PAL GH1 i need an answer to this once and for all :)

terra1

terra1

Well-known member
ive got a PAL GH1 running the hack on the "c" settings, ive read alot of confusing things about the pulldown/deinterlacing stuff....

the PAL GH1 is 25p (1080p) in a 50i wrapper i hear.... can someone please without making me feel 1 inch tall tell me whats a wrapper? i understand pull down isnt needed with PAL as 25s fit neatly into 50i, or 2 25's from the 50i fit neatly together as 25p.

also when i import my FHD and SHD footage into my adobe prem CS5 AVCHD 25p timeline what do i have to do to it before i start editing?

until now ive been dropping it into the 25p timeline and its been looking great and exporting fine, yet i feel i should really know this question by now.

alot of diff people using diff terminology has got me in a blooming wrapper! and iam sure a few other people.

thanks if anyone reads this and posts a reply. :smile:
 
terra1 said:
the PAL GH1 is 25p (1080p) in a 50i wrapper i hear.... can someone please without making me feel 1 inch tall tell me whats a wrapper? i understand pull down isnt needed with PAL as 25s fit neatly into 50i, or 2 25's from the 50i fit neatly together as 25p.
Click to expand...

That the footage is in a 'wrapper' means that the 25p footage is saved in what, to the computer, looks exactly the same as a 50i video file. So, the information about the file tells the computer that the footage is interlaced. You have to be a bit careful that the computer tries to deinterlace the footage needlessly. This would just throw away resolution. Luckily, most NLEs won't deinterlace unless you explicitly tell them to.


terra1 said:
also when i import my FHD and SHD footage into my adobe prem CS5 AVCHD 25p timeline what do i have to do to it before i start editing?
Click to expand...

I'm not sure about this one, I don't have a GH1. What I do find with my HDV camera is that when I shoot 25p, it is better for me to put the footage in a 50i project because, like on the GH1, progressive video at 1080p on HDV is also in a 50i wrapper. Because the wrapper and the format of the project agree, Premiere CS3 will play it back without having to render. If I put the same footage in a 25p timeline, it will want to render even though the footage is already 25p, purely because the computer thinks it's actually 50i.

Does that help at all?
 
yeah thanks for the reply andrew, its always hard to understand fully but thanks for the info, iam gonna have a good search of the forums and read up on it all again :) i always find i need to be able to visualise something before i can understand its workings but this is a tuffy as its not a physical thing its all in word land if u know what i mean.

il get it soon and when i do i bet i say..... ffs why do people over complicate things hahaa, i was lost on the hack until i watched a users video and it answered alot of over looked questions.

sorry for the yap :o)

cheers again
 
Andrew,

I havent really understood the way the GH1 delivers its full high definition video. I understand that the sensor output is 25p. When the manual says that it creates a 50i wrapper, does this mean that it takes a whole frame and creates two fields, the first with odd lines and the second with even lines, or does it create two duplicate fields, each of which contains the whole frame?


I'm trying to work out how to get the most cinematic look to my video footage, and it seems to me that understanding about interlacing/deinterlacing might be key to getting the right cadence.
 
It does the full odd/even wrapper. Each interlaced frame is actually 1/2 frame so when they are re-combined they produce a full non-interlaced frame.

Chris
 
amathie said:
Andrew,

I havent really understood the way the GH1 delivers its full high definition video. I understand that the sensor output is 25p. When the manual says that it creates a 50i wrapper, does this mean that it takes a whole frame and creates two fields, the first with odd lines and the second with even lines, or does it create two duplicate fields, each of which contains the whole frame?
Click to expand...

Yep, the first one. Usually, the contents of each field of an interlaced frame are taken from two different points in time. Your camera changes this by populating the contents of both fields with information taken at the same time.

-Andrew
 
cbrandin said:
It does the full odd/even wrapper. Each interlaced frame is actually 1/2 frame so when they are re-combined they produce a full non-interlaced frame.

Chris
Click to expand...


So can I ask how does one convert 50i to 25p ? I use cs4 after effects and premiere pro but don't know how to deinterlace in either. There also seems to be many different types of deinterlace methods which I'm clueless about.

If I drop my 50i footage into a 25p timeline, will that automatically deinterlace ?
 
So does that mean when shooting Full HD it is not shooting true 50i, but shooting 25p?
Cheers, Rob
 
Roderz said:
So can I ask how does one convert 50i to 25p ? I use cs4 after effects and premiere pro but don't know how to deinterlace in either. There also seems to be many different types of deinterlace methods which I'm clueless about.

If I drop my 50i footage into a 25p timeline, will that automatically deinterlace ?
Click to expand...

No, it probably won't deinterlace. In Premiere you right click on the clip, select Field Options, I think it is, and check 'Always deinterlace'. It's not the best way of doing it but it's easy. There is also an option on the top left of the Output tab of Adobe Media Encoder to apply the setting to the whole project when you render it out.

In After Effects, by default it throws one of the fields away when you import interlaced footage. Andrew Kramer has a good tutorial about manually deinterlacing in AE.
 
Andrew,
See Chris's answer to my earlier question.
If the GH1 is not shooting true interlaced footage then why all this talk of de-interlacing?
I've just got myself a GH1 and assumed that it was 50i in full HD, but it seems that it is 25p in a 50i wrapper. So surely it is just 1 full frame field duplicated?
Also, AE doesn't throw away 1 field!

Cheers, Rob
 
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