Virtualdub batch job changes filter settings back to default. Bug?

[gll99]

The short story:

I have many vieos to fix so I set 2 filters in virtualdub and virtualdubmod .

The first filter is the Field reorder which defaults A to B (bottom field first) and the second is Reverse Field dominance which has no settings.

The problem is the Field reorder filter which I need to set B to A (Top field first). If I run the conversion in immediate mode the conversion works fine but if I run it in batch job mode the filter is reset to the default A to B option.

I tested this with mutiple videos and versions (the older mpeg2 version 1.6.19, v 1.5.10 and up to newer v1.91 and they perform the same).

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The long version:

Last summer i built a new pc. The one is my specs was just too slow to do a good job. Now I can capture divx 6.xx 720x480 or 640x480 interlaced video with "Insane Quality" and my processor stays under 75%.

I wanted to put it though its paces so I set the tv box to a station that plays non stop movies of mainly 1930 to 1950 vintage. In my haste, I made one little (big) mistake.... I forgot to set the top field first check mark in the divx codec options and captured bottom field first.

So of course all the clips have side jitter when played on an sd NTSC tv. These files stayed on my computer until just recently when I tried many filters to correct my error and came up with 2 combinations that work. The "Field Delay" filter followed by either the "Field reorder set B to A" or the "Field Dominance" filter. I tested short clips and also did a couple of full films in immediate mode. The fastest combination seemed to be the The "Field Delay" filter followed by the "Field reorder (set B to A)".

I narrowed down the videos I wanted to watch to about 15+, mostly old westerns and war time films and set up a batch encode making sure the "Field Reorder" was properly set "B to A" and started the batch process while I slept, etc... After the process I deleted the original files and copied 4 movies to a DVD/RW disc. As expected the recompress introduced more artifacts but to my horror the jitter was still there and I had deleted the originals. I expected the noise but not the jitter.

I thought I had made another mistake but further testing makes me think it's a bug in vdub. If I had used the other conversion option which was The "Field Delay" filter followed by the "Field Dominance" filter the problem would not have shown up because the default option for the "Field Delay" is "Delay Bottom Field" which happens to be the one I was using and also because the second filter needs no option but for a small speed gain, I used the "Field Reorder" as the second one and that one defaults "A to B Convert to Bottom Field First" and I need "B to A Convert to Top Field First". When I set that option and then sent it to the job queue it reverted to the default option. The proof is 3 fold: First, after conversion, the field order is obviously still wrong on playback and second when I "Abort" the task and recheck the filter selection it's reset to default even though it was properly set when I started the task. Third when I test either a short clip or a complete video by running it immediately (non batch mode) using the same filters the file has no jitter. Of course now without the originals even more noise is apparent but I'm not concerned about that these are not keepers I just want to watch them once. The problem is that it's more time consuming when I can't use batch processing and I'm not sure if this is a vdub or filter specific problem.

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Anyone else have issues with other filters not working properly in batch mode?

[jagabo]

Use Crop to remove one scanline from the top of the frame. Then use the Resize filter to add one scanline to the bottom of the frame (letterbox and resize section). Field order reversed! Since these filters are built into Virtualdub they should work properly in batch mode.

Actually, if you're going to reencode why to you need to change the field order of the frames? Just reencode in fast recompress mode with Divx set to the opposite field order. Maybe your player only supports one field order? I find this is often the case -- because players often don't support interlaced Divx at all. It's just that they have to send one field at a time over the analog cable and use one particular field order when doing so.

I wonder if there's a program that can patch the field order flag within the existing Divx encoded files?

In my experience with Divx anything over Better Quality is pretty much a waste of time (or when capturing, CPU power).

[gll99]

Use Crop to remove one scanline from the top of the frame. Then use the Resize filter to add one scanline to the bottom of the frame (letterbox and resize section). Field order reversed! Since these filters are built into Virtualdub they should work properly in batch mode.

Actually, if you're going to reencode why to you need to change the field order of the frames? Just reencode in fast recompress mode with Divx set to the opposite field order. Maybe your player only supports one field order? I find this is often the case -- because players often don't support interlaced Divx at all. It's just that they have to send one field at a time over the analog cable and use one particular field order when doing so.

