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Realities of Standards Conversion (in this case PAL to NTSC)

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Scott Bush
Realities of Standards Conversion (in this case PAL to NTSC)
on May 25, 2011 at 5:38:55 pm

Hello,

I somewhat regularly get requests to convert files (TV Commercials) from one format to another. Currently I am working with a PAL spot that needs to be subtitled and converted to NTSC. The source is an IMX50 file, SD PAL (4:3). I am using Episode Pro 6.1.0.4

From poking around I found that I could (and should) use a modified version of the preset "StdConv Interlaced to PAL" set to use my encoder etc. Problem is, when I do this, the client is not pleased with the quality of the result. It displays common de-interlacing artifacts like jagged edges on packs and logos, and some "crawling" in text and supers. Overall the image is ok, but when dealing with a brand the logos and packs are what they focus on.

(For the record, I've tried to get them to use the PAL original to no avail).

Looking at the preset, I see that it is doing a deinterlace, then "advanced frame rate" conversion, then resize, then a re-interlace.

Is there anything I can do to minimize the artifacts I am getting, or is this just inherent to these types of conversions? I feel like I've seen better conversions done elsewhere, but I have no idea what hard- or software they may have used.

Are there better ways to do this? Please advise.

Thanks,
Scott


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Craig Seeman
Re: Realities of Standards Conversion (in this case PAL to NTSC)
on May 25, 2011 at 6:11:23 pm

[Scott Bush] "StdConv Interlaced to PAL"
If you're going from PAL to NTSC that should be to NTSC.

Episode Deinterlaces so fields become progressive frames. Then the frames are converted to the new frame rate in the advanced frame rate filter and then the results are interlaced.

In the Deinterlace filter you may need to change detection from Automatic to the specific field dominance if Episode guesses wrong. Test to see if that improves things. The next step in that filter would be to change create new fields by Motion Compensation to something else although that's usually the best, there may be exceptions. You may want to use something other than the DV codec that template defaults to.


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Scott Bush
Re: Realities of Standards Conversion (in this case PAL to NTSC)
on May 25, 2011 at 6:52:15 pm

Ha yeah thanks - major typo... I understand how it all works, just wondering if the quality hit I am experiencing is normal. I will try the settings you suggest.

How perfect should a PAL to NTSC (or vice versa) be? What is realistic?



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Craig Seeman
Re: Realities of Standards Conversion (in this case PAL to NTSC)
on May 25, 2011 at 6:55:42 pm

[Scott Bush] "How perfect should a PAL to NTSC (or vice versa) be? What is realistic?"

The other day someone was praising what a great job Episode does with standards conversions. It may depend on content. I don't think you should be seeing interlacing issues though. Field order on the interlace filter might make a difference too depending on how the file is being played back. Of course on a computer interlaced video doesn't look good.



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Scott Bush
Re: Realities of Standards Conversion (in this case PAL to NTSC)
on May 25, 2011 at 7:04:52 pm

Well now I'm having a sudden new issue where Episode won't convert my ProResHQ file... was working before but now I get a failed error with "no importer found" -- time to reboot.



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Craig Seeman
Re: Realities of Standards Conversion (in this case PAL to NTSC)
on May 25, 2011 at 7:18:52 pm

That would mean it can't find the codec.
Try rebooting the computer. Also try creating a new user with admin status and trying from that account and see if that impacts it.



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Scott Bush
Re: Realities of Standards Conversion (in this case PAL to NTSC)
on May 25, 2011 at 7:26:28 pm

This is very odd indeed. Just earlier today the SAME file was working. I rebooted and still nothing. Tried to make a ProRes 4444 and same error... but with a clip rendered in 'Animation' it works fine. Why would it all of a sudden lose track of ProRes encoder? I use ProRes all the time!

Anyway, I got the NTSC file to look a bit better by forcing it to top field first. I still see some jagged edges on supers (and other small, hard edged objects) - especially if the background is moving (these are the deinterlacing artifacts I mentioned earlier and I've yet to find a way to completely eliminate them when doing any sort of deinterlacing. I see them on a computer - even when deinterlacing playback - and an NTSC monitor. I think it comes from interpolating new fields) but this should be acceptable.



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Craig Seeman
Re: Realities of Standards Conversion (in this case PAL to NTSC)
on May 25, 2011 at 10:43:52 pm

[Scott Bush] "tried to make a ProRes 4444 and same error"

ProRes 4444 may not work although I'd need to double check that.

Something though has impacted Episode's access to the ProRes codec. Let me know if it's still failing. Try using ProRes source as well as attempting an encode to ProRes.



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Robert Longwell
Re: Realities of Standards Conversion (in this case PAL to NTSC)
on May 26, 2011 at 3:29:04 pm

Scott,

Try other de-interlace settings that only look for moving areas to de-interlace. That can help significantly with static items like logos or lower thirds.

Robert Longwell


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