Confused over 24psf mode

A

AdamLPhotography

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I've been shooting footage using 24psf mode from the SDI out to a BM Hyperdeck Shuttle 2 using DNxHD. When I view the .mov files using Quicktime examining the properties the footage is reported as 59.94, which I guess according to standards in a 60Hz environment is actually 29.97 - it's just bundled into an interlaced 59.94 stream.

The question I have is - what's the proper way to import this footage into an NLE so the project plays back and renders 29.97 without having to resample? I'm using Sony Vegas 10e as my editor if it matters (and I suppose it does.) I've tried setting the project's properties to 29.97, but it still looks like the footage isn't smooth, so I'm guessing Vegas isn't reading the stream correctly.

Anybody have experience with this that could give me some pointers? Do I need to transcode it first? If so, what's a good utility to do this with?

Looking at the footage playing back in Quicktime it looks fantastic. There's no ghosting, etc. Quicktime is also reporting the footage is being played back at ~60fps. If the SDI out was set to 24psf shouldn't playing it back at this speed cause the footage to be ghosted and look ugly? I'm confused here. I can always just go with setting the project at 59.94 and be done with it instead of getting it to 29.97, but I'd like to understand what happened here.

Thanks!
 
Well, the issue is -- why is the footage being recorded as 59.94i in the first place? If you've set the AF100 to 24PsF and you're recording in 1080/24p, then the file that gets recorded should be a 24p file. And you should edit it in Vegas on a 24p timeline.

Is the BMD not capable of recording a native 1080/24p file?
 
I guess the confusion stems over what happened when I set the AF-100 to record 1080/24p in 24PsF mode. It wound up recording everything interlaced. When I set it to record 720/24p in 24PsF mode, that's when I wound up with files that were recorded 59.94. I'm sure the BM is fully capable of recording whatever is being output from SDI. I'll go fire it up and double-check what I'm seeing. I'm still learning a ton about recording, so it's entirely possible that I messed something up. Luckily I had the AVCHD footage to work with though. The AVCHD footage confuses me too, though. I had it set to record in 1080/24p and the AVCHD file is reported by VLC player as Resolution: 1920x1080/Frame rate: 47.952047.

Anyway, I'm going to go set up a test here and see what I come up with. Thank you for the quick reply Barry. Maybe I need to go watch your AF-100 DVD again about... a hundred times or so and this might eventually sink in. ;)
 
Just completed the test. Recorded to the internal SD as well as Hyperdeck Shuttle 2 simultaneously. I used VLC Player to get the media info for all the clips.

1080/24p in 24PsF mode
AVCHD:
Codec: H264 - MPEG-4 AVC (part 10) (h264)
Resolution: 1920x1080
Frame rate: 47.952047

DNxHD:
Codec: DNxHD (AVdn)
Resolution: 1920x1080
Frame rate: 23.976023

720/24p 24PsF
AVCHD:
Codec: H264 - MPEG-4 AVC (part 10) (h264)
Resolution: 1280x720
Frame rate: 47.952047

DNxHD:
Codec: DNxHD (AVdn)
Resolution: 1280x720
Frame rate: 59.940059

Is 24PsF supposed to output interlaced at 720/24p?
 
24PsF isn't used when you're in 720p mode. It's only valid for 1080. So when in 720p, the output is always 720/59.94p, and if you're shooting a slower frame rate (like 30p or 24p) then it uses frame duplication to fill out the sequence to a full 60fps.

The DNxND 1080 file is reporting just what it should.

I don't know why VLC is saying that it's 47.952047, that seems silly, the file should be 23.976fps...
 
So in an NLE if I set the project to 23.97 will it work magic to drop the extra frames from the 720p footage, or would I have to do something else to get a 720/24p clip?

