VirtualDub Saving Takes Ages

[Bollocks]

So, with PAL footage I should just deinterlace, not use IVTC at all, and work with the footage at 25fps?

[Qyot27]

Yes.

The thing is, there's 'deinterlacing' which often means either 'Vertical Blur' or 'Bob' the footage (the first preserving 25fps, the second doubling it to 50fps), and 'field matching' (which keeps 25fps). Field matching is the first step of IVTC, and it can be used on PAL footage. It's the decimation step of IVTC that you don't use with PAL.

[Bollocks]

Sorry to have left this so long, but what's the recommended method for deinterlacing PAL footage? I've just used TDeint again, which seems to have worked fine, in that it worked and the fps is the still 25, but I'm aware that there is likely a more suitable method.

[Qyot27]

TFM can be used (with TDeint as illustrated before to pick up the remaining combed frames that TFM lets pass through), and so can Telecide (the documentation of which explicitly talks about using Telecide(order=1,guide=2) for progressive PAL content/2:2 pulldown). TFM and Telecide only reconstruct - or try to reconstruct to the best of their ability - the original frames, they don't mess with the framerate. The reason that 29.97fps NTSC content that's passed through an IVTC comes out at 23.976 is because the decimation filter tries to find the extraneous duplicates in the stream that are a side effect of making 24fps Film content into 30fps for television broadcast, and it then removes them, altering the framerate (this is why using a decimation filter on PAL content results in that 20fps rate seen earlier).

The significant difference from typical NTSC inverse telecine prodcedure is that for PAL content, you don't use the decimation filter. You would stop after the TFM or Telecide step.