Convert 50p to 50i

[jovnas]

I just finished editing a video that had all of its footage shot at 50p and had graphics in 50p. I exported the video and now I realized that the requirement for the video was 50i and not 50p. The video is already done and all of the footage is already shot and I have to submit the video in 2 days so how do I go about converting it to 50i? I think that I can just export the video again in 50i and everything is gonna be fine, but will it? Should I just export it again in 50i or do I have to do something else? Any feedback is appreciated.

[DB83]

You may require some clarity from the client.

These days '50i' could simply mean 25 frames per second interlaced ie 50 fields per second as opposed to an actual 50 frames per second.

[ConsumerDV]

Should I just export it again in 50i or do I have to do something else? Any feedback is appreciated.

Yep, just export as 50i. What you've done is you have followed the EBU recommendation of future-proofing by mastering in 1080p50 even if the delivery format is 1080i25.

These days '50i' could simply mean 25 frames per second interlaced ie 50 fields per second as opposed to an actual 50 frames per second.

These days as well as those days. Nothing has changed in this regard.

[Cornucopia]

Since there only ever was 2 real framerates that were interlaced (25 & 29.97/30) that have made it to the modern era, it really doesn't make sense to use the terms "50i" or "59.94i/60i", as ALL other framerates are described in reference to frames, while only these 2 reference fields when using the i (and they are equivalent to 25i and 29.97/30i respectively, anyway).

Maybe in the waning years of interlacing we can finally get on the same page to simplify something that has tripped up so many newbies, and drop that alternate nomenclature.


Scott

[jovnas]

Yep, just export as 50i. What you've done is you have followed the EBU recommendation of future-proofing by mastering in 1080p50 even if the delivery format is 1080i25.

Thank you for your help! I exported the video again in 1080i25 and it looks fine.

[Luke M]

Since there only ever was 2 real framerates that were interlaced (25 & 29.97/30) that have made it to the modern era, it really doesn't make sense to use the terms "50i" or "59.94i/60i", as ALL other framerates are described in reference to frames, while only these 2 reference fields when using the i (and they are equivalent to 25i and 29.97/30i respectively, anyway).

Maybe in the waning years of interlacing we can finally get on the same page to simplify something that has tripped up so many newbies, and drop that alternate nomenclature.

I don't know, I can see somebody getting tripped up by 30i, thinking that the output after deinterlacing should be 30p.

[Cornucopia]

That is a possibility, but that is one now as well. Deinterlace output options and methods is its own can of worms. I don't think people are any clearer about what to do just because they see 60i either, and 30p is certainly one of the possible outcomes.


Scott

[DB83]

Yep, just export as 50i. What you've done is you have followed the EBU recommendation of future-proofing by mastering in 1080p50 even if the delivery format is 1080i25.

Thank you for your help! I exported the video again in 1080i25 and it looks fine.

This probably will not, initially, matter right now since you will have delivered your video.


But I can not, basically, get my head around going from 50p (which should be unique frames) to 25i (which should be unique fields)


You can, of course, check this with a player that has de-interlacing turned off and you should then see the fields. However, it may look 'fine' since nothing has actually happened to the video and it is still progressive and simply flagged as interlaced.


(I'll go back to my cave now since I am possibly having a 'senior' moment)

[Cornucopia]

@DB83, If you've got 50p and you are going to 25i, you would merely alternately strip the odd fields from one frame and even fields from the next (or vice-versa, depending on field dominance needs). This is in essence what an interlacing camera would be doing upon seeing a real-world image. There is some minor difference due to what I would describe as interline changes, but that difference would be mitigated with high shutter rate - aka small shutter angle - shooting (which lots of cameras can do).

I agree, ALWAYS keep the best master possible for reference & archiving, and in this case that would be a 50p version.

Scott