Captured subtitles have horrible artifacting

[kempodragon]

Recently I did a capture of a subtitle movie. As I mentioned in an earlier post, I can only cap at 720x240, 59.94fps now. In the raw capture, the subtitles are crisp and readable. However, when I weave the frames together, certain sections of the movie's subtitles have such horrible artifacting that they are almost unreadable. The problem is that it only occurs randomly and not throughout the picture. The problem is visible even when I use MPC to output the avs to my TV Here are examples of both good and bad subtitles, with the woven and unwoven frames.


6221

6222

6224

6225

6226

All the pictures have not had any filtering done. Please help me figure out what going on.

[Wilbert]

If you replace your pngs by jpegs i will approve them.

[kempodragon]

I've redone them as jpegs, the original pngs of the others were just too big. I didn't want to use Jpeg, since I was afraid that it would create artifacting on top of what I wanted to show, and thus confuse the issue. The capture file is Huffyuv, so I'm not sure what to do if you want the to test the original. BTW, here is my script:

AviSource("G:\Capture.avi")
Trim(38241,464107)
AssumeFieldBased
Weave
#Info

[foxyshadis]

So what sort of artifacts are you seeing? I see some noise (likely jpeg's fault) and some combing, but nothing out of the ordinary. Is it the combing? You'll need a deinterlacer that can handle that without munging the subtitles horribly, which tdeint or securebob can do. Or if you're going to put it on a DVD, it can just be encoded interlaced.

[kempodragon]

The problem is the second scene. If you look at the subtitles before weaving, there is no noise of any kind. Weave them together, and you get exactly what you see. This is not from compressing them, it is what I get when opening the avs. I outputted the avs to my TV, and got the same problem. When I captured the movie, the subtitles appeared as they should be. I don't think it's interlacing, because I stepped through the scene and the subtitle appear the same on both interlaced and non-interlaced frames.

[scharfis_brain]

delete the first frame, or apply the swap fields filter.

what kind of capture device do you have?

I never heard of the possibility to be able to capture in 59.94 fps at field height only....

[kempodragon]

I have an ATI AIW 9800 Pro. Originally, I could cap at 720x480, 29.97 but when I upgraded my drivers a while back, for some reason I was locked into this way for avi files. Capturing in MMC results in horrible frame droppping, and the drivers outright refuse to support in Vdub, even under custom settings. During capturing, my CPU usage runs about 25-30%, so I never really thought about it. BTW, this happened once before on another subtitled movie, but because that picture had other problems, I put it down to a bad capture.

Just tried swap fields and now the problem is reversed!! Scene 1 has bad subtitles and scene 2 has good subtitles. I'll try deleting the first frame later and see what happens

[Mug Funky]

try this (with masktools v2):

function autoswap (clip c)
{
global order = c.getparity()==true? 1:0
global as_c = c
d=c.converttoyv12().horizontalreduceby2()
global swapped = c.swapfields().doubleweave().selectodd()
global cmetric = d.mt_edge("-1 -2 -1 2 4 2 -1 -2 -1 16",0,255)
global smetric = d.swapfields().mt_edge("-1 -2 -1 2 4 2 -1 -2 -1 16",0,255)

scriptclip(c,"cmetric.averageluma > smetric.averageluma? swapped : as_c")
}

then call it as "autoswap()" in your script.

you can get away with the above because it's a 3:2 film. but i'm not sure how this will affect IVTC later on (it'll probably be fine).

btw, which Zatoichi film is this? there's a few to choose from, though not many in colour.

[kempodragon]

It is "Zatoichi: The Lone Swordsmen", the last Zatoichi film and one of Shintaro Katsu's last films before his death. I captured it off Showtime Extreme, as it is one of the regularly cycled films in the lineup. I don't have masked tools, so I'll have to download it and try it out this weekend.

[scharfis_brain]

why did you ignore my post?

my solution is very easy to apply if this error is throughout the whole movie.

[Mug Funky]

probably the most useful solution is to fix the capture setup somehow :)

maybe it's dropping a single field, and that's putting the rest of the movie out of order (because tops become bottoms, and when they're weaved it's all misaligned).

in which case some kind of automated drop detector would be useful, but i haven't a clue how it'd work (maybe check the first picture line isn't offset from the previous top/bottom field? easier said than done).

either way, the US DVD for this is available, and the quality on that easily surpasses the broadcast you're capping (as does the R4 version, nudge-nudge). i think it's released through AnimEigo, IIRC.