Cant stop artifacts from appearing

[killerteengohan]

I learned on here why my Blu-Ray being scaled down to SD had incorrect colors on playback for me. Here is the thread that it was talked about on here. Its alot of good info from Jagabo and explains my issue I am having better. https://forum.videohelp.com/threads/382861-Color-keep-changing-and-I-cant-get-it-to-stop

I was taught about Rec601 and Rec709 colorspaces for the first time. Also, my media players or devices were ignoring the flags in the settings and were going by resolution instead of what the flags said. MadVR had it working for people with that, but anyone without it were seeing incorrect colors like I was. So I was told to change the Rec709 into Rec601 using avisynth instead of the h.264 flag settings with this Colormatrix(mode="rec.709->rec.601", clamp=0, threads=0) and it worked perfectly.



This time I am wanting to do the opposite. I have a DVD that I want to scale to 720p and I am trying to convert it from Rec601 into Rec709 with this Colormatrix(mode="rec.601->rec.709", clamp=0, threads=0)

It is doing its job when it comes to keeping the colors correct, but I am having a bit of an issue with this. It looks like it is introducing combing artifacts into the video that look horrible.

http://screenshotcomparison.com/comparison/117831



I added interlaced=true and it got rid of those heavy artifacts but it still seems to have some very minor ones showing up in certain places. This is what it looks like after interlaced=true is added in.

http://screenshotcomparison.com/comparison/117827



I took out interlaced=true and moved Colormatrix(mode="rec.601->rec.709", clamp=0, threads=0) to after the IVTC was done to the video. The rest of the noticeable combing artifacts seem to disappear but I now see certain darker splotches or artifacts appearing where they were not at before. Its very noticeable around her hips area. This is what it looks like now.

http://screenshotcomparison.com/comparison/117833



Here is Deinterlaced=true vs being used after IVTC. You can see the leftover artifacts that were in it until I moved it after IVTC.

http://screenshotcomparison.com/comparison/117832



Why am I getting these artifacts and can I keep them from happening when changing the Colorspace? I stopped the combing artifacts by placing it after IVTC, but what about the darker color splotches like on her hips area? Is there no way around those?

http://screenshotcomparison.com/comparison/117833

[aedipuss]

there aren't any ok reasons to upscale. just play the original. all you'll end up with is crappier videos.

[jagabo]

Your source appears to be an interlaced (hard pulldown) DVD. After IVTC use vInverse() to eliminate residual combing caused by slightly different intensities or colors between the source's adjacent interlaced frames, or between tape heads from the analog tape.

[killerteengohan]

there aren't any ok reasons to upscale. just play the original. all you'll end up with is crappier videos.

That's not always the case to everyone. Using AVISynth to scale a 480p SD video usually appears to do a better job than the media player or DVD/Blu-Ray player scaling 480p to fill your HDTV screen.


Here is an example. I find the AVISynth scale to look quite a bit better than media player or DVD/Blu-Ray player doing it when watching on an HD display.

http://screenshotcomparison.com/comparison/117847

Personally I like the more clear image and thinner, less fuzzy looking lines in the AVISynth scaled version.


Here is another example.

https://forum.videohelp.com/images/imgfiles/tLLDSk8.png

Left = Media player playing/scaling 480p in a 720p window.
Right = Media player playing AVISynth scaled 480p in a 720p window.

Again, I like the much more clear image and thinner, less fuzzy looking lines in the AVISynth scaled version. I'm betting Waifu2x would do even better at it than this.


So my ok reason to upscale, whether you agree or not, is that it looks a bit more clear when watching on an HD display.

[killerteengohan]

Your source appears to be an interlaced (hard pulldown) DVD. After IVTC use vInverse() to eliminate residual combing caused by slightly different intensities or colors between the source's adjacent interlaced frames, or between tape heads from the analog tape.

Thanks!, I'll give that a try tomorrow when I get back home.

You sure that's the issue? I don't see any artifacts at all when I don't try to use Colormatrix(mode="rec.601->rec.709", clamp=0, threads=0).

The interlacing is whats causing it to create the color splotches I was talking about in the last example?

