I’ve exported a PNG sequence from Synfig Studio at 50 frames per second.

I need to create a PAL video at 50 fields per second.

What I want to do is to create an interlaced video so that each frame contains two fields, one from one frame of my original video and one from the next.

Does anyone know how to get FFMPEG to interlace a 50fps PNG sequence?

EDIT: I’ve worked out how to do this using Avidemux. Export the video at 50fps and half height from Synfig Studio, then use the Interlacing -> Merge Fields filter in Avidemux.

If Avidemux works, why bother with ffmpeg?

Well, I’ve just discovered Avidemux doesn’t actually work! It’s really interesting how hard this is to do properly.

If you do interlacing in Avidemux it does horrible smoothing of your graphics - you have to use Bilinear to composite the images together, you can’t use None.

I used to do this in VirtualDub - I might have to go back to that if I can’t find a way to do it in FFMPEG as I really need 50fps interlaced animation for something.

I thought 50 fields is usually 25 frames, not 50 frames? i.e. odd then even lines of the same frame (or vice versa). You’ll get some horrible artifacts if you’re doing different frames in adjacent fields- or is that the aim?


Yep, that’s the aim! I’ve got to recreate the output of an old piece of graphics hardware :laughing: