24p vs. 30p Blu-ray

[Craig Kovatch]

I did some looking on the forum but coudln't find a definitive answer. Is there a difference in picture quality between burning 30p material to Blu-ray vs. 24p material to Blu-ray? I'm wondering because 30p is not supported.

[Jeff Harper]

It's not about picture quality so much but what available modes you have to shoot in with your camera and then considering where it's ending up. 30p is perfect for the web for example, and 60i and 24p and 720 60p are all compatible with Bluray. (and anything else I'm missing.)

If your video is for playing on DVD or bluray, like a wedding video or whatever, and it needs to look it's best, then you want to shoot in a mode that is supported on Bluray (and DVD if you're also going to make DVD copies for your customer).

It can get complicated, the main thing, IMO, is too shoot closest to match where you're going to end up.

[Jeff Harper]

Should add Jeff, that if 30p is not compatible with Bluray, then you can't use it anyway, so the question of which is better is kind of, well, I don't know. There is no picture quality for you with 30p for Bluray, because you can't do it. So if you have 30p footage, you would have to convert it to 60i or to whatever you choose because the original file won't work for Bluray anyway.

[David Jimerson]

Originally Posted by Jeff Harper

It can get complicated, the main thing, IMO, is too shoot closest to match where you're going to end up.

I disagree; shoot for what you want your project to look like. The difference between 24p and 30p and 60p isn't image quality, but motion characteristics. That affects the entire feel of your project and you should make it what you think best serves the project.

[Jeff Harper]

You're right David, to a degree, but if 30p is the look he wants and can't use it on Bluray, it's pointless to shoot in 30p, that's what I'm saying, and he needs to shoot in a mode that will be compatible with Bluray, if possible, so he can render without conversion.

If he's going to Bluray, then he should shoot in 720 60p, 60i, or 24p, none of which need converted. From those choices he can choose his look. I was trying to start him out with the basics of planning the workflow simply, which did ignore his original question.

Jeff, as David alluded, none of the modes is better in every shooting situation. 24p can look good depending on what you're shooting, but for general purposes 720p, and 60i are the safe bets. If you're not sure, read up on 24p by googling it to see the disadvantages and the advantages. And there are plenty of disadvantages.

[Phil Lee]

Hi

30p is fine on Blu-ray for the same reason 25p is. There is no official support for 30p (or 25p) because it is expected to be encoded as PsF, i.e. it's in a 60i wrapper, but will be 30p when played and de-interlaced on a progressive TV. This is how 30p and 25p has been handled in the broadcast world for decades.

Regards

Phil

[Jeff Harper]

So Phil, clarify for me, can 30p be used as-is on bluray without conversion to, or must it be wrapped in 60i?

[Phil Lee]

Hi

It must be wrapped in 60i, although I suspect most Blu-ray players would cope fine with 30p, you just might get problems authoring it if the authoring software is being strict. For anything commercial you would want a proper 60i wrapper.

The x264 encoder has a setting for fake interlaced, I think this encodes it as 30p for better compression but identifies the stream as 60i. This has worked fine for me with 25p to 50i. See 1080p - Authoring a professional Blu-ray Disc with x264

Regards

Phil

[Jeff Harper]

Thanks Phil for that info. That speaks to my point about keeping it simple. I'm assuming, perhaps wrongly the OP is not familiar with these concepts. If he can shoot in a mode that can export to Bluray with no fiddling needed to ensure compatibility, I would think it would be a no-brainer to go that route, but I'm not so big on achieving a certain look as some people are. I think camera and lens choice go a lot farther in creating a look than what can be done in post.

We don't know what he shoots, as he didn't tell us, but I personally choose my cameras as well as my frame rate, etc all with the end result in mind, but that is just me. For example, 1080i is perfectly fine for wedding video DVDs and Bluray, looks great. But since I also upload samples to the web, I don't want to have to deinterlace if I can avoid it, so I shoot in a mode that is ready to go for DVD, Bluray, and the web.

I shot a high volume of weddings this year and it's important to me to streamline where I can, so my point of view is based on that perspective. Meddling with four camera's worth of footage is just so time consuming.

[David Jimerson]

The look of 30p won't change when it's wrapped in 60i. In fact, most TV deinterlacers these days will make it pretty much straight-up 30p again.

[Tom Roper]

Originally Posted by Phil Lee

Hi

It must be wrapped in 60i, although I suspect most Blu-ray players would cope fine with 30p, you just might get problems authoring it if the authoring software is being strict. For anything commercial you would want a proper 60i wrapper.

The x264 encoder has a setting for fake interlaced, I think this encodes it as 30p for better compression but identifies the stream as 60i. This has worked fine for me with 25p to 50i. See 1080p - Authoring a professional Blu-ray Disc with x264

Regards

Phil

Phil, that's a great link, thanks! I've had the command line x.264 encoder but the getting started link from your post worked great to get me going again. Finally!

[Jeff Green]

I'll just add my recent experience. I shot a wedding in 30p on my DSLR. Edited and rendered it to Blu-Ray and then used my kids PS3 to play it back on our 1080p TV. Looked good!

I have to admit, I did not realize there was an issue with 30p and Blu-Ray but thought I would add my experience to your conversation. For what it's worth ;)

[Craig Kovatch]

Thanks for all the replys guys.

I'm more a hobbyist than anything, but I do some event videography. Nothing I shoot will end up on the web. It's either DVD or BD. I was just really curious if there was any picture degradation in having to convert 30p footage to 60i before burning to Blu-ray. I love the look of 24p, but man does it have it's limitations. I want to shoot in 1080 as much as possible, which means 30p for most situations.

Jeff, do you do a lot of shooting in 720p? Do you find clients notice the difference between 720 and 1080?

[Taky Cheung]

It's the encoder convert 30p material splitting the full frame into PsF as in 60i. 30p is preserved completed in 60i stream. It's not a wrapper, nor the BluRay player has to deinterlace it.