AssumeXFF().SeparateFields() gives a bobbed stream?

[Chainmax]

I'm trying to know wether a clip is TFF or BFF, but opening a script with only AVISource/DirectShowSource and that line gives me a 59.94fps output. What's going on? I'm using Avisynth v2.56.

[AVIL]

Hi,

If original framerate is 29,97 your result is normal (separatefields convert every frame in two frame, one per field, as is expected). If your play the video and the image is bobbed (with little vertical displacement interframe) but progressive your assumption AssumeTFF or AssumeBFF is the correct one. If playing the video the image is jerky, you have stated the wrong precedence.

[Chainmax]

I know how to detect if the choice is good or bad, but didn't know that separatefields converted each field into a frame :o.

[communist]

There is a difference between a bobbed stream and a stream with separated fields. Bob will interpolate pixels and create a stream with full resolution frames, whereas separatefields will only split the frame into its fields and display them in order. You will get "frames" with half the original resolution or sometimes called "half-frames".

[Chainmax]

I see, thanks for the clarification.