digitalFAQ.com Forum - Bad stuff that novices and pros don't expect

More Bad Tape Chronicles
Film Damage and Flood of Spots & Dropouts.

The source VHS is a very bad retail digital remaster (an amateur could get a cleaner encode, IMO). Has a ton of compression artifacts and fine detail loss from bitrate starvation, and tape noise. Playback for capture was with a rebuilt Panasonic AG-1980 + AVT-8710 + PA-100 proc amp + AIW 9600XT AGP into Virtualdub/huffyuv YUy2 in XP/Sp3. The AVT-8710 is an original 2004 greenie, still going strong. Post processing was with lossless Lagarith on a Win7 PC and Avisynth/VirtualDub.

There isn't enough forum space to go into detail on the slew of problems in this brand-new VHS tape. The dropouts, spots, and film damage took up enough time and effort by themselves. There were literally hundreds of bad frames requiring work. The attached "bad_cuts.mp4" shows about 18 short bad shots. The attached "Fixed_cuts.mpg" plays the same frames after cleanup.

- Bad cuts.mp4 is interlaced with hard telecine, from the original lossless capture. A copy of the lossless .avi original of sample cuts is at https://www.mediafire.com/file/rfgxg...ginal.avi/file, 272 MB in Lagarith YUY2 at (this is a MediaFire pro account -- no popup ads).

- Fixed_cuts.mpg is progressive with 3:2 pulldown, from the encoded final DVD.

As some TCM fans might know, TCM occasionally broadcasts their own cut of this 1931 movie. After my nightmare viewing of the VHS tape I figured their digital broadcast would look much cleaner. It didn't. It has the same spots, same film damage, same low bitrate artifacts, and even the same off=pitch intro music as the tape.

from original lossless VHS capture. Damage extended over 3 frames:
http://www.digitalfaq.com/forum/atta...1&d=1580096718

from TCM digital broadcast. Damage extended over 3 frames:
http://www.digitalfaq.com/forum/atta...1&d=1580096718

VHS after IVTC and cleanup, from final encoded MPG:

http://www.digitalfaq.com/forum/atta...1&d=1580096718

Cleanup tools used for spots, streaks, cuts, and other physical damage: RemoveSpotsMC.avsi, RemnoveDirtMC.avs, ReplaceFramesMC.avs. Links and usage notes for those filters are in post #64 in the thread at http://www.digitalfaq.com/forum/vide...html#post47776.

Other tools for various denoising and artifact smoothing: MCTemporalDenoise, QTGMC with EZDenoise, DfftTest, GradFun3, LimitedSharpenFaster, and very light touches of VirtualDub's smartsmoother and NeatVideo.

In dozens of cases a special routine was used to clean up spots and other damage when others didn't work. This routine has been described in earlier threads. It creates a "clean patch" in the same size and location as another artifact but from a clean part of another frame, then overlays the clean patch onto the bad frame. A typical sample goes like this:

Code:

  ##-- frame 276, white dot on back of girl's sweater, center.

last=S3 

b0=s3

b01=s3.ReplaceFramesMC(276,1).Crop(396,254,-304,-214) 

b02=Overlay(b0,b01,x=396,y=254) 

s4=ReplaceFramesSimple(s3,b02,mappings="276")

S4

The variable "S3" is created as a copy of the clip from the "last" or preceding processing step.

The Variable "b0" is set equal to S3, so that we can manipulate b0 but S3 will remain unchanged.

The variable "b01" is used to interpolate a new version of frame 276 from clip S3, created from the motion difference between the preceding and following frame. Then Crop() a small square of clean data from the resulting new frame and save it as b01.

Take the small clean patches saved as clip "b01" and overlay them onto all the frames in "b0". Save the result as "b02".

Because we don't want thousands of copies of the overlaid frames in b02, we use ReplaceFramesSimple (part of RemapFrames.dll) to replace a single clean frame 276 from b02 onto a single frame 276 in the original b0. Save the result as clip "S4". S4 can then be used as the new, cleaned clip in further processing.

Similar routines have been used to replace multiple spots or glitches in the same frame.