGRESSIVE
  Pal         int       0        1       0            PAL -1 Not Allowed (Error)
  LockThresh  float     0.0      100.0   1.0          default rarely needs change.
  IThresh     float     0.0      100.0   3.0          default rarely needs change.
  Show        int       0        5       5            Metrics (0=OFF,5=FULL)
  Exbfile     string    -        -       "ExBlend"    Project: logs,'Exbfile'.XBD & Decimated (Mode 2) Frames Cmd file.
  Ver         bool      False    True    False        ALL ARGS IGNORED if true
  Revip       bool      False    True    False        Reverse Metrics Direction when show > 1
  Override    string    -        -       ""           Input Override Command file
  Lv          int       0        5       0            0=Off, 1=ERR, 2=WARN,3=INFO,4=VERBOSE,5=DEBUG (logfile)
  Dv          int       0        5       0            0=Off, 1=ERR, 2=WARN,3=INFO,4=VERBOSE,5=DEBUG (DebugView)
  Disp        int       0        3       1            Display mode, 0=BLENDED(original), 1=EXBLEND, 2= SRESTORE, 3=COMPONENT, (4=ADJACENT Invalid)
  DClip       clip      -        -       UNSET        Denoised Detection Clip, Same colorspace & dimensions as Clip.
  CompUB      int       0        2       2            Component Unblend Mode for DISP display mode
  Decimate    bool      -        -       -            IGNORED  (MODE 2 ONLY)
  Decompix    int       1        2       1            IGNORED  (MODE 2 decimated ONLY)
  DecClpIx    int       <0       255     1            Clip index used in eg Exblend_Decimated.Txt, <0 == NONE.
  Debug       bool      false    True    False        Switch On: ERRORS, WARNINGS and DEBUG logging (ie 1,2 and 5)


Mode 2: (Final Output mode, needs MODE 1 pass 1st.) -------------------------------------------------------------

  Arg         Type      Min      Max     Default      Comment

  clip        clip      clip     clip    NONE         YV12 & YUY2 PROGRESSIVE
  Pal         int       -        -       -            Ignored, Set from 'Exbfile'.XBD
  LockThresh  float     -        -       -            Ignored, Set from 'Exbfile'.XBD
  IThresh     float     -        -       -            Ignored, Set from 'Exbfile'.XBD
  Show        int       0        5       0            Metrics (NON-DECIMATED:0=OFF,5=FULL | DECIMATED:0=OFF,>0 ON) [DEFAULT different to modes 0 & 1]
  Exbfile     string    -        -       "ExBlend"    Project: (logging, Inputs Project Mode 1 XBD file)
  Ver         bool      False    True    False        ALL ARGS IGNORED if true
  Revip       bool      False    True    False        Not used when Decimate (Metrics are different).)
  Override    string    -        -       -            IGNORED, Set in Mode 1
  Lv          int       0        5       0            0=Off, 1=ERR, 2=WARN,3=INFO,4=VERBOSE,5=DEBUG (logfile)
  Dv          int       0        5       0            0=Off, 1=ERR, 2=WARN,3=INFO,4=VERBOSE,5=DEBUG (DebugView)
  Disp        int       0        4       1            If Decimate, 0_BLENDED, 1_EXBLEND, 3_COMPONENT & 4_ADJACENT valid (2_SRESTORE converted to EXBLEND)
  DClip       clip      -        -       UNSET        Usually as Mode 1 (or NONE), Same colorspace as Clip.
  CompUB      int       0        2       2            Component Unblend Mode for DISP display mode
  Decimate    bool      false    True   True    
  Decompix    int       1        2       1            Decimated Component Index. Valid if DECIMATE & disp=0_BLENDED/3_COMPONENT/3_ADJACENT else Ignored.
  DecClpIx    int       <0       255     1            IGNORED (MODE 1 ONLY)
  Debug       bool      false    True    False        Switch On: ERRORS, WARNINGS and DEBUG logging (ie 1,2 and 5)



To use ExBlend(), you need to do a scan of the clip first using eg:

  ExBlend(clip, Mode=1) # AssumeFPS(250.0)

  or

  ExBlend(clip, Mode=1,dclip=DCLIP) # AssumeFPS(250.0)

  Where DCLIP is a denoised detection clip if required.

