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Can you lower bit rate to almost nothing?
  • JDNJDN

    I'm setting up ghs to film a duck nest, with hdmi out to a hyperdeck or ninja (can swap out drives without bothering birds). I know hdmi out on gh is only good when recording -- question is, has anyone tried lowering the bitrate below the factory presets? Want it to basically write crap to the card in L mode, but be able to do so for days on end, meanwhile getting the good stuff on the external recorder, which is a safe distance.

    If anyone has played with this, I'd really like to know. Thanks!!!

  • 21 Replies sorted by
  • jleojleo

    Flip HD Surveillance Camcorder records 40 hrs +

    http://www.amazon.com/Flip-DVR-Video-Surveillance-Camcorder/dp/B0084A1OW6

    May need ext power source.?

  • driftwooddriftwood

    Should be fine: Try setting an L/H/FH setting up to a really low bitrate (until it works)

  • Ralph_BRalph_B

    Just wait long enough and somebody's bound to ask just about anything! :) Yes, you can do it. Once when I was working on a patch, I accidentally left a zero out of the 24L bitrate, and I was wondering why the picture looked so crappy. Turns out it was recording at 6 mbps.

  • ZekoZeko

    with the hack, i think you can do anything to your bitrate.... problem, like @subco said, is battery life, which happens to be very low on GH's. (hint to panasonic, if you want to make a video-mirrorless, try giving it a camcorder battery, like being able to record 5 hours straight full hd)

  • JDNJDN

    Thanks all for the feedback. @subco I'll look into those cameras, but here's my plan:

    In a large pelican, far from the gh2, wire this adapator (http://www.switronix.com/news/204-switronix-releases-xp-cable-for-panasonic-lumix-gh2) to one of the large capacity d tap batteries I have. Run a long extension between this adaptor and the DC coupler, and run that out to a smaller pelican containing the gh2 (the HDMI and remote shutter will also be bundled with this wire -- I believe you can get about 50ft on HDMI before quality degrades or drops off entirely).

    Whenever I go to change the HDD on the ninja, I also swap out the swit batteries. If I set the bit rate on the gh2 to next to nothing with a 64 gig card (and ridiculously low bit rate), I should be able to record at least a few 16 hour days in a row before needing to go out to change the card (the birds we are dealing with, canvasback ducks, are incredible skittish and if disturbed too many times will simply abandon their nests).

    Plan is to use ninjas as they can run on HDDs not just SSDs so it will keep costs down. Realize gotta do the avisynth processing tho which is kinda bummer.

  • Ralph_BRalph_B

    @JDN

    As the author of the Avisynth script, I can tell you that it's going to take an insane amount of time to process files that long (possibly weeks in this case!). What I would suggest is to first review the footage, copy the sections that are useful, and then process those sections in Avisynth. That would definitely be doable.

  • peternappeternap

    Since you're not concerned with picture quality, why not just use a Reconyx set to field mode (Timelapse).

  • JDNJDN

    @Ralph_B thanks -- BTW, if I just shoot 1080i and then de interlace, would that be simpler? There's no sync, and no need to be in 23.976 for this one at least. Or are there problems with the hdmi output for that as well?

  • Ralph_BRalph_B

    @JDN

    1080i is definitely an option. I did extensive tests with it. Like 24P, it runs at a true 60.0i. This means every 13 seconds or so, the GH2 inserts a duplicate field. Truth be told, when you play it back, it goes by so quickly (1/60th of a second) that nobody's ever going to see it, especially for a static shot.

    You'll lose some vertical resolution by going interlace, but maybe it's worth it. On the otherhand, you're still going to have to spend time in post to deinterlace, so it's not going to be that much faster than using Avisynth to process 24P files (assuming you only process the relevant sections).

    Sounds like some pre-testing is in order :)

  • JDNJDN

    @Ralph_B thanks man -- 1080i it is! We'll just bring it into a 23.98 timeline later and de interlace (that's the nice thing about avid I suppose... mixed media no problem).

  • JDNJDN

    Hey everyone, just to close this one off for the moment are my findings of testing that I finally completed today:

    • No problems keeping a clean HDMI signal from the gh2 over 50ft of HDMI cable
    • The lowest that FH mode (1080i) can be lowered is to 4 mbps. This gives you a little over a full day of record time on a 64 gb card
    • so far have had no problems recording .mxf files on the hyperdeck, linking with media tool in avid and deinterlacing

    Haven't played around with the 24p output over 1080i and gh2's strange pulldown problems. Thanks again to all for the quick replies and the help.

