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Official Low GOP topic, series 2
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  • @rsquires I saw this earlier today, great looking clip, creepy baby things lol
  • Does anyone have a suggestion to a patch that handles high speeds? I am doing some aerial work from a Cessna Air Plane. Today on a teat run, Driftwood's 176 GOP 1 did not quite handle the high speed. I am running a Sandisk Extreme Pro 45mbts. Could that be the issue?
  • @Driftwood
    What its the best version of your GOP1 patches in terms of stability: quantmebaby, gopstoppa or smackmygopup?
    Thanks you. You are vary famous here in spanish forums with your spectacular Intra patches
  • @driftwood (or another expert around here)
    Can you tell me what the FB1, FB2, FL values do? Have you (or someone else) determined their maximum values? I get a very nice stream that crashes after 49 seconds and when I calculate the avg frame, it is about equal to the frame buffer size that is set. Is there a way to enlarge the buffer? At what point is the buffer cleared? Is there a setting for that?
  • I have no problem with the gopstoppa patch using sandisk and transcend class 10 16gb cards. I have had recording problems using a kingston ultimate class 10 100x 16gb card though. Overall, gopstoppa has been very stable for me, I haven't tried the other two.
  • Thanks inhousegoods
  • @ouzel The Sandisk Extreme Pro 45mbts is too fast for the GH2. It is a hardware limitation of the camera I believe. Stick to 20mbs or 30mbs and you should be fine. I am using Driftwoods "QuantMeBaby" and it works on a 16Gb Sandisk Extreme at 20mbs, that's an old class 6! Movies on it when converted to ProRes in FCPX are showing averages of 112.00 Mbit/s. They are 1920x1080.
  • @sohus Let me tell you where we're at. Frame buffers in theory can be enlarged or reduced to control the size of i, p or b frames. The problem is getting it right with the amount of bitrate to the video buffer size, and obviously to the quality setting as set by the AQ or manual IQ and Q settings. Its not so bad on zero AQ (or default - everything unchecked - its the same as AQ0 just about) and AQ1 then you have more freedom to adjust the FBs and frame limit. But it still takes time to get it right. 176M with a VBuffer on 36000000 at around a QP (quantiser parameter) of 14 seems to be the optimum point with my tireless testing. Going over AQ1 to AQ2/3 the QP changes quite largely;-
    Quantiser Parameters
    Default or AQ0 = AQ or IQ / Q left unchecked = 20 giving max/min QP+-2 from 20 (18 to 22) QP. average qlty, great for movement.
    if you set AQ to;-
    AQ1 = Initial Q will equal 20 when it is unchecked, and min QP of 14, max QP of 18 - good for movement, ok image quality.
    AQ2 = Initial Q will equal 20 when it is unchecked, and min QP of 9, max QP of 22, great all round balance.
    AQ3 or 4 will lower the min QP even more towards quality.
    Of course, everything then uses more bitrate - the better the AQ or the lower you manually set IQ and Q the more bitrate is needed to handle the better quality macroblocks.
    There are many variables to keep looking at but we are definitely very near peak stable control with the current 176M settings.
    At the moment Im trying ways of lowering the bitrate and pushing quality even more, and of course, lowering frame buffers has a similar effect on lowering the limits. Small increments/decrements (even with the step rule of testing) with each test means its gonna take a lot of time to reach a result.
    I am of course looking at other areas to adjust stabilisation. For example the Limit 63000 and the other limits can help adjust the initial cpb delay time - which always must be under 1 second (0.53 to 0.70 seems to be the stable area) - to help keep new settings stable.
    There are some strange things happening with the encoder settings too - which I can't comment on till Ive finished going thru about a weeks worth of possibilities - perhaps more. Who knows we may discover new findings soon. :-)
    At the moment many tests on GOP1 show that anything around 828,000 sized i frames will cause the encoder to stop recording after about 3 seconds on the various death charts. If you decide to use higher unstable settings in real scenarious you'll probably never get to crash the codec or get to that high i frame size unless youre filming massively high detailed trees of death, chandeliers :-) etc... Anyways, HenryO seems to love unstable settings (dig dig!) so push the frame limit back up to a higher size if you need to ;-)

    Sohus, so in an effort to answer your question its a case of continual testing and keep trying to balance all the settings within reasonable parameters. HenryO gets his 'Holy Fail' patch to short bursts of good quality by multiplying the FBs and limit by 4. However, you dont need to do that, you can get similar results just by adding smaller bits to the settings.
  • The SDHC/SDXC card test wont appear here until I get all the cards in. Chasing PR people to get evals seems to take longer than expected :-( However, good 'clean' type 10 cards from Sandisk, Transcend and Kingston at 20M or 30M (non UH-I) are perfectly ok to use with Driftwood settings.
  • Well put together driftwood, thanks
  • @driftwood
    Can you create a couple custom GOP1 patch settings to test the capabilities of the new SanDisk 95MB/s UHS-1 cards?

