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Official Low GOP topic
  • 1003 Replies sorted by
  • @proaudio4

    Just change 1080i50 and 1080p24 GOP Size=3 to 1080i50 and 1080p24 GOP Size=6 and it should work fine. Sage's video looks great. I was using 6 GOP for my initial tests but like the 3 GOP better. But it's a very subtle difference. I did notice that autofocus on the 14-140 was a little snappier with the 6 GOP. And remember, it's hard to get a feel for this unless you watch it raw, so shoot your own tests with 3 and 6 and see what you like.
  • @randolfo

    "You say that we can begin to make final setting at least 24p on? With either 12 or 3 GOP is subjective, I'm still evaluating. But what about bit rates and other things. What do you say?"

    I haven't tried raising the bitrate on my settings higher yet, but I think someone (you?) set it to 60 and it worked. I haven't messed with 720p or 1080i modes at all yet as I am waiting for others for input. 1080P 24 was the only thing important to me. Today I am going to try and find the upper possible limit for GOP 3. The higher the data rate the better, the cost of SD cards is not a worry for me.
  • I use this setting - no problems

    P1000417_kl.jpg
    800 x 450 - 313K
    setb.zip
    482B
  • @kae
    Thanks Kae!

    I should mention I have not had a chance to sit down and absorb all the great info regarding the "testers" section.
    Since I'm in NTSC 60i land, If I change the 1080i50 and 1080p24 GOP Size=6, what do I need to change to have 1080i60 and 720P use the 3 or 6 GOP settings?
    I realize this may be obvious, but since I have not had a chance to look over this in detail, I don't want to accidently miss a setting.
  • @kae
    "Since I'm in NTSC 60i land, If I change the 1080i50 and 1080p24 GOP Size=6, what do I need to change to have 1080i60 and 720P use the 3 or 6 GOP settings?"

    I hesitate to guide you here since I have not done it successfully on the other settings. Mine only deals with 1080p leaving the other NTSC settings untouched. It does change 1080i/50 to a GOP of 3 but does alter the default bitrate for that.
  • @Butt
    "I use this setting - no problems"

    Awesome. I will test these today, especially the 720P. Thanks!
  • No problem Kae. I may just try the 24H setting.
    I take if I go into ptool and change the following parameters for 24H, this is all I need to do?:

    Video Bitrate 24H=50000000
    Video Bitrate 24L=32000000
    1080p24 GOP Size=3
    Video Bitrate 24H ADD=50000000
    Overall Bitrate=50000000
    Overall Bitrate 2=50000000
    Video buffer 24p=0x3600000
    1080p24 High Top Setting=42418
    1080p24 High Bottom Setting=29692
    1080p24 Low Top Setting=31178
    1080p24 Low Bottom Setting=21824

    Sorry if I seem like I don't know what the fuck I'm doing. LOL!
  • For someone who hasn't been following very carefully this whole low-GOP stuff, if we use GOP 3 for instance, does that mean we lose the ability to take advantage of higher bitrates 32-42 etc or can we still use 42Mb/s in conjuction with low GOP ?
  • @kae

    I am glad to hear their opinions on the 720p
  • @stefanos
    see you here: is Vitaliys setting mit GOP3 - and the MBit then go even higher

    P1000417_kl.jpg
    800 x 450 - 313K
    setb.zip
    482B
  • @stefanos
    "does that mean we lose the ability to take advantage of higher bitrates 32-42 etc or can we still use 42Mb/s in conjuction with low GOP "

    If you're referring to 1080 24p you can go much higher than 42mbit. I've seen 54mbit so far but that's in 24p. If you're referring to the ability to do 42mbit in 720p I haven't tested it yet, but @butt posted some settings above to try.

    @proaudio4
    Yes. The settings in your reply will give you 46-53mbit 1080 24p 3 GOP footage.

  • Very interested in stable settings people have had at 1080i 50. Kae it seems like you've had some success with this. EDIT just read the bit right at the start that VK said about testers knowing what they're doing. So that's me out! But following this with interest.
  • Mark_the_Harp :

    I´m looking forward for stable 1080i 50/60 settings, too. In my case, every bitrate above 30 mbit/s is too much.
  • Hey, just finished shooting a little short last night with the 3GOP setting... footage look amazing! Even the stuff at ISO 1250 and 1600 is very clean! I should have it up in the next few days. The story (for lack of a better word) is nothing special, but I just wanted to a do a test involving actors since I think the shorter GOP motion is more noticeable with people that with stationary objects and such.

    On another note, I did get a lock-up and had to remove my battery when I tried to shoot some 720p 60fps stuff. Is this a know problem, or just a fluke I came across?
  • @Kae

    I Kae, discard the 12 GOP for cinema, 6 or 3 ok. As far as I tried bitrates up to 800000 and no problems, but do not see big differences, so we placed with regard to bitrate. I think that we can determine the order of the settings for 24p ... unless it comes out of something striking. If I can give you some advice post production, instead of importing the files directly into Avid, Cineform trial, see really change the range of cromatic dinamic.I am very satisfied with these settings. I just finished a short film with these settings, they were all stunned. You currently are using that setting of bitrate settings?
    do you think we can do something about it?