  • driftwooddriftwood

    Good findings @JDN

  • JDNJDN

    I should also note I used factory firmware and only lowered the FH signal, keeping all others to presets. After this duck shoot wraps up, I hope to do some HD raw tests at 1080i with the hyperdeck and greenscreen. Will see if it performs any better than Sedna (I doubt it, but will be good to know!).

  • nomadnomad

    With the serious limitations of the HDMI output (8 bit and probably 4:2:0) the differences are negligible. I tested difference frames of full-frame moving leafs between an older version of Sir Driftwood's I-frame settings and a Ninja. They were near black as opposed to factory firmware which showed massive differences.

    IMHO, any external recording with the GH2 is a waste of time and money. Get the best SD cards and one of the best settings around here (according to your taste) and you won't see any difference.

  • JDNJDN

    @nomad, definitely can't say that external recording is better than @driftwood 's fine work, but on the hyperdeck (in 1080i30 w/de-interlace) it looks pretty comparable. Which is basically to confirm your point -- just buy 64 sdxc cards (I have 6 and counting I think).

    Nevertheless, do have to say that I"m happy with the hyperdeck for this (albeit highly specialized) purpose. The only real observation so far is that the hyperdeck seems pretty much grain free while patches have (pleasing to most eyes) grain.

    Been a very positive experience with the hyperdeck so far which makes me revisit some of my earlier opinions on the forthcoming camera. Although now that I own 4 x 512 ssds, I guess I can afford to.

  • duartixduartix

    @JDN While developing my Timebuster settings I remember getting around 2mbps on some tests of static footage. I also remember that a few quick calculations revealed that 3-4 days was perfectly achievable if the quality was further dropped but still within acceptable limits.

    I suggest you get the stock settings and change only this:

    • 1080i50 and 1080p24 GOP Size=50

    • Encoder setting 1 1080i/p=3

    • Quantizer for 1080 modes=32

    • 1080p24 Scaling I=0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF

    • 1080p24 Scaling B=0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF

    • 1080p24 Scaling P=0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF

    It's guaranteed to get you sh*t! ;) Probably a full week of it... :)

    P.S. Forgot the most important detail! Set the camera to MF and the shutter speed to 1/2s. The camera is only capturing 2fps of distinct content this way. Another thing I found out about this mode is that it increases battery life (probably because there's a lot less readout). :)

    P.S. 2 There is one inconvenient about this mode though: you'll probably run one battery flat before you find out if it spans. Not that it shouldn't! :D

  • duartixduartix

    Confirmed! http://www.personal-view.com/talks/discussion/comment/40297#Comment_40297

  • duartixduartix

    @PDN Sorry. You should try this instead:

    • 1080i50 and 1080p24 GOP Size=50

    • Encoder setting 1 1080i/p=2

    • Quantizer for 1080 modes=32

    • 1080p24 Scaling I=0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF

    • 1080p24 Scaling P=0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF

    There is no point in using B-Frames when trashed P-Frames take up a lot less space. I used encoder setting = 3 in my settings because it was the only way to make the Quantizer stick. In this case, I don't think it's necessary. I'm not even sure if the Quantizer setting will do anything because the Scaling tables are already doing a pretty good job of trashing I and P frames.

  • JDNJDN

    @duartix thanks! This is very helpful. We would like to be able to record to the hyperdecks for even longer without having to reformat the cards so this will be great to try.

    One question though: you suggested Manual Focus -- will it work with auto too? We need to keep the cams in AF because if they lose power, the focus by wire reverts to default and you lose your shot when you power it up again -- wheres the focus point (for whatever reason) doesn't revert to default on power loss but instead stays locked on whatever you selected previously, even when off center, small etc.

  • duartixduartix

    @JDN Let us know what bitrates you got. I'm curious... :)

    The patch will work in 24p (H and L) regardless of the Focus Mode. Stupid me! I suggested MF because you can't get shutter speeds below 1/25s without setting the camera to MF. I don't know why, but I got the impression that you were timelapsing which after all doesn't look like what you intend. Very slow shutter speeds are very conservative on battery power though...

    Isn't there an option where you tell the camera not to reset focus on power down? I don't have mine with me, but I remember such an option on my Olympus body.

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