    I assume several of us are going to get our hands on them next 2 weeks,
    and would love to get you early feedback on stability at higher GOP1 settings.

    If they don't work well initially or show little IQ improvement,
    at least we could return them...


  • @driftwood
    Great instruction!
  • @driftwood
    Do I read correctly that your "smoothasF***" and "quantmebaby" setting work ok with Transcend Class 10 cards?
    I just started playing with quantmebaby using my Class 10 card and it seems to work although I don't think I've shot anything that stresses it. I did fill 15GB's by having it continuous record my HDTV and it spanned all 4 files.
    Thank you for all your work and look forward to seeing your card test.
  • Thanks @Driftwood. Another question:

    Your GOP 1 has a constant 800k quality
    If you make the iFrame larger, the P/B frames need to be reduced in size
    What would be desirable P/B frames with an I frame of 1,170? How will the quality differ from your constant 800K. In which situations (i.e. bright outdoor, static shots) do you notice an increased quality because of higher iframe, and when is there a disadvantage (probably low-light/dark scenes).

    The ultimate setting of course would be 1,170K constant iFrame. But as I mentioned before, I see all settings max out at an average setting of around 820-840k (avg framerate). It really looks like a buffer issue. I have had higher sustained bitrates but the stream crashes within a minute on those.

    I want to determine if, at all, it makes sense to have a higher iFrame setting with lower p/b settings at a 154M bitrate.

  • Well since GOP1 doesnt have p/b frames Im taking it youre talking about GOP3 154M? p and b frames require less memory and not such a bottleneck as the GOP1. I guess 154 GOP3 tuned up could bring 900k to 1M i frames but for how long you have to keep testing. The videobuffer is close to max on GOP1. There's a reason why we can't go higher than 265M on the bitrate too. It just can't handle it.
  • @driftwood is it cards that cant handle it or the camera itself?
  • Hi there, I'm not sure if this is the right place to ask this so please forgive me if it's not. I'm curious to know whether we will ever be able to see 4:2:2 with the Quantmebaby GOP1 Driftwood Patch? If not is there a good way to upscale the 4:2:0 to 4:2:2 in post? I read somewhere online about some methods to upscale using vegas, noise reduction, then add noise and then import to AE at 10/12 bit then re-export out.

    Any more advice?

    Thanks
  • there really is no way to change 4:2:0 to 4:2:2 you cant add color detail in post if it wasnt created from the get go
  • @PerryWilson A bit of both. The camera's video buffer is constantly full on GOP1 176M at around 80%, could well be be with these settings its at the max. However, if the clearing of frames from memory to SD could be increased (write speed) to a faster speed it certainly would help. I can record higher i frames for 7-10 seconds at peak buffer fullness without underuns or overflows but it just stops. It really might be down to write speed... we keep testing :-)
  • @driftwood, do you think your 244mbit GOP1 held more detail than QuantMeBaby?
  • A long time ago without new patches... What happened with the new GOP1 Driftwood's releases and similar promises...
    I can't wait for it -)
  • Just had a shocking moment. We shot this morning with driftwood's 176 gop 1, then rewrapped the AVCHD to quicktime H264. Now, with a little time to rough cut a bit, I started transcoding the AVCHD to ProRes (we're still on FCP7). I just looked to see the size, and the ProRes files are all SMALLER than the AVCHD. We're throwing bits away.

    I'll now start transcoding to ProRes HQ... but man this was a shock to see. Viva driftwood!!!

    Edit: Yup, the ProRes HQ files are matching the look of the AVCHD original, the ProRes is NOT. I need to sit down... wait, I am sitting down...
  • Driftwood 176 v3 in black & white...plus other "curiosities."

  • Captivating Hallvalla....
  • @Rambo

    Thanks - appreciate it.
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