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Official Low GOP topic
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  • @all

    Just got back in town. 3.62d potential looks great! Huge thanks to V and C!!! I haven't found a way to get stable high data rate death charts yet with 3.62 and 3 GOP 24H. I tried playing with 66mb and triple fb but just produced unusable low data rate footage. I tried the old 65mb extreme settings and set aq to 2. Death chart footage was horrible. So am sticking with old 3.61 65mb settings until someone can point me to stable 60mb or above 3 GOP FSH settings.

    Also, I guess I don't understand the benefit of big B frames in 3 GOP. If the B frames refer to differences between it and the previous and next I frame and that I frame is just one B frame away in 3 GOP's case why would the B frames need to be huge? It seems to me in 3 GOP's case the I frame is the most important since it comes 8 times a second so the bigger the I frame the better. Or am I missing something technically here?

    I guess I'm looking for someone to get as high of stable data rates as those shown below (death chart on 65 extreme settings with 3.61). I'd even settle for a 60mb constant stream with 3 GOP - Is there a way with 3.62 yet? And please don't answer 'set GOP to 12 or 6', I'm interested in 3.
    kae65extremewith361ptoolsdeathchartA.JPG
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    kae65extremewith361ptoolsdeathchart.JPG
    1274 x 666 - 169K
  • I know you don't want to hear it but the low GOP doesn't work right - Vitaliy is working on it. We know what the problem is - it will just require a little time for him to work it out. Then, and only then will you get what you want. This is a little like trying to drive a car with a flat tire - it just doesn't work very well - no matter how much you want it to.

    Chris
  • @cbrandin

    Thanks, Chris! I was gone for awhile so trying to catch up. I'll quit testing the 3 gop settings then until it's fixed.
  • @kae "And please don't answer 'set GOP to 12 or 6', I'm interested in 3. "

    haha. me too. GOP 3 or lower... ;) I'm addicted to the blinky-sticatto film motion.

    I'm wondering why long-GOP was ever implemented. What good is higher quality if the motion suffers? Did they not see that it makes everything look like 360-degree open shutter?
  • @bwhitz
    Long GOP was invented for the same reason MPEG2- MPEG4- H246 etc was invented. (or part of really). As a way to distribute digital assets easily - at a low quality to fit on a DVD.

    They noticed that at the end of the day - most of the motion in video is still- so no need for a new frame every frame! I think that most professional mastering houses (probably not now) used to put in markers to let the encoder know when was the best time to put in more I frames as opposed to B, P frames. (car chases etc).

    And without Long-GOP even 25gig wouldn't really be enough for a Blu-ray really anyway... but that is not where the industry is at right now anyway. I believe currently the industry is still trying to work out online distro- and making money online- and what the F$*K they are going to do with 3D now that they have it...
  • what would be a low gop settings using ptool 3.62 for gh1
  • loaded my GH1 using ptool 3.62 with transcend class 10 card and i have gop1 at FH 88000000 and 55000000 H am hitting 50mbps bitrate indoors and no problem so far, will test outdoors
  • tested 65 3 gop vs 44 6 gop Kae settings, drummer hands, we could see the differense in motion blur, 3Gop having more film like.
  • Tried the new ptools 3.62, and because of the weird short GOP problems am sticking to the old ptools Kae settings. Got some wonderful speedboat / water shots using kaes 3GOP. Any news on when the GOP fix is coming? Tried out a few 1 GOP settings and same problem Kae was getting with his latest 3GOP test - low bitrate.
  • @driftwood "Tried the new ptools 3.62, and because of the weird short GOP problems am sticking to the old ptools Kae settings."

    +1 me too. These settings are great! The only thing that could top them would be GOP-1. The motion just looks too good to me to raise the GOP. I heard they were trying GOP-24 in another thread! What!!! Just take still pictures and animate them in after effects at that point! I don't get it! High-GOP motion looks like Flash animation.

    Also, with Kae's extreme settings sometimes I get a weird bug where the camera will tell me that it can't play back the file... but then once I record another clip, it'll play back fine... anybody else getting something like this?
  • Hang on, Just tried my 36 GOP settings switching down to GOP 1 and got these amazing results.All intra frames, passed the Pappas chart of Death (still going after 2 minutes). Just what is wrong with the 3.62 GOP settings Chris/Vitaliy? Kae/Anyone try my settings out for me to confirm. Is 50mbps the sweet spot?
    Chart below were taken on pappas death chart btw.
    Also shot 5 minutes of footage and got nice looking images. Nice staccato!
    Short GOP 1 - 50bitrate test using ptools 3.62 .png
    1312 x 704 - 88K
    Short GOP 1 - streamparser time mode - 50bitrate test using ptools 3.62 .png
    1306 x 695 - 80K
    Driftwood GOP1 50mbps - setb.zip
    411B
  • @driftwood

    Great stuff! I hope to try these out tonight! I'll let you know what I find...

    You're using these setting with Ptools 3.62 right?
  • Average I-frame size little over 2MB. Are you sure it's big enough to capture highly detailed scene?
  • @stonebat

    1920x1080 420 raw frame=2073600+2*518400=3110400 bytes
    I Frame size here = about 268000 bytes.
    Only 1:11 compression (and I frame compression in H264 is more effective than JPEG).
  • Oh I meant 2Mb I-frame size.

    1:11.6 compression...
  • @driftwood - could you please post your GOP1 settings as an .ini?

    I'd love to test this.
  • @bannedindv He did, look to the far right of the two images - download the zip file...
  • @driftwood Can you upload the clip(s) to Vimeo or something?
  • oh duh - I had to log in to see that. Thanks.
  • :)- Its hard to see cause its white like b-ground even I didn't see it at first.
  • I tried GOP12. I-frame averaging 8Mb. 1:3 compression. NLE was much easier than clips from unhacked body.

    I guess... 1:11 compression would need transcoding? @driftwood can you edit the clips easily without transcoding?
  • ProRes422 1080p24 bitrate for 10bit 422 (not HQ) - 117Mbps
    http://www.appleinsider.com/articles/07/04/18/a_closer_look_at_apples_new_prores_422_video_format.html

    @stonebat
    Normally the lower the GOP - the faster is NLE :-)
    Compression do not matter much unless your disk or cpu are extra slow (in this case lower compression will be slower).
  • 100Mbps read throughput is non-issue for 7200 rpm hdd. 1:1 compression might run into disk read speed bottleneck.

    If HDMI recorder can record reliably at 117Mbps, 117/24 = 4.875Mb per I-frame at GOP1. But average write speed of 7200 rpm hdd is around 12MB/s or 96Mbps. Hmmm... the speed might go lower.

    If stable write at 117Mbps, 1:6 compression. Not bad. Actually that sounds pretty good if I-frame compression is better than JPEG's.
  • I cant wait to see some awesome GOP1 footage-



    Star Trek_ Simon Pegg as Scotty (rus subtitles).flv_000089000.jpg
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