[FFmpeg-user] Creating interlaced DV AVI material from a frame sequence

[Thomas Mechau]

Hello,

I have kind of a legacy problem:

Several years ago I had some Super 8 cine material transferred 
professionally to miniDV cassettes. I then imported that DV video as 
native PAL DV AVI files, i.e. 50i video with a resolution of 720x576 
(non-square) pixels.

Since one section of the footage contained a lot of critical dust 
specks, I needed to remove them by retouching picture by picture. The 
stills exported from Premiere PRO are de-interlaced (as is the Premiere 
single-frame preview), but often the dust specks affect two fields on 
adjacent frames, so even if the problem seems fixed in the preview after 
importing a retouched still, it is nevertheless visible during playback 
when that field which was hidden by the deinterlacing becomes part of 
the interlaced stream again.

Therefore I tried to find a way to extract the individual fields and 
retouch them.

The following two ffmpeg commands did the trick:

ffmpeg -i ProblemFile.avi -vf field=top Top\ProblemFile_%05d.png    
ProblemFileAudio.wav
ffmpeg -i ProblemFile.avi -vf field=bottom Bottom\ProblemFile_%05d.png

This creates one audio file and two sets of sequentially numbered PNG 
images in the folders Top and Bottom. I can then use Advanced Renamer to 
adapt the start numbers and the number step of the two sets (00000, 
00002, 00004, ...; 00001, 00003, 00005, ...) so that a new folder Merged 
contains one sinlge set of contiguously numbered images, which are 288 
pixels high and represent the individual fields of the DV frames, i.e. 
have half the frame rate of the original video.

I can then load the required frames into an image editor like Photoshop 
to retouch the dust specks (a tedious job).

So far, so good. My problem is now that the set of updated PNG images 
needs to be converted back to an interlaced AVI video file.

After much research and experimentation I found that the following 
command delivers a useable video file(50i plus sound):

ffmpeg -i ProblemFileAudio.wav -i Merged\ProblemFileFixed_%05d.png -vf 
tinterlace=0 -aspect 4/3 ProblemFileFixed.dv

However, the result is a QuickTime file, and I need a DV-PAL AVI file 
for my workflow.

Any ideas how this can be achieved, possibly in just one step?

Many Thanks!

Thomas