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25p official topic, aka Don't cry for me Argentina
  • 236 Replies sorted by
  • _gl_gl
    The problem flicker is caused by the shutter speed, so you have to use a multiple of the mains frequency - 1/50 or 1/100 works for me (faster doesn't).
  • stolpis100stolpis100
    @_gl thanks, and I assume as you can shoot at 50fps, there should no negative flicker issues when shooting under 50Hz lights?
  • alcomposeralcomposer
    Mostly everything on commercial TV (sitcoms) are shot on 24p...
    Lets all get behind the next hack and test it to the limits!
  • MimirsanMimirsan
    Looking at current batch of hacked 720p footage on GH2 it looks very very nice with lots of detail...way beyond GH1s...and way beyond 1080p on Canon dslrs. ;-)
    This is why I aint selling my GH2...just yet ;-)
  • _gl_gl
    @ stolpis100
    1. 720p on the GH2 is true progressive, not wrapped in anything.
    2. yes, except 1/25 isn't available as it would be slower than the frame rate (well, except in manual focus mode, but then it halves the framerate).
    3. I'm sure V. will be able to increase bitrate, but you can't make up for resolution loss. 720p has less than half the res of 1080p.
  • stolpis100stolpis100
    I am now considering the 'Emergency Back-Up Plan'. ie shooting 720p50 then interpret the footage as 25p in premiere pro, and speed it up 200% to get normal speed again. I did an entire shoot like this on the 7D about a month ago and it worked fine, plus I had the option of slowmo when desired. My questions about this plan are:

    1. I am still slightly unsure how the whole 720p in a 1080i wrapper thing works. Are we getting a true progressive 1280x720 image here?

    2. Can I still use the whole range of shutter speeds?

    3. Are we going to see a good enough increase in the available bitrate in this mode so that we can get anywhere near matching 1080p24?

    On a side note, if 1080 is urgent, upscaling 720p to 1080p is not too bad and especially so if you are using an a plugin such as InstantHD.

    This workflow is far more efficient than any speed changes and all the inherent irritants that come with it.
  • PhilMyselfPhilMyself
    Well if the AF-100 wasn't so expensive, i would buy one.
    For Pal users, this is really a bad news. I'm so disappointed...
    In fact I'm thinking of selling all my GH2 stuff and get a 7D !
  • MimirsanMimirsan
    "Maybe we all have to just get the AG-AF100 :-( "


    Thats exactly what Panny wants you to do...resist! lol

    I still have a lil red GH1 ;-)
  • pkramerpkramer
    So, who would like to swap for my gh1 hacked? :) it worked in 25p.
  • alcomposeralcomposer
    2 questions... is there any chance 25p can be output over HDMI?
    Is the sensing frequency 'hard wired' to the chip through modes?

    I am guessing that the 25p hack simply combines 50i? (which is not the worst thing is it?) One would have to question how the AG-AF100 does 25p?? Maybe thats just deinterlaced 50i??

    Maybe we all have to just get the AG-AF100 :-(
    Maybe we should all wait to see what VK has been able to put together in 61... If anything this project has shown : when there is a will- there is a way...

    Lets keep our spirits high!
  • MimirsanMimirsan
    Bloom was mistaken with 25p...he later realised.
    I think folks should for now just accept that full on native 25p wont happen anytime soon.
    VK's great but he aint a miracle worker.
    Im guessing some things can be hardware related or require extensive access to certain parts that he may not be able to.
    If anyone is to be asked about taking action with 25p... its Panasonic...and these are the fuckers who dont listen to customers or release new firmware with worthwhile updates.
  • fehafeha
    If I remember right, Philip Bloom had a pre-production GH2 and had 25p, later on was complaining about it's removal in production stage , so was it firmware or hardware change ?
  • Donnie88Donnie88
    @stip

    "I'm trying to understand but I don't.
    Is 25p for GH2 ruled out now or not?

    > In upcoming PTool you'll see quite stable 25p, but. It only has first field in top part, below is garbage.

    So despite the sensor not having 25fps setup there will be a 25p option - but it won't work. Will it never work or is there a chance that it can be fixed?

    I'm confused?!"


