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Official Low GOP topic
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  • @cbrandin

    FWIW, I always found a GOP of 6 was more stable on the GH1 and probably the GH2. When using GOP6 with the 1080p 24N hack on the GH1 I found the auto focus on the 14-140 was a helluva lot faster than a 3 GOP. It's true to a lesser extent on the GH2. Could never figure that out...
  • After all the shooting I did in Tokyo, Kae's settings (modified to a lower 50mbps) were very stable. I think I am going to be using 6 GOP for extra stability for the time being.
  • @cbrandin definitely to mess with buffers more. I was able to get stable GOP1 with adjusting buffers for over an hour but the bitrate ended up being sh*te... anyone got any solutions for keeping the bitrate up yet?
  • @telkitachki
    here a GOP1 Setting for testing - vegas pro 10: 47,952fps (!?) for 1080/24p
    seta.zip
    559B
    GOP1.jpg
    800 x 435 - 149K
  • @Butt
    >>here my GOP1 Setting for testing >>

    It seems that the mjpeg-patch of lpowell is included, also 720p60 with b-frames - is that right? Does the gop1 1080p24 and the 720p60 work without any crash - is it really stable? Is it necessary to shoot a 1080p first to get 720p60 working?
  • @nic2011
    >Is it necessary to shoot a 1080p first to get 720p60 working? yes!!!
    > Does the gop1 1080p24 . . . work without any crash - is it really stable? is not stable!!!
  • @producer

    Why did you convert your video sample above from 1080 to 720?
    It suffers badly from this
  • < Why did you convert your video sample above from 1080 to 720?
    It suffers badly from this >
    Yes, I perfectly know that, but the purpose is just for faster upload. Even after downconverting, the quality can be felt, right? If you reach even 200Mbps and you decide to make a short movie, for example 20-30min., do you really think to upload it real?
    That's why I shared my point about that matter not one time only - any extreme bitrate is not the key, but the idea to be filmed...
    So, any other notice about the picture?
  • GOP3 really is better???
    i found this:
    [Vimeo]
  • @butt little bit of an unfair comparison. look at 1 to 2 and 3 to 4 positions. not sure if different settings were used/lenses, etc... who knows?!
  • @driftwood
    no not unfair - see you vimeo are same: Lens 14-42mm, nostalgic -2 all
    where is the problem for you!?

    and i think, No. 2 is GOP3 "and a tad better" No. 3 and 4 is difficult
  • @kae After looking at detailed anaylsis of last weeks setD settings bringing into an FCP X environment and with its auto convert to prores the audio is exactly 12 frames out of sync from the pictures ( ie the images are 12 frames behind the 48k audio. ;-)) . But you probably already found that out. An easy resync issue in post but wondered if you'd looked at this further?
  • First post here. Count me in as a supporter! Thanks Vitaliy and everyone else that's helping out. This is seriously cool!

    I have several questions that I believe are pertinent to this thread having read all 11 pages:

    1.) I've read "24pN" a lot on this thread. What is this? I've heard of 24p, 30p, 60i, but never heard of 24pN before.

    2.) It's been mentioned that at GOP3 the cadence is IBB. Is it a setting that drops the P frames, or will this always happen at GOP3? In other words, will it be IPP if you don't change some other setting? If not, why does the camera choose to ditch P frames over B when the GOP is shrunk to 3?

    3.) I don't understand why ANY Class 10 card should have write speed issues even at 100Mbps. A SanDisk Extreme card is 30MBps. That's 240Mbps. TOTALLY enough overhead, it would seem. Even at 15MBps that's still 120Mbps, so plenty of overhead for any extreme setting listed in this thread. Am I missing something here?

    4.) As I'm understanding it, 65Mbps is the maximum rate for a GOP of 3. It's also mentioned that GOP 6 is almost indistinguishable and possibly more stable. With the encoder having to work harder, though, on more encoding one P frame instead of one I frame over six frames, does GOP6 require slightly lower bitrates to run stable relative to GOP3? In short, what's the max stable bitrate at GOP6?

