Quantcast How to check frame order in captured file? - digitalFAQ Forum
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06-28-2022, 05:05 PM
BruceOlsen BruceOlsen is offline
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I'm picking up my home video conversion project post-pandemic and I've forgotten a lot in the interim.

Captures are done and I'm about to start serious editing and I've become concerned about the format of the captured files.

All the original captures were made with VirtualDub encoded with HuffYUV. Then the unwanted parts were trimmed away, with the remainder saved in another file compressed with Lagarith. This work was actually done by a very non-tech person so we used our NLE (Corel VideoStudio) to do the trimming instead of avisynth. All the files play fine.

I thought I followed the capture instructions pretty carefully, and It's my understanding that the files should have been captured upper frame first, but our NLE seems to be claiming that the files are lower frame first (the doc is pretty superficial so I can't be sure what it's actually reporting on).

So how can I check that my captures and my trimmed copies are formatted correctly? Mediainfo doesn't seem to report on which frame is first and I don't trust the NLE at this point.

Thanks.
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06-28-2022, 07:48 PM
Hushpower Hushpower is offline
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Open a file in VDub. These instructions are for VDub2.

Video>Filters>Add

Choose the "deinterlace" filter and click OK.

On the right, set the Field Order to "Double Frame Rate Bottom Field First" then OK, OK.

Leave the left selection on "Interpolate using Yadif".

Now, step through areas of movement. If you've got the field order wrong, you'll see movement do the two steps forward, one step back thing. That means that the field order you've selected for the deinterlace is wrong.

Go back to the deinterlace filter and set the other field setting and step through again. You should get video that moves only in the correct direction with no frames/movement reversing. That will be the correct field order.

Don't forget to delete the deinterlace filter!

FYI, all my captures are TFF.

I believe Mediainfo doesn't report the field order because the info isn't written into the file when it is created by the capture program.

Last edited by Hushpower; 06-28-2022 at 07:53 PM. Reason: "VDub2" added.
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  #3  
06-28-2022, 07:50 PM
keaton keaton is offline
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Their is no field order information stored in the lossless AVI files, so no program would show you this. If you had compressed it to an interlaced format such as MPEG2, you could find that information in some programs. I think GSpot is a tool I've got from this forum. Gspot Codec Analysis Tool - AVI codec info [DOWNLOAD]

Sanlyn's post here Determining field order of captured HuffYUV AVI? is a nice quick way to find out (assuming you've got Virtualdub installed) with the deinterlace filter. That filter should come with if you got the 1.9.11 Virtualdub pack available for download from this forum.

As mentioned here, if you go to Filters on the Video menu and add the deinterlace filter then select it and click Configure, select Deinterlace mode of Interpolate using Yadif and select Double frame rate, top field first in the Field order list, then click Ok and Ok again from the Filters menu, then advance one frame at a time in virtualdub (using left/right arrow keys). If you see a stutter of forward and backward movement in the right hand window (left window shows original video, right window shows video with Filters applied), then the field order is bottom field first. If it all frames are moving forward with no backward stutter, then it is top field first. If it stutters, you can reconfigure the filter with bottom field first to verify that you see no stutters. That would confirm it is bottom field first.

Another way I do this is with Avisynth, if you have it. A AssumeTFF() function call followed by a SeparateFields() function call in an avs script will show the fields. If you see the stutter, then the fields are bottom first. Same idea, different method to see the field order.
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06-28-2022, 11:31 PM
BruceOlsen BruceOlsen is offline
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Thanks a lot. I'll give that a try tomorrow.

I have both VDub and avisynth. Knew them fairly well a couple of years ago...

I'll probably use both just to exercise the muscles and post results.
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