    That's exactly what I'm trying to figure out.

    So the 25p option will be there, but it won't look good?
  • _gl_gl
    > GH2 don't have 25p mode amongst sensor setup modes.

    @V., is it possible you can add new sensor modes, or modify the 50p/i ones for 25p? I assume these modes are just a collection of timing/windowing parameters?
  • Donnie88Donnie88
    Wow...so is that it? No 25p for the GH2 then?

    Is this confirmed?
  • mrbillmrbill
    @Ptchaw - I'll repeat what I said before - if you're originating footage for a programme for ANY terrestrial broadcaster in the UK, you CANNOT conform from 24p to 25p. Please do not assume I don't know what I'm talking about, because post-producing for broadcast has been my day job for over 20 years. Feature films are often sped back up, but you'll see all kinds of motion artifacts (24 to 25fps pulldown cadence, where a field is added every 12 frames to make up the numbers). Speeding up footage by 4% in a non linear editor often results in motion smearing and other artifacts.
    Every programme submitted to a UK broadcaster which has been edited by an independent post house is subjected to the most rigorous tech checks imaginable, and a 24-25fps conform would never survive this process. This is without starting to mention stuff like not shooting at native mains frequency to avoid light flicker and so on. So whilst the 24-25 conform workaround might work for you, it doesn't work for me, and I can't imagine why you're so negative towards a whole bunch of people who'd like to use the camera in this way. You don't need it? Fine - but don't deny us the opportunity to request 25p on these forums.
  • Mark_the_HarpMark_the_Harp
    @thecrane That might be the case although I actually like 24p for when I'm just hosing around doing home video of the children or whatever. But only because it has more detail and it's quite fun to take the odd still off it. Just wish I had that same quality at 25/50!
  • thecranethecrane
    Can the 24p mode be modified to 25p at all ? Or is that limited due to the way its hardcoded in the camera ?(probly because of no sensor setup for 25p as previously stated by V) It would be a fantasy if people could sacrifice 24p mode for 25p.
  • MimirsanMimirsan
    Best solution would be high bitrate 50i FSH and deinterlace...second best 720p 50p SH to 25p

    As long as mudbreakup issues are hopefully sorted via bitrate increase...all will be pretty good
    Prem pro does well with deinterlacing.
    Less of a headache than 24-25p conforming.

    50i high bitrate looks great on hacked GH1...25p native has a very slight improvement...but cant figure why.
    On the hacked GH1 50i was more stable at highest bitrates than using the 25p native patch.
  • Mark_the_HarpMark_the_Harp
    Can't argue with any of that! Just seeing what the best solution is for those of us using the GH2 who have to do 25p.
  • madactmadact
    @Mark_the_Harp It's a two edged sword... less flicker, better motion, in theory, but ugly jaggies on verticals when panning...

    Personally I hate it as it makes computer vision algorithms more complicated, and for watching video, most computer playback software seems to update both fields at the same time X-P . OTOH you tend not to notice it on TVs as they're designed with interlacing in mind and do it properly.

    I don't really have personal experience with modern TVs though, I stopped watching broadcast / cable years ago and these days all my media is viewed via projector on a 120" screen :o)
  • Mark_the_HarpMark_the_Harp
    @madact I was thinking more in terms of in-camera, ie higher bitrate for 1080 50i if we can't have 25p. Or is 1080 50i basically never going to look that good whatever you do with bitrate?
  • madactmadact
    Mmm, of course, rolling shutter, just another thing to worry about :oS well, we should get global shutter on the sensor by GH3 or GH4, right? ;o) Well, I suppose if you're pegging out for a GH2 and some nice shallow DOF glass a couple of cheap hardware store floods, PARs and a fresnel won't break the bank...

    Shame about the sensor modes - I take it 1080 at 50 & 60 is only "i" from the sensor, but any lower frame rate or res will get "p"?

    As for making 50i better, I'm sure it's possible - the techniques twixtor uses should be very applicable, I don't know if they do an i-to-p conversion (haven't played with their stuff), but if they don't, they should...
  • Mark_the_HarpMark_the_Harp
    Silly question but can 1080i 50 be made any better?
  • _gl_gl
    Oh : ).
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