I wonder if there's a program that can patch the field order flag within the existing Divx encoded files?

In my experience with Divx anything over Better Quality is pretty much a waste of time (or when capturing, CPU power).

I hadn't posted this but I tried the crop and resize trick early on but it didn't work. In case I messed up, I tried it again but unfortunately with the same result.

I had high hopes for the fast recompress while reversing the field order in the divx codec idea. It was a good one with the least artifacts but sadly it didn't solve the problem.

I'm far from an expert on this but it seems that 2 things have to happen to set things right and I hit the combination purely through trial and error.

After posting, I tried another option which seems to work in batch mode. It's based on the original way I was going to convert the files with one change:

When I first converted the original files, I used the "Field Delay" filter with the option "Delay Bottom Field" and then used the "Field Reorder set B to A".

Since the "Field Reorder" is not applied properly in batch mode I decided to test again using the "Field Dominance" filter which I intended to use at first but found to be a bit slower.

I had to change the setting of the "Field Delay" to get the result I wanted. Normally this would be the wrong setting but in this case with these mixed up converted files, it works.

The filters I am using now are:

The "Field Delay" filter with the option "Delay Top Field" followed by
the "Field Dominance" filter.

I tried a small batch encode on 3 partial files and the "Field Delay" filter kept the option the way I set it.

I am running batch encodes on full files now and should have results overnight.

btw) Previous to this I tried all kinds of single filter tests and none worked until I used 2 filters. I don't know why it works , only that it does.

The "Insane quality" is probably a misnomer. I think it just compresses more so you end up with a smaller file.

[jagabo]

The "Insane quality" is probably a misnomer. I think it just compresses more so you end up with a smaller file.

It's not a misnomer. Yes, it allows for wider searches for motion vectors and can give better compression -- in theory. But in reality the additional compression you get over Better Quality is minimal (like 1 percent). And paradoxically it sometimes it gives less compression. Either way, it's not worth the time or CPU power.

[gll99]

For me to pretend I have in-depth knowledge in this area would only make me look foolish.

I have been capturing and encoding video of many years but never tried to understand the hows and whys i just see what others are doing, do some of my own hunt and peck and then look at the results and choose what I like. It's entirely subjective according to my personal taste.

When it comes to video capture my preference is 720x480 or 640x480 interlaced and as much bitrate as seems reasonable for the material. Since acquiring a fast enough pc to capture from sd source tv at the top divx 6.xx pro quality settings I found that I could reduce the bitrate and still produce video that is quite good with 2 hours or less of capture generating a file somewhere around 900mb to 1.2gb. I've tried it with noise reduction and without. If I could capture the identical program using different settings I might be able to see how much better different settings are but unfortunately with live broadcasts you get one chance to capture the exact same program on the same channel so precise comparisons are hard to do. Overall my poor man's pvr works pretty well. I'm not too hard to please. With rare exceptions, it's just to timeshift my shows so I can watch them on my own schedule.

When the hockey season/playoffs are over and I have free time, I should run a few tests at various quality settings, although this probably means a lot less for real time captures. Since buying standalone divx players, I rarely do any post processing anymore. This was a rare exception due to my mistake.

[gll99]

Update:
gll99 wrote

The filters I am using now are:
The "Field Delay" filter with the option "Delay Top Field" followed by
the "Field Dominance" filter.

That combination works fine in batch mode and although the "Field Delay" filter with the option "Delay Top Field" is not the default it didn't get messed up by the batch encode.

I can only conclude that there is a problem with the "Field Reorder" filter when used in batch mode which falls back to the default setting no matter how it's set.
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To anyone who finds this during a search and gets confused by my options you need to know I was trying to correct a wrong field order but failed to do it properly the first time and deleted the originals so the new 2nd generation inputs are further messed up.

Normally if you capture from a tv tuner NTSC source with the wrong field order (bottom instead of top) then want to correct the error you need to fully reprocess the files using the vdub filters as follows:
The "Field Delay" filter with the selected option "Delay Bottom Field" followed by the "Field Dominance" filter.

Other filter combinations might do the job also but for me, this worked best in batch mode.