There have been many that asked how can they deinterlace the video in TVAI using Dione:DV, Dione:TV or Iris without doubling (bobbing) the frame rate.
By default if you select Interlace in TVAI it would automatically select x2 on the FPS. e.g. if your video is Interlaced 25fps, the output would become 50fps.
Even though most claim that it is a good practice to bob (double) the fps for motion smoothness it doesn’t come without its own issues.
for example: each frame has half the vertical resolution, or resolution equal to that of each field that the frame was made from. Bobbing prevents combing artifacts and maintains smooth motion but can cause a noticeable reduction in picture quality from the loss of vertical resolution and visual anomalies whereby stationary objects can appear to bob up and down (hence, the name “bobbing”) as the odd and even lines alternate.
Many requested how can they Deinterlace but keep the original fps without bobbing.
TVAI documentation sais that for one to keep the original fps, one must select manually the fps he/she wishes to have.
the problem with this method is that it requires you to turn on frame interpolation for this to actual work, if not it just won’t work and you would still have the double frame rate even though you selected “25fps” manually as in the example.
There are two problems with this out of the box method.
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you are artificially doing a frame interpolation (using TVAI filter) that is not needed. this may reduce quality and some picture distortion as we all know the frame interpolation is not perfect.
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You adding extra workload on the TVAI video process as now TVAI needs to process two filters instead of one, and that costs time. in other words, you are going to wait more time to finish processing your video.
Turns out TVAI does no deinterlacing. TVAI instead uses the bwdif filter from ffmpeg to do the deinterlacing.
So why not utilize it’s, i.e. FFmpeg, function and tell it not to bob the video? As this is supported OOB by FFmpeg. 
That is what we going to do now.
The method that I found that works very well, is by utilizing FFmpeg’s built-in function to retain the original fps. It would be much quicker to process and would not introduce any artifacts that frame interpolation potentially does.
here are the steps:
- load your video into TVAI and set all your settings for deinterlacing , upscale, whatever you want, as you Ready to press the “Export” button.
Example:
- press Ctrl+Shit+E, this would open a window with the command that TVAI would run in the background in case you would press the “Export” button.
Copy the content by clicking on the “Copy” Button.
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Open Notepad and paste the content you just copied into notepad
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In Notepad, search for
bwdif=mode=1and replace the “1” with a “0”. leave the rest untouched. -
Copy everything from notepad (Ctrl+C).
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In TVAI press Ctrl+T, this should open a command prompt. paste the content you just copied from notepad into the command line and Press “Enter”.
Example:
That’s it, your video will now be deinterlaced at original fps with the AI you chose (Dione:DV / TV, Iris).
no frame interpolation , much faster process and natively supported by ffmpeg.
I wish Topaz would just have this function in the UI as a drop down option when deinterlacing (to x2 fps or not) and based on the selection change the FFmpeg command line. it is so simple to implement. hardly any coding is needed.
