Fix progressive video with interlaced lines

[0peiler]

Hello Everybody,

I had to start this thread, because I couldn't find anything helpful on the internet.
I've got some videos from the internet, which are wrong deinterlaced. Which means they are progressive but still have some interlaced lines at some scenes.
Here is an example:

[Attachment 60001 - Click to enlarge]
Is there any tool/filter that can fix it?

Thanks
Pat

[davexnet]

May be able to clean it up a little, but usually this damage is baked in.
Post a representative video sample, 15 seconds probably enough

[0peiler]

Hello davexnet,
thanks for your reply. Here is a smaple.

[davexnet]

I don't think there's much improvement that can be made, but you may get other input

[BartZLederman]

Sometimes ffmpeg with the yadif filter will make some improvements, and sometimes the Libavcodec Deinterlacer can help. But I agree with the previous response that there generally isn't much that can be done about it.

[joearmstrong]

QTGMC has a repair function for bad deinterlacing artifacts:
t = QTGMC( Preset="Slower", InputType=2 )
b = QTGMC( Preset="Slower", InputType=3, PrevGlobals="Reuse" ) # Reuse motion vectors from first call for a good speed-up
Repair( t, b, 1 )

[0peiler]

Thanks for the suggestions. I'll give it a try because I have nothing to lose

[Quint]

There are also Functions like De-Bilinear or De-Bicubic. The stripes are caused by Field-Delays (not interlacing) and then resizing in that state. If you are lucky and find the right parameters you can maybe downsize to original size and then fix the field delay. But you need a lot of luck for this, I never managed it.

[rrats]

You can blur the video, thus blending the fields, but do this only if any other options don't work

[0peiler]

Thanks again for the suggestions.
Unfortunately the yadif or QTGMC couldn't fix it.
The downsize funktion sounds interesting but I have absolutely no idea what the original size could be.
I've tried some but it didn't work. Is there any tool that can give me a preview so I can downsize step by step?
A blur could be also a solution, as the lines are just in some random frames and not the whole video.

[jagabo]

Use a function that resizes but keeps the frame size. Call it with Animate().

###################################################

function vresize(clip c, int vheight)
{
	Spline36Resize(c, c.width, vheight) # resize the incoming video
	AddBorders(0,0,0,c.height-vheight) # restore the original frame size by adding black lines at the bottom
	Subtitle(string(vheight)) # show the size it was resized to
}

###################################################

LWLibavVideoSource("sample.mp4", cache=false) 

Trim(0,length=1) # isolate a good frame for testing
Loop(700,0,0) # repeat it 700 times
ConvertToYV24()
Animate(0,699, "vresize", last,20, last,720) # see it at different verical sizes

[BartZLederman]

I don't know about QTGMC / Avisynth. I use Avidemux for most editing, it can step through frame-by-frame, and it has several deinterlacing filters and a preview mode so you can see what the options do. It also has a scale (resize) function and you can set the size by pixels or percent. It's also possible to step forward one frame at a time in VLC but you have to use the "Customize Interface" option to add the step by step buttons to the control area, they're not there by default.

[Quint]

What @jagabo wrote can be a good thing to watch what happens with different parameters. The problem in this case is, that the clip had been resized while being in a pseudo-interlaced state. That means it is not enough to resize back to the original size, you have to "reverse" the done resizing as far as possible to get the original Interlace-structure, which can be corrected then. This can in many cases be done by the functions I mentioned: De-Bilinear or De-Bicubic, no other chance.
You can deinterlace or something and then try to improve the blending but this won't work, no matter how you try.

[jagabo]

Debicubic(444) worked pretty well.

LWLibavVideoSource("sample.lines.mp4", cache=false) 
AssumeTFF()
Debicubic(width, 444)
QTGMC()
Spline36Resize(width,720)

The 444 value was found with a script like the one I gave in post #11, using Debicubic() instead of Spline36Resize(). I converted to RGB rather than YV24 since Debicubic() doesn't support YV24. And 32 AviSynth is required since there doesn't seem to be a 64 bit version of Debicubic().

[Quint]

Might save my life too, once in the future! Thanks for this, @jagabo!

Edit: If the output after DeBicubic is very clean then TFM() should be enough to re-order the delayed fields. Then there would no deinterlacer like QTGMC be necessary.

[jagabo]

I used QTGMC because I thought it might clean up some of the remaining artifacts. And it wasn't clear what the actual frame rate should be.

[Selur]

Wow, DeBicubic really did a nice job.
Now one would just need an automated way to find the right height.

[rrats]

Wow, DeBicubic really did a nice job.
Now one would just need an automated way to find the right height.

Height can either be 576 or 480, if this was taken from dvd

[Selur]

@sm-p: wrong height. I'm speaking of the Debicubic parameter,...

[davexnet]

Impressive work. I didn't look at post 11 yet, so I've no idea how long it too to find the value.
Was also going to mention two or three versions of this video up on Youtube although at first glance
Jagabo's result is better than those

[jagabo]

It only took a few seconds once the script was written:

function vresize(clip c, int vheight)
{
	DeBilinear(c, target_width=c.width, target_height=vheight) # downscale
	AddBorders(0,0,0,c.height-vheight) # restore original height with black border
	Subtitle(string(vheight)) # show the vheight used for easy reference
}

LWLibavVideoSource("sample.mp4", cache=false) 

Trim(0,length=1) # get a frame for testing
Loop(700,0,0) # repeat it 700 times

ConvertToRGB()
Animate(0,699, "vresize", last,699, last,20) # show sizes 20 to 7
Bob().SelectEven()

I suspect you can get even better results by fine tuning the src_top and/or src_height parameters.

[0peiler]

The result is quite impressive to be honest. Thank you very much for that work!
Now I need to figure out how I can get this code into Staxrip

[SaurusX]

Use a function that resizes but keeps the frame size. Call it with Animate().
....

Great idea there, jagabo. Saved for later use.

[jagabo]

Use a function that resizes but keeps the frame size. Call it with Animate().
....

Great idea there, jagabo. Saved for later use.

Yes, Animate() is a great tool for quickly finding the correct value to use with many filters.

[kenator18]

Sorry for bumping old threads, but THANKS! This method works very well!

[ajent_a]

Use a function that resizes but keeps the frame size. Call it with Animate().
....

Great idea there, jagabo. Saved for later use.

Yes, Animate() is a great tool for quickly finding the correct value to use with many filters.

Hi All
Sorry I'm a complete noob in this field. I have used ffmpeg but not familiar with how this tool works. Here are some questions I need help with:
What is animate()?
How do I install it?
How/on what do I run the above scripts on?

I am really impressed with your result and need to try it out on some of my own.

[jagabo]

Animate() is a built in AviSynth function: http://avisynth.nl/index.php/Animate

See the sample script in post #11.