  Scan through the file and it will create an ExBlend.XBD file for Mode 2 as in below example.

  ExblendedClip=ExBlend(clip, Mode=2,dclip=DCLIP)

EDIT: Also, its v2.60 colorspace cabable [docs need update].
and Default on mode=1 is PAL=0, not pal, so thats ok.
So really, I presume that you just did not do complete scan of the clip in mode = 1 [but need also check the Ratio % on last frame].

[Zarxrax]

Hmmm, well I know it is NTSC content that was re-edited on an NTSC vhs deck, so I suppose that might have messed with the fields in a way that made it incompatible with this plugin. Also with it being anime, it was mostly animated on the 2's so most of the time there is only 1 visible blended frame per group of 5 frames. I tried the pal=0 setting with no improvement.

You are right that for my mode=1 screenshot, I did directly seek to that area. After some more investigation, if I have it on mode 1 and play from the beginning (or encode the output of the full scan and watch it back) I can see that it doesn't actually get fixed in mode 1. Only if I directly seek there, it will fix that section, I suppose by sheer chance. I just saw that it seemed like the plugin was actually working there and I guess I got my hopes up.

[StainlessS]

NTSC content that was re-edited on an NTSC vhs deck

Well that there would make it fail at [EDIT: unless extreme care taken] every edit and need re-acquire lock on the blend sequences.

most of the time there is only 1 visible blended frame per group of 5 frames

The plug is specifically for 3 good 2 blend sequences, I did not know what caused it when i wrote the plugin,
apparently ActionMan33 [EDIT: ActionMan133] wrote a script to fix similar stuff [and theres at least one more as well as SRestore].
It turns out that [I think] most clips fixable with Exblend are result of
VerticalReduceBy2 (clip), HorizontalReduceBy2 (clip) OR, ReduceBy2 (clip) on Interlaced source [EDIT: 3:2 pulldown source].
However, a few changes made 2 versions ago allowed it to be used to fix a JohnMeyer clip that was not
a result of that downsizing by 2, but had been an NTSC interlaced resize [EDIT: 3:2 pulldown source].

Also, I made mistake in saying was in AutoPal mode, I saw '?' flag and mistook it for the upside down '?' which flags AutoPal mode.

So, sorry, this plug is not for you, this time.

EDIT: Sorry, NOT NTSC interlaced resize, NTSC 3:2 pulldown telecine film resize.

EDIT: The PAL mode was to detect 4:2 [good/blend] sequences, I had no idea at the time what it was that caused the problems,
and was easy to add just incase they existed in the wild.

There were at one time a number of "Betty Page" clips available [maybe downsized for Video CD] which were easily available via Google,
[type in her name a a bunch of them were there] these all seemed to demo the problem. [those available last time I tried were much lesser
quality [flv maybe] from sites such as YouTube, but I think still un-exblend perfectly.

EDIT: A quick look and the BP videos are not at top of google list any more [mostly stuff about the Movie - The Notorious Bettie Page].

EDIT: I was actually doing a working version that fixed 3 (or 4) good, 3 blend, but dont know if I've even still got the source.
(the test clips were all artificially created)

EDIT: The original sorta reasonable quality betty page clips were actually mpeg (mpg1 so VCD I think).

[Zarxrax]

Well thanks. I previously wasn't able to obtain a good result with srestore, but I revisited it now and tried a few different settings, and I am getting fairly decent results from it now. Deblending is such a complex topic to wrap my head around.

[Selur]

@StainlessS: Any plans for an Vapoursynth port of Exblend?

[Selur]

I used:

ClearAutoloadDirs()
SetFilterMTMode("DEFAULT_MT_MODE", MT_MULTI_INSTANCE)
LoadPlugin("I:\Hybrid\64bit\Avisynth\AVISYN~1\LoadDll.dll")
LoadDLL("I:\Hybrid\64bit\Avisynth\avisynthPlugins\libfftw3f-3.dll")
LoadPlugin("I:\Hybrid\64bit\Avisynth\AVISYN~1\LSMASHSource.dll")
LoadPlugin("I:\Hybrid\64bit\Avisynth\AVISYN~1\TIVTC.dll")
LoadPlugin("C:\Users\Selur\Desktop\ExBlend_x64.dll")
Import("I:\Hybrid\64bit\Avisynth\avisynthPlugins\mtmodes.avsi")
# loading source: C:\Users\Selur\Desktop\Courage the Cowardly Dog S02E17E18 SOURCE.mkv
# color sampling YV12@8, matrix: bt709, scantyp: telecine, luminance scale: limited
LWLibavVideoSource("C:\Users\Selur\Desktop\COURAG~1.MKV",cache=false,dr=true,format="YUV420P8", prefer_hw=0)
# current resolution: 720x480
# deinterlacing


