njahnke
13th July 2006, 11:50
apologies in advance if this is common knowledge here. i really need to start frequenting this forum given that digital video is now like my entire life.
the gamecube (and by extension the game boy player) employs a kind of deflicker to its output. there is actually a toggle for this in the smash bros melee options, though i can't think off the top of my head what they called it. you would know it if you saw it though - it does a great job of cutting down on the flicker on an analog tv, but unfortunately it's a portal to hell for capturing the game ...
my understanding of how it works is sketchy, but i know that splitting the fields of resulting video (and therefore doubling the framerate) results in video whose every other frame is one half pixel different vertically than the previous. clearly, you can't move things distances of less than a pixel without making things rather unclear, and so i tend to refer to what this thing does as "blurring the even field". perhaps that's how it works - thin horizontal lines that would normally flicker are blurred, but the image still seems quite sharp, because it's only one field that's been blurred.
anyway, i've dealt with this in a variety of ways over the years, each (hopefully) better than the last, but now i'm becoming much more proficient in avisynth, and i've gotten the picture to a point where the difference between every other frame is obvious (even after being mutilated by vhs, the even field is significantly fuzzier than the odd).
i was able to put the fields back on top of each other vertically (this is only a half resolution source) by actually using LeakKernelBob() with a threshold of 0, then separating the fields, so (i use a dvd recorder to capture):
AC3source(MPEG2source("C:\aj\aj.d2v"),"C:\aj\aj.ac3").converttorgb32
Lanczos4Resize(640,480) #comes in 720x480 so needs aspect ratio correction
LeakKernelBob(order=1,threshold=0,sharp=true,map=false)
Crop(86,78,-90,-82) #game boy player border
separatefields
changefps(59.94) #framerate is now 2x too fast due to deint + field sep
here are some pics i took that illustrate the blurring problem pretty well i think: even (http://nate.quandra.org/aj-even.PNG) odd (http://nate.quandra.org/aj-odd.PNG)
i tried to find a place where things didn't move very much between two frames so the difference would be clear.
okay so, i need to either blur or sharpen one of the fields, right? well, that didn't work out so well:
clip1=selecteven.sharpen(0.5,0)
clip2=selectodd.sharpen(0,0)
interleave(clip1,clip2)
something like that will work, but it doesn't reproduce the blur from the gamecube very well, and it's still brutally obvious that the adjacent frames aren't buddies, and i don't even want to think about what that does to the compression.
so, does anyone have any thoughts? i'm open to completely changing how i process game boy player video, but i suspect just a simple filter or two will do the trick - i just need recommendations on which ones. i process video like this not only from vhs sources, but from good dvd sources recorded with s-video, also, so solutions for either or both types of source would be great.
thanks in advance.
the gamecube (and by extension the game boy player) employs a kind of deflicker to its output. there is actually a toggle for this in the smash bros melee options, though i can't think off the top of my head what they called it. you would know it if you saw it though - it does a great job of cutting down on the flicker on an analog tv, but unfortunately it's a portal to hell for capturing the game ...
my understanding of how it works is sketchy, but i know that splitting the fields of resulting video (and therefore doubling the framerate) results in video whose every other frame is one half pixel different vertically than the previous. clearly, you can't move things distances of less than a pixel without making things rather unclear, and so i tend to refer to what this thing does as "blurring the even field". perhaps that's how it works - thin horizontal lines that would normally flicker are blurred, but the image still seems quite sharp, because it's only one field that's been blurred.
anyway, i've dealt with this in a variety of ways over the years, each (hopefully) better than the last, but now i'm becoming much more proficient in avisynth, and i've gotten the picture to a point where the difference between every other frame is obvious (even after being mutilated by vhs, the even field is significantly fuzzier than the odd).
i was able to put the fields back on top of each other vertically (this is only a half resolution source) by actually using LeakKernelBob() with a threshold of 0, then separating the fields, so (i use a dvd recorder to capture):
AC3source(MPEG2source("C:\aj\aj.d2v"),"C:\aj\aj.ac3").converttorgb32
Lanczos4Resize(640,480) #comes in 720x480 so needs aspect ratio correction
LeakKernelBob(order=1,threshold=0,sharp=true,map=false)
Crop(86,78,-90,-82) #game boy player border
separatefields
changefps(59.94) #framerate is now 2x too fast due to deint + field sep
here are some pics i took that illustrate the blurring problem pretty well i think: even (http://nate.quandra.org/aj-even.PNG) odd (http://nate.quandra.org/aj-odd.PNG)
i tried to find a place where things didn't move very much between two frames so the difference would be clear.
okay so, i need to either blur or sharpen one of the fields, right? well, that didn't work out so well:
clip1=selecteven.sharpen(0.5,0)
clip2=selectodd.sharpen(0,0)
interleave(clip1,clip2)
something like that will work, but it doesn't reproduce the blur from the gamecube very well, and it's still brutally obvious that the adjacent frames aren't buddies, and i don't even want to think about what that does to the compression.
so, does anyone have any thoughts? i'm open to completely changing how i process game boy player video, but i suspect just a simple filter or two will do the trick - i just need recommendations on which ones. i process video like this not only from vhs sources, but from good dvd sources recorded with s-video, also, so solutions for either or both types of source would be great.
thanks in advance.