    5.) So by running a high bitrate GOP3 in 24H, we're pretty much giving up 24L completely due to bugginess?

    6.) This is probably the most important question: This is my wife's primary photo camera as well. Does ANY of this have any effect on the photo side of the camera?

    Thanks in advance, and you guys are studs!
  • @driftwood

    "last weeks setD settings bringing into an FCP X environment and with its auto convert to prores the audio is exactly 12 frames out of sync'

    Are you talking about your settings or mine? I've been using C settings, but even my former settings were not out of sync. I've been on the dub stage for 30 years and can spot 1 frame out of sync in a heartbeat, 12 is huge, that's 1/2 a second. If this was true every single person using these settings would be posting this. You need to check your workflow. The extreme 65 mb/s settings import perfectly into avid and the sync is bang on. Perhaps settings got jumbled somewhere for you? All you need to make the 65MB/s 1080 24P 3 GOP work (with the 10 frame glitch of course) are these:

    Video Bitrate 24H=65000000
    Video Bitrate 24L=35000000
    1080i50 and 1080p24 GOP Size=3
    Video Bitrate 24H ADD=65000000
    Overall Bitrate=65000000
    Overall Bitrate 2=54000000
    Video buffer=0x3000000
    Video buffer 24p=0x3600000
    1080p24 High Top Setting=42418
    1080p24 High Bottom Setting=29692
    1080p24 Low Top Setting=31178
    1080p24 Low Bottom Setting=21824

    Perhaps you've changed those?

    Download my 65mbs motion test clip here where you can see sync visually. It's bang on:
    http://www.filesonic.com/file/1606622101
  • @Butt

    "GOP3 really is better???"

    Tests like these prove nothing for 3 GOP. The camera and subject have to MOVE and MOVE A LOT to see any difference with a shorter GOP. With a static camera and someone slowly turning their head and smoking, the stock GH2 at 24mbit with a 15 GOP will always look great. And there is no way to judge the motion effects of 3 GOP on a Vimeo encoded clip. Their encoder is pure crap when it comes to encoding motion, it stutters like crazy. The only way to judge is to download the original .mts file. If it's an edited transcoded file and you don't know someone's workflow, how do you know what you're looking at?
  • @Butt
    >>here my GOP1 Setting for testing >>

    These settings crash for me in 1 second shooting the pappas death chart on a class 10 card.
  • @geddyt
    "This is my wife's primary photo camera as well"

    I really think unless you're trying to shoot an indie movie or commercials for broadcast with this cam you don't need the 65Mb/s settings. Butt has some nice settings with lower bitrates that are probably more stable and if it's your wife's cam she doesn't need to put up with the 10 frame glitch that will always appear on the front of the extreme hack setting clips. 50Mb/s 6 GOP settings are great and they will more than suffice for 95% of the work people with do with these cams until Vitaliy and Chris can help us find more ways to stabilize the higher bit rate settings.
  • pls delete
  • I've been using Kae's 65MB/s 1080 24P 3 GOP setting for the past week including interview footage. The audio is in perfect sync.
  • @kae It plays back fine raw, and is ok in PP5.5 - try bringing it into FCP X (if you have it!) Note: That's no conversion to Prores selected and a straight import into a '1080p HD 23.98p' event. Can someone else confirm this is FCPX problem. cheers
  • @Ishvar;


    Waooo the GH2 VL is big?! ( minut 00:16 :-)
  • @Butt

    You really need to keep everything identical. The position of the camera changes too much to be a useful test. For example in the dog video one shot is much much closer to the dog than the other. The closer shot will give the appearance of much more detail. Also you need to focus manually and preferably use a pure manual focus lens so that the focus never changes between equivalent tests.
  • >You really need to keep everything identical. The position of the camera changes too much to be a useful test. For example in the dog video one shot is much much closer to the dog than the other. The closer shot will give the appearance of much more detail. Also you need to focus manually and preferably use a pure manual focus lens so that the focus never changes between equivalent tests.

    why do I?
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