TFM() # field match back to a film frames
TDecimate() #remove duplicates
AssumeFrameBased()
org=last
Exblend(mode=1, Exbfile="e:\Exbfile")
#Exblend(mode=0,revip=true, show=0)
StackHorizontal(last, org)


# filtering
# Converting from 8 to 10bit for encoder
ConvertBits(10)
# setting output fps to 23.976fps
AssumeFPS(24000,1001)
PreFetch(16)
#  output: color sampling YV12@10, matrix: bt709, scantyp: progressive, luminance scale: limited
return last

and called

avs2yuv64.exe c:\Users\Selur\Desktop\test2.avs NUL

Assuming that this would create "e:\Exbfile.XBD" which it does not and thus changing the script to

Exblend(mode=2, Exbfile="e:\Exbfile")

aborts with:
ExBlend: ERROR, Mode 2 XBD, Cannot open BXD file "e:\Exbfile.XBD".

-> How to use this properly?

[StainlessS]

Any plans for an Vapoursynth port of Exblend?

Nope, I dont do the vapourSynth thingy, yet. If somebody else wants to do conversion, I have no problems with that.

TFM() # field match back to a film frames
TDecimate() #remove duplicates
AssumeFrameBased()
org=last
Exblend(mode=1, Exbfile="e:\Exbfile")

Above in red tastes a bit off.
ExBlend is intended for clip that should have been de-telecined prior to resize down to VCD/SVCD size, where would create 3/2 blending [3good/2blend].

Stuff in red would seem to provide exblend with NTSC film rate progressive, not NTSC telecined(29.976), badly resized downwards.

aborts with:
ExBlend: ERROR, Mode 2 XBD, Cannot open BXD file "e:\Exbfile.XBD".

I can only imagine that ExBlend did not find any blended pairs, and so the XBD file is empty/non existing.
[EDIT: If indeed it was the type of badly resized clip that Exblend is intended for, then the stuff in red would likely bugger that up and make ExBlend fail to find anything]
[EDIT: You would best look at Exblend Metrics in Avisynth, and detect %]

[Selur]

Background:
A user of Hybrid wrote to me:

I've got an American NTSC VHS, which is an NTSC 29.98 conversion of a PAL shot on video movie. The original master is lost. I have it captured via S-Video.

and that no matter what he did in Hybrid, he couldn't get rid of the ghosting. Looking at the fields I noticed that some of the fields already had the ghosting.
Since I rembered I got rid of similar ghosting a few years back which ExBlend, I wanted to try with the latest version.

If I run ExBlend in mode=0 it properly finds some of the existing blended frames and 'fixes' them.

But seeing that mode=0 is depricated and not the way one should use the filter I wanted to try it using 2passes.
Problem is:

Exblend(mode=1, Exbfile="e:\Exbfile")

doesn't create a 'e:\Exbfile.xbd' file or any other file and thus mode=2 aborts with the above message.
-> So I don't know if this is a bug in ExBlend or whether I don't know how to properly use it.

Cu Selur

Ps.: not sure whether ExBlend was meant for this, but it helps with at least some of the blends which is why I would like to use it. I can stick with mode=0, but thought that since it's depricated it would be wise to figure out how to use the 2pass processing.

[StainlessS]

See this thingy here:- https://forum.doom9.org/showthread.p...nd#post1860483
where was used with a bit of a Didee kludge, and it worked ok.
Also has in post problem that seemed to come into existence with W7 (maybe Vista), for paths.

Also, just in case you are using older Ver$, here is the last 2018 ver[v1.04]:- https://www.mediafire.com/file/ejqfg...81218.zip/file

Also, I seem to remember that no XBD file will be generated unless a complete scan is done {ie, it does not write a partially complete file}
[also, Might possibly abort write if detections were really not good, flagged in metrics in RED].
I think also writes message to DebugView when writing XBD, or tells if skipping write. [check it out].