Also that's a hell of a gotchya for 24PsF mode. I wish the guys who wrote the firmware would grey it out if anything other than 1080 was selected. I suppose it's normally not a big deal until someone wants to use an external recorder. This project has been a whole series of learning experiences, and not the pleasant kind. :(
 
24PsF only exists for 1080, always has and always will. It's only ever valid when you're shooting 1080/24p mode. Won't work in 720, won't work in variable frame rates, it's only for shooting and outputting 1080/24. It was made for monitors, but recorders use it too.

In every NLE that I use, you just drop the original 1080/24p recording right on the 24p (well, 23.976) timeline and it just works properly...
 
Whatever VLC player is telling you, what do those files (the AVCHD files) read as in Vegas?

The timeline doesn't matter to reading this; what do the clip properties tell you?
 
I realize that now, Barry, but I think Panasonic could have easily disabled 24PsF just to avoid confusion if anything other than 1080/24p is selected, especially if 24PsF is only ever meant to be used when the AF-100 is set to 1080/24p.

David it lVegas says it's 23.97. Apparently VLC is just being goofy and reading the stream's properties incorrectly, although it plays it back just fine.
 
That's the point -- 24PsF *is* disabled when using any other mode. It's inherent in the system. 24PsF can only ever be used with a 1080i output when the system is set to record 24p. In any other scenario, it's disabled.
 
Barry_Green said:
That's the point -- 24PsF *is* disabled when using any other mode. It's inherent in the system. 24PsF can only ever be used with a 1080i output when the system is set to record 24p. In any other scenario, it's disabled.
Click to expand...

Perhaps, but the ability to turn it on and off is still there, regardless if it affects the output. I'd think that it would be more intuitive to just disable the ability to toggle it on/off and display it as "off" if anything other than 1080 was selected.

So the bottom line is the output via SDI is always either interlaced or 24p when recording 1080. Recording 1080/30p via SDI isn't possible as it can only output interlaced at 1080 unless 24PsF is on, correct? Or will the AF-100 shove a 30p stream into 1080/60i?
 
The SDI output is always interlaced. 24PsF is a way to embed 24p within an interlaced 48i stream.

30p and 24p are "known" by intelligent recorders or monitors by the flags that are embedded in the data stream. If you set the camera in 30p, it outputs a 60i data stream, with 30p "flags". If your monitor or recorder is aware of the flags, it will put the fields back together to be a proper progressive frame and display/record that. If your monitor or recorder is unaware of progressive flags, it'll display it as 60i.

24PsF is a thing Sony came up with years ago to allow direct progressive over an interlaced 1080i infrastructure; it changes the frame rate to 48i and otherwise works the same way as 30p does within a 60i stream.
 
Ahh I see. That makes a lot more sense now. So it seems as long as the NLE and recorder understand the flags then I can still get 30p and 24p footage out of the 1080i stream. Thanks for the explanation, Berry! It's definitely not something that makes any sense to the average Joe. Would have been nice if they'd just let a stream be a stream, and not have to do all sortsa fancy tricks so the user can (eventually) get the res and rate they're attempting to target.
 
Yes, that certainly would have been nice... but if they did that, then there'd only ever be 1080i, no 1080p... so, yeah, the flags are the compromise that we have to live with to embed 24p within a 1080i stream.

Our only real hope is that 1080i will prove to be the last time we ever have to deal with interlace, and that all future 4k/UHDTV/etc standards will all be all-progressive...
 
Barry_Green said:
Yes, that certainly would have been nice... but if they did that, then there'd only ever be 1080i, no 1080p... so, yeah, the flags are the compromise that we have to live with to embed 24p within a 1080i stream.

Our only real hope is that 1080i will prove to be the last time we ever have to deal with interlace, and that all future 4k/UHDTV/etc standards will all be all-progressive...
Click to expand...

All-progressive at selectable refresh rates.
 
Perhaps 300Hz, so we can forever banish the 50Hz/60Hz divide... 300Hz lets you play all frame rates with no cadence complications. Well, 24p would have a padding frame here and there, but much smoother than at 60Hz I'm sure... :thumbsup:
 
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