    1080p24 High Top Setting=42418
    1080p24 High Bottom Setting=29692
    1080p24 Low Top Setting=31178
    1080p24 Low Bottom Setting=21824
  • I'm still doubtful about 1-GOP, but I liked LPowell's 3-GOP 720p30 AVCHD setting. 1080p24 3-GOP sounds enticing.
  • Hang out a little guys, just had a little breakthrough in 24p. Will post in a minute.
  • KAE 1080P 24 3 GOP Extreme - Please testers only for this:

    Managed to get almost 60MBIT on these modified 1080 24P 3 GOP settings. The footage is stunning and I think about as good as it's going to get (but let's try and make it better!). To test I used the Pappas codec crash chart (not the star chart). When I tested it in the GH1 the camera would just blow up and run away. But with these settings I did two minutes on it and the GH2 wasn't even breathing hard but WARNING: When trying to play back the files of the TEST CHART in camera, the camera froze. BUT the footage played back perfect on the computer and ingested perfectly into the AVID. This is why I think we've reached the upper limit as for me, I want to be able to play back footage in camera. For EVERDAY NORMAL HIGH DETAIL footage, you're not going to have a problem with these settings as the codec crash chart stresses the cam like nothing else in the world. (I would attach the chart but it's copyrighted by Michael - if he's lurking and gives permission I will post it, try an internet search for "Pappas Codec Crash chart").

    Screenshots of the codec crash chart and the settings file are attached. I've included some of randolfo's and butts settings for 1080i and 720p just to make sure those modes don't crash with my settings. I'm sure you can get a lot more out of those modes, I just don't use those modes so I don't focus on them.

    What I basically did is multiply the default 1080 high low top bottom defaults by 2.2X and raised the bitrate to 70mill. Please test and see what you think. I think we've reached the ceiling for 1080 24p.

    If 60mbit at 1080 24p 3GOP is as high as this cam ever shoots I'm fine with it. And thanks again to Vitaliy, you are a god among men.

    FWIW: I think if you are a filmmaker and your goal is to shoot 24 1080P with a GH2 for eventual film-out to 35mm you are shooting yourself in the foot by not using 3GOP. The frame to frame motion transfer will look even better than 6 GOP.

    Edit: Per tests below, the following can be unchecked in your settings file as they are redundant - you will still get up to 60mbit data rate without them:

    Video Bitrate 24H ADD=70000000
    Overall Bitrate=70000000
    Overall Bitrate 2=54000000
    KAEEXTREME60MBIT108024P3GOP.JPG
    1267 x 671 - 165K
    KAEEXTREME60MBIT108024P3GOPA.JPG
    1269 x 661 - 161K
    setd.zip
    577B
  • @kae

    Can you repeat this testng, but this time remove patches below one by one (removed one, tested, etc), not change values, just uncheck:

    Video Bitrate 24H ADD=70000000
    Overall Bitrate=70000000
    Overall Bitrate 2=54000000
  • Running out to dinner but will do it quick.
  • Waiting for my battery to charge. Meanwhile, here's the codec crash chart - Vitaliy please take this down if it is inappropriate.

    Edit: Careful using this chart with these settings. The clip will lay down and playback on computer but if you try and play it back in camera it corrupts the card and you will have to copy your footage off it before reformatting. It does not do this with normal footage so far.
    new codec tests chart PAPPASARTS.jpg
    1920 x 1224 - 2M
  • @kae

    Can you tell me how testing chart can be inappropriate?
    May be if you look at this in exactly 24 degrees with one eye closed you'll see huge prick?
  • Below are screenshots of my settings with just 'Video Bitrate 24H ADD=70000000' unchecked.
    It seems a slightly lower data rate, right?
    Moving on to the next one.
    KAEEXTREME60MBIT108024P3GOP24HADDUnchecked.JPG
    1268 x 671 - 172K
    KAEEXTREME60MBIT108024P3GOP24HADDUncheckedA.JPG
    1266 x 675 - 171K
  • @Vitaliy
    "May be if you look at this in exactly 24 degrees with one eye closed you'll see huge prick?"

    I've read a few of those on this board but never seen one ;-)
    I think Pappas designed this himself, so without his permission....
  • Below are screenshots of my settings with 'Video Bitrate 24H ADD=70000000' and Overall Bitrate=70000000 unchecked.
    KAEEXTREME60MBIT108024P3GOP24HADD_OverallBitUncheckeda.JPG
    1267 x 670 - 166K
    KAEEXTREME60MBIT108024P3GOP24HADD_OverallBitUnchecked.JPG
    1274 x 674 - 171K
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