GH2 GH2 shooting 30P in 1080?

S

Scott_Spears

Well-known member
Hi Folks,

Sorry for the dumb question, but I am considering getting a GH2 to complement my AF100. I have several clients who want to shoot 1080p at 30fps and I look at the specs on the GH2 and can't see that it will shoot 30p? Is this true? Is there a work around? Or a hack?

Thanks,

Scott
 
That's what HBR does in firmware v1.1 in an NTSC GH2 - gives you 24Mb/s 1920x1080/30P. I use it for all web-destined work and it's perfect.
 
HBR mode on the GH2 is a little confusing because it's a progressively-scanned video stream that's encoded within an interlaced AVCHD file. In NTSC mode, the sensor is scanned at 30p, divided into interlaced fields, and encoded in interlaced 60i format. In PAL mode, it's scanned at 25p and encoded in 50i format.

Unlike the AF100, however, the GH2 fails to tag its HBR files with the proper metadata to indicate that they contain a progressive video stream. The GH2's HBR files are formatted exactly the same as its fully interlaced FSH files and there is no explicit way for a video editor to distinguish between them. As a consequence, it's important to verify that HBR files are decoded as progressive streams after importing them into your video editor. For example, in Adobe After Effects, you'd use the Interpret Footage dialog to set Separate Fields OFF. Neglecting to do this will often produce noticeable interlace artifacts your edited footage.
 
There's also the VMM mode which shoots 30 FPS (without sound) then plays it back at 24 FPS. That gives higher quality than HBR and is very simple to work with - no flagging issues to deal with.

It's very popular for music video work but doesn't work at all for anything where you need dialog or other sync sound.
 
lpowell said:
HBR mode on the GH2 is a little confusing because it's a progressively-scanned video stream that's encoded within an interlaced AVCHD file. In NTSC mode, the sensor is scanned at 30p, divided into interlaced fields, and encoded in interlaced 60i format. In PAL mode, it's scanned at 25p and encoded in 50i format.

Unlike the AF100, however, the GH2 fails to tag its HBR files with the proper metadata to indicate that they contain a progressive video stream. The GH2's HBR files are formatted exactly the same as its fully interlaced FSH files and there is no explicit way for a video editor to distinguish between them. As a consequence, it's important to verify that HBR files are decoded as progressive streams after importing them into your video editor. For example, in Adobe After Effects, you'd use the Interpret Footage dialog to set Separate Fields OFF. Neglecting to do this will often produce noticeable interlace artifacts your edited footage.
Click to expand...

All the software i use edits and renders Pal 25P HBR fine and look Progressive after and it is BD compatable,the reason the GH3 is not worth it for me at present is because there are no BD compatable Progessive frame rates except 24P which i never use.So it would be back to 50i on BD a downward step for me.
 
Thanks everybody for the info. I'm downloading the firmware update as I type. I ordered the GH2 and it's on it way!!!

Scott
 
flinty said:
All the software i use edits and renders Pal 25P HBR fine and look Progressive after and it is BD compatable
Click to expand...

Blu-ray itself cannot handle 25p, from any camera. (Nor 30p in ATSC countries.) The authoring software will convert it to 25i before burning.
 
More dumb questions. Ok, I loaded up Firmware 1.1 and under REC MODE I have:
AVCHD (1080i)
AVCHD (720p)
MOTION JPEG

Then under REC QUALITY there is:
SH
H

Am I to assume that under 1080i is the 30p mode because the 'i" confuses me because I thought that meant interlace and not progressive.

Again, sorry for my ignorance, but you'd think they just have something read 30p or 24p and not H or SH or FSH.

Thanks,

Scott
 
No - the "i" stands for interlaced and is not what you want.

The mode could be labeled better but they become second nature after you get used to it.

You have to actually go into the "menu" not the "quick menu" in order to get to these. 30P (on NTSC cameras) is labeled HBR (that's the version with sound) or in the VMM mode you can select 80% (to shoot at 30P and have it playback at 24P without sound for music video style slow-motion).

In your case, I'm guessing HBR mode is what you are looking for. Just use menu, not the usual quick menu to get there - it should be right next to the Cinema 24P modes.
 
Cavemandude said:
Uh, that would be 50i not 25i.
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Uh, there's actually no such thing as 50i, which technically means 50 interlaced frames per second.

The convention is to list the vertical resolution, followed by an i or p as appropriate, followed by a slash, and then the FRAME rate. Like this:

1080i/25

The short form convention is to drop the resolution and slash, and move the i or p after the FRAME rate, like this:

25i

You do NOT list field rate. You always and only list FRAME rate. That so many camera makers get it wrong is no reason for us to do it wrong as well.
 
Not exactly true. Traditional 50i is actually 50 frames per second - that is each "half" is captured separately from the sensor at different times. HBR mode is not actually 50i; rather it is 25p in a 50i wrapper because both "halves" of each frame are captured in a single sensor operation. It's kind of a bastard format that doesn't precisely fit into either category. The same logic applies to 30p wrapped in a 60i wrapper. Although it is a single image capture that accounts for both interlaced halves of the frame (which makes it like 25p from an image capture standpoint), they are encoded as if they were different images (which makes it like 50i from an encoding standpoint).
 
Jim Simon said:
Uh, there's actually no such thing as 50i, which technically means 50 interlaced frames per second.

The convention is to list the vertical resolution, followed by an i or p as appropriate, followed by a slash, and then the FRAME rate. Like this:

1080i/25

The short form convention is to drop the resolution and slash, and move the i or p after the FRAME rate, like this:

25i

You do NOT list field rate. You always and only list FRAME rate. That so many camera makers get it wrong is no reason for us to do it wrong as well.
Click to expand...

"25i" and "30i" are archaic and confusing, IMO. They don't have "frames"; they have two mis-matched fields per "frame."

The problem with it is that when you're shooting "25i" or "30i," you're not shooting 25 or 30 pictures per second. You're shooting 50 or 60. They're different moments in time, not halves of the same picture.

The upshot is that objects move 50 or 60 times per second, not 25 or 30, and it's the number of motions per second which make a frame rate everything it is from a visual standpoint.

To wit, 50i moves exactly the same as 50p, and 60i moves exactly the same as 60p. And as it's the motion signature which is the reason for choosing a frame rate, that's more important, and it's more accurate to call them "50i" and "60i" than it is to call them "25i" or "30i."

I think the camera manufacturers are on the correct trend, and the archaic, inaccurate terms of "25i" and "30i" need to be retired.
 
Thanks everybody. I figured it out. Now it's time to test it with my AF100 to see what are the best settings for matching the two cameras up. If anybody knows any good recipes, I'm all ears.

Thanks again,

Scott
 
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