interlacing question

[rakan]

I was reading the definition of hard telecine and it says that the frame pattern is progressive, progressive, interlaced, interlaced, progressive or 3:2. However, I have a anime DVD where the pattern is progressive, progressive, progressive, interlaced, progressive or 4:1. Is my DVD hard telecined?

[jagabo]

Hard telecine doesn't have to have the 3:2 pattern. Other patterns are possible -- your 4:1 being one of them. Either way, this is not conclusive evidence that your source is hard telecined. Some programs display the video after performing the soft telecine pulldown -- so soft telecined material will show interlaced frames. What software did you use?

[rakan]

Hard telecine doesn't have to have the 3:2 pattern. Other patterns are possible -- your 4:1 being one of them. Either way, this is not conclusive evidence that your source is hard telecined. Some programs display the video after performing the soft telecine pulldown -- so soft telecined material will show interlaced frames. What software did you use?

Thanks for the reply jagabo. I opened this video by making a .d2v file using dgindex and opening that in megui's avsscript creator (which I guess would be avisynth). I then stepped through the frames one at a time and noticed that the pattern was 4:1. Was this the proper way to detect the interlaced pattern?

[jagabo]

What Field Operation setting did you use in DgIndex? Honor Pulldown Flags will perform the pulldown so that you see comb artifacts -- but this is the only setting that will keep A/V sync with variable frame rate soures. Ignore Pulldown Flags ingnores pulldown flags (like VirtualDubMod) but may leave you with the wrong frame rate. You can fix it with an AssumeFPS() unless the frame rate is variable. Forced Film will work with 23.976 fps sources with pulldown flags. It won't work with other frame rates or variable frame rates.

[rakan]

What Field Operation setting did you use in DgIndex?

I checked and the "Honor Pulldown Flags" option was on. I remade the project with the "Ignore Pulldown Flags" option checked and I see the same pattern, four progressive frames and then one interlaced frame. I guess this means my source is hard telecined using 4:1, right?

[jagabo]

I remade the project with the "Ignore Pulldown Flags" option checked and I see the same pattern, four progressive frames and then one interlaced frame. I guess this means my source is hard telecined using 4:1, right?

Yes. The pulldown pattern is 2:3:3:2. Commonly used with 24p DV.

[rakan]

Thanks again for the help. One more question...

My goal is to deinterlace and convert the framerate to 24 pfs. It appears that the interlaced frames are a composite of the two progressive frames on either side of it. It occurred to me, the easiest way to deinterlace would be to delete every fifth frame (in other words, delete the interlaced frames). This would result in 24fps and no interlaced frames, right?

[jagabo]

Yes, just throw out the interlaced frames. That's why that pulldown pattern is used with 24p DV -- the processing is simpler.

[manono]

1. If for NTSC, don't ever use Ignore Pulldown Flags. It's almost a recipe for audio desynch. If there are any soft telecined portions at all, you're screwed. If it's anything but 100% Progressive Film, use Honor Pulldown Flags as it's much safer. In the DGIndex Manual, neuron2 says this about using Ignore Pulldown Flags:

If the pulldown is irregular, use of this option will cause the audio-video sync to change at different parts of the clip, and most likely sync will not be acceptable.

2. If trying to pull out every 5th frame with something like SelectEvery(5,0,1,2,3), with any break in the cadence you're screwed. With anime you get all the repeated frames which might seem to give a 4:1 pattern. Me, I'd still use a regular IVTC, but you can check first to see if the pattern is consistent throughout the video. Theoretically, pulling out every 5th frame might lead to better results, and the encoding will go a bit faster, but it can be pretty risky.

[rakan]

manono and jagabo

Thank you for the information. I will use "Honor Pulldown Flags" in the future. My original question was geared toward better understanding hard telecine patterns and also determining how to truly determine the interlaced pattern of my DVD source.

I did write a avisynth script that skipped every 5th (interlaced frame) and, just like manono said, there were parts of the video that had inconsistent patterns of interlacing (on occasion there was a interlaced frame every 4th frame). I went back to using animeIVTC(mode=1, aa=0) and everything has been fine so far. Thanks again