Working with different frame rates

[jcarst85]

Hi there,

I was using my GoPro Hero 4 Silver recently to support a semi-professional videographer (by way of taking some b-roll footage) we had contracted to work on a corporate video for our company. He told me he was shooting at 50i though and that, as my GoPro was progressive only, there could be compatibility issues.

My first question then is, can you successfully merge interlaced and progressive footage? If so, what is the best progressive frame rate I should film in to be compatible with his 50i? Should I just match his frame rate, i.e. 50p to match his 50i? Will that look OK when rendered out at 50p and/or 50i? Or should I film in 25p so he can deinterlace his 50i down to 25p?

My last question is, why does anyone shoot in interlaced anymore with the internet (YouTube, Vimeo) and HD TV’s all using progressive now? I don’t have much understanding of this as I’m sure you can tell. I’m sure there’s a reason most of the professional SLR’s and video cameras record interlaced over progressive, I’m just curious what that reason is.

Thanks so much!
Jamie

[manono]

What he calls 50i is in reality 25 interlaced frames per second (or 50 fields per second). As long as you shoot at 25 progressive frames per second you should be okay.

My first question then is, can you successfully merge interlaced and progressive footage?]

Yes, although it might depend on the intended final output format (you didn't say). For DVD, for example, there's no problem at all. For YouTube his will have to be deinterlaced to 25p.

Should I just match his frame rate, i.e. 50p to match his 50i?

As I implied, 50p doesn't match 50i, not unless he bobs his to match yours.

I’m sure there’s a reason most of the professional SLR’s and video cameras record interlaced over progressive, I’m just curious what that reason is.

Not sure I can tell you, either, although there are some around here with strong opinions on the subject.

[Cornucopia]

If you give him 50p, and he knows how to properly deal with it (hopefully, since he is a "semi-pro"), he should be able to either get a 50i or 25p stream derived from the 50p (or use as-is if that's his goal). 50p would be the most manipulate-able while retaining the most quality. Remember, always start from the highest point possible, since "quality flows downhill".

Though the trend is clearly towards Progressive (and for future-proofing, it usually makes much more sense to shoot progressive), there are plenty of reasons still existing to use BOTH Progressive and Interlaced in current videography. It all depends on the desired outcome (target display/device/format/audience). Don't let anyone tell you otherwise - they are either shortsighted or have an agenda.

Scott

[smrpix]

Give him exact copies of your original files. That way he is starting from the best possible quality. Compatibility/degradation issues become matters of his choice.

(Frequently being on the receiving end of this scenario, I hate it when someone "helps me out" by pre-converting.)

[newpball]

My last question is, why does anyone shoot in interlaced anymore with the internet (YouTube, Vimeo) and HD TV’s all using progressive now?

Couple of reasons:

Old habits die hard
Job security
Sheer obstinance
Arrogance

You are right currently there are no good reasons to record interlaced. We now have the ability to run SD and HD at 50/60p or higher that is more than enough speed to produce a smooth video including fast sports events.

Interlaced video is from the old days and basically a hack that was necessary but nowadays it is no longer necessary. The thing is some people have a hard time dealing with progress and change.

[_Al_]

My last question is, why does anyone shoot in interlaced anymore with the internet (YouTube, Vimeo) and HD TV’s all using progressive now?

Couple of reasons:

-equipment does not grow on trees and cost money, so he sticks to his equipment which was not cheap
-delivery format is still Blu-Ray, there is no 50 frames per second specs for BD authoring
-viewers would hardly notice that he was using 50i instead of 50p

[jcarst85]

Thanks a lot for the answers guys. Totally solved my problem!

[hello_hello]

My last question is, why does anyone shoot in interlaced anymore with the internet (YouTube, Vimeo) and HD TV’s all using progressive now?

Couple of reasons:

Old habits die hard
Job security
Sheer obstinance
Arrogance

You are right currently there are no good reasons to record interlaced. We now have the ability to run SD and HD at 50/60p or higher that is more than enough speed to produce a smooth video including fast sports events.

Interlaced video is from the old days and basically a hack that was necessary but nowadays it is no longer necessary. The thing is some people have a hard time dealing with progress and change.

Any examples? Just one example of someone shooting interlaced for no other reason than obstinance and an inability to deal with progress or change?
Which jobs offer more security if you shoot interlaced?

[jman98]

-delivery format is still Blu-Ray, there is no 50 frames per second specs for BD authoring

50 fps is valid for 1280x720 video, as is 59.94 fps and even 24 fps in BD authoring. You are thinking of 1920x1080 video in BD where no frame rate above 29.97i is allowed.

[pandy]

Go for 50p as any lower format can be created from 50p (i.e. "50i", 25p), interlace is not supported by YT (it is coded as progressive and frequently this is visible as "interlace tooth" artifact when video is resized. Nowadays YT support 50p then it is not a problem to feed YT with 50p version.

[budwzr]

Maybe the guy didn't want anyone else involved in the project and is trying to find an excuse to dump you overboard so he can get all the credits.