I'll probly just give a sample video and script tomorrow as well. Would make it alot easier for you if you don't mind taking the time to look at it.

[poisondeathray]

You did something wrong with the screenshots , or maybe issue with your player setup.

http://screenshotcomparison.com/comparison/117833
If there was no rec conversion, and mouseover supposedly shows colormatrix conversion, the colors should be more different. There should be a 601 vs. 709 mismatch. But there isn't evidence of that in your screenshots

Maybe you should post an unprocessed clip, and your full script

[jagabo]

a sample video and script tomorrow

Yes.

[killerteengohan]

You did something wrong with the screenshots , or maybe issue with your player setup.

http://screenshotcomparison.com/comparison/117833
If there was no rec conversion, and mouseover supposedly shows colormatrix conversion, the colors should be more different. There should be a 601 vs. 709 mismatch. But there isn't evidence of that in your screenshots

Maybe you should post an unprocessed clip, and your full script

Since the MeGui preview video only displays rec.601 colors no matter what, I had to add ConvertToRGB(matrix="rec709") to the bottom or the colors would look off in the preview window. That's why the colors look the same. Ive already verified adding this to the end is not causing the issue I asked about and I take it out of the script before doing the actual encoding.

Im not using it incorrectly, I know that. I've used it with a lot of sources but this is the only one I am noticing this problem with. Then again it's also the first interlaced source I have used it on. The others were all progressive DVD or Blu-Ray.

[killerteengohan]

I'll get the unprocessed clip and script when I get back in an hour or so.

[killerteengohan]

Here is the video sample The screenshot is from the 27-28 second mark of the sample video.
https://mega.nz/#!oswD1D6b!g4zCw5dOBQLE6maT6cQsByOqGVUkA1Ume9DI49G6Tj4

[jagabo]

In your last script add vInverse() and Dup(blend=true) after tfm. Or maybe put Dup(blend=true) after ColorMatrix() instead.

[poisondeathray]

I agree, there is an issue with avisynth's colormatrix, or at least that version of it. When you strip everything else out except for ivtc, resizing (even plain resizing like spline36), colormatrix, I get the same results. Not sure why. But the underlying problem is already there, if you look closely ; it's just accentuated when you use colormatrix

Some workarounds you might try:

1) You can convert to RGB using 601 then back to YUV using 709. Not ideal, but in this case it's "cleaner" in terms of those artifacts. Probably "easiest" to do unless someone finds the issue with that colormatrix version (or maybe try a few other versions, maybe it was miscompiled, but I doubt it)

2) You can use vapoursynth's fmtconv to do the colormatrix conversion - this works. I verified. This is probably the "best" option because you stay in YUV

3) Try some post processing like deblocking. Again not ideal, will soften picture

[poisondeathray]

In your last script add vInverse() and Dup(blend=true) after tfm. Or maybe put Dup(blend=true) after ColorMatrix() instead.

vinverse works ok on some of the artifacts , so it probably is partially related to residual combing in chroma

[LMotlow]

Here is the video sample The screenshot is from the 27-28 second mark of the sample video.
https://mega.nz/#!oswD1D6b!g4zCw5dOBQLE6maT6cQsByOqGVUkA1Ume9DI49G6Tj4

I don't see consistent telecine in this sample. Maybe it's just me.

Why are you lowering quality by upscaling SD? Can't your players do it?

[killerteengohan]

Here is the video sample The screenshot is from the 27-28 second mark of the sample video.
https://mega.nz/#!oswD1D6b!g4zCw5dOBQLE6maT6cQsByOqGVUkA1Ume9DI49G6Tj4

I don't see consistent telecine in this sample. Maybe it's just me.

Why are you lowering quality by upscaling SD? Can't your players do it?

Read post #4

https://forum.videohelp.com/threads/385115-Cant-stop-artifacts-from-appearing#post2496555


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Well thanks everyone, I guess I will just have to accept them or try one of the work arounds or vinverse method.

[jagabo]

Look at the U and V channels after IVTC with

return(StackHorizontal(UtoY(), VtoY()))

You'll see lots of comb like artifacts and blocking. vinverse() smooths a lot of that away.