Blu Ray output - can I mix frame rates?

G

glv

Member
i am anticipating a mix of 24p and 30p footage that i will need to mix into one blu ray. from what i understand 30p can be turned into 60i without much loss in quality. i have never authored blu ray discs before, so the question is: is it possible to have different scenes with different frame rates on one disc? one scene at 24p the next at 60i for example?
 
Yes and no.

People edit this way all the time - the 24fps footage is telecined to 30fps (interlaced, but do not confuse this with pure 60i video), which as far as NLEs are concerned, is regular 60i video, thus the framerates "match". Because of this, you could encode the resulting file in 60i, to maintain the differing framerates, but that still leaves you with your 30p issue.

Do not worry about it

BD spec technically does not cover 1080p/30 (huge oversight in my opinion), but that doesn't stop players/TVs from handling the content, so just as many companies did with DVDs, it is possible to flag a BD as interlaced, even if it's progressive. Encode your video with x264, and you can set the fake interlaced flag for this very purpose. (See: http://mewiki.project357.com/wiki/X264_Settings#fake-interlaced) The resulting encode can be dumped into whatever authoring program you choose.
 
glv said:
do you mean to 60fps? thanks for clearing this up. i will sleep better now knowing it can be done :)
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No, 30fps. As far as broadcast standards are concerned, pretend for a minute that 60fps doesn't exist (except in the form of 720p).

All video is either:

30fps progressive (30p, uncommon)
30fps interlaced (30i or commonly called 60i, which is understandably confusing, very common)
24fps telecined (as far as hardware is concerned, it's 30i, but it can be inverse telecined back to 24p, which most TVs do)
 
RX782 said:
No, 30fps. As far as broadcast standards are concerned, pretend for a minute that 60fps doesn't exist (except in the form of 720p).

All video is either:

30fps progressive (30p, uncommon)
30fps interlaced (30i or commonly called 60i, which is understandably confusing, very common)
24fps telecined (as far as hardware is concerned, it's 30i, but it can be inverse telecined back to 24p, which most TVs do)
Click to expand...

so i'm going from 24p to 30i (aka 60i), while 30p goes to 60i (aka 30i)? and they end up the same in the editor. i edit on a 60i timeline, then i output at 30p flagged as 60i?

i'm assuming the TV would read the 60i and play either 24p or 30p as required. are there quality sacrifices involved in this process?

lastly, can the telecine process be done within premiere, or do i need something else? thanks for all of your help!
 
glv said:
so i'm going from 24p to 30i (aka 60i), while 30p goes to 60i (aka 30i)? and they end up the same in the editor. i edit on a 60i timeline, then i output at 30p flagged as 60i?

i'm assuming the TV would read the 60i and play either 24p or 30p as required. are there quality sacrifices involved in this process?

lastly, can the telecine process be done within premiere, or do i need something else? thanks for all of your help!
Click to expand...

I haven't actually tried this in Premiere, since I strictly avoid mixing framerates (other than for slowmo), but in Final Cut, I've run into the situation, and it seemed to convert the framerates on-the-fly to proper interlaced formats when necessary. In FCP for example, the default timeline is interlaced for DV footage, but if you drop in progressive footage, it still looks progressive. It's just a matter of flagging vs. actual video type (though if you want to be technical, interlaced color is handled differently than progressive). I've placed 30p footage, 24fps footage, and 60i transitions (Created by FCP) in one timeline before, and it basically telecines the 24fps footage, while leaving the the other footage alone.

Basically, there's a lot less thinking involved in this process as most editors handle the conversions for you.
 
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