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GH2 hack HDMI output testing
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  • Hi Dirk, Sorry I haven't answer earlier. I'm in the field and my access to internet is very limited.

    Again, you are right about the picture of the car.. I''ve used the Apple Color meter and 've focused in the reflexion in the rear left window. Is probably the area with higher light in the picture and is very little saturated. Almost white bluish. R235-G239-B254 (so Y239 Cb136 Cr124). If the RGB channels were wrongly patched to the YUV channels, as I thought, they would produce (up to the wonderful converter in the link you posted) an very vivid pink, no that orange midd luma triangle. Even assuming issues with white balance, RGB to YUV mapping or the fact that is an still of a TV screen, these colors are just crazy and i don't understand how they are generated. I'm lost. Back home I'll try to make some tests again using the GH2 and the NANO-flash HDMI. I'll try the Dell HDMI too and I will post some questions to the people of Convergent-design (NANO). I will ask them which kind of HDMI the NANO accepts and which kind puts out. Cheers

  • @GH2_fan It's a Y'Cb'Cr 4:2:0 8 bit signal that is fed to the HDMI out-converter of the GH2, to get converted to HDMI stream.

    This is what is needed to be done: I would love someone to find out for sure if the HDMI out stream itself is RGB or Y'CbCr, so I can understand why my screens don't work with the GH2 (PAL, 1080 HBR, live-view/record mode).

  • i'm in the same boat as @DirkVoorhoeve - no live preview in rec/live view mode in PAL with my 2 computer monitors with hdmi-ins, nor when connected to my steadicam 5.6" monitor through BlackMagic HDMI-SDI or through some ebay hdmi->phono converter. i'm pretty pissed, because the live preview was the only reason i replaced my gh1... and now still cannot make any use of it ;/

    of course it works fine in NTSC and in PAL when in playback mode.

  • @redpaw what type of cables/mini-adapter are you using. I ask because I had to purchase 3 or 4 mini adapters and 3 cables .. cheap locally bought before I found one that worked with any camera I have (Sony Canon and Panasonic). I do not know the reason, I assume some HDMI specification,

  • @kavadni that's very interesting. I will get myself another cable then, maybe it helps :) What type of cable do you have that works?

  • @kavadni it's a standard mini hdmi->hdmi cable. got 2 actually - one 1m and 1 that's 15-20cm long. no luck with either of them. in your case what it not working ONLY in live/rec mode... and then working in ALL modes with the 'good' cable? or you didnt get anything with the 'shitty' cable?

  • I can give anecdotal it was awhile ago. I have always been in PAL mode.

    I feed HDMI to a SmallHD DP6 Monitor, and my 40inch Samsung TV.

    The DP6 has a HDMI 1.3a and the TV a 1.4.

    When my DP6 arrived, I had my GH2 but it would not output to the TV, and I was in the heat of returning cables/adapters to shops .. getting frustrated .. wondering if camera was dud.

    It was recording and playing back 50i but no liveview. With PAL my priority at this point I didn't test 24p.

    The DP6 arrived with my first mini->standard cable a 1.3a. Connecting this from GH2 to TV worked.

    I later managed to get a mini-> standard adapter that works also.

    As everything I needed was now working, I did not perform any further tests.

    The only speculation I had was that my TV some how senses if a 1.4 cable is connected .. but not carrying any information .. or something .. the GH2 is 1.3a (I think .. without checking). That's just speculation. I concluded that in my case was definetely cable issue.

    Or specific to my TV, perhaps, as I do not have a mini->standard that is not 1.3a I can not test against the DP6

    Since then with my TV, I have made sure I make the connecting cable match the input device spec.

    I think my issue was similar to yours. It's anecdotal but from memory it's similar.

    I have been buying additional cables from smallHD .. they are cheap .. if you email them they have a cheaper freight option for accessory orders.

  • @kavadni so what you're saying is that there was no preview on the tv with 1.4 hmdi cable but it was working with 1.3a ? or did you just have some random unknown version of cable before the smallhd arrived?

  • @kavadni @redpaw. It seems like a long shot, but i've ordered the smallHD cable, so i'll let you know in a few days.

  • @DirkVoorhoeve cool! will keep my fingers crossed! ;]

    after a bit of research it actually looks promising... it might be the cables... if you have a look here:
    there are standard speed and high speed cables (ignore the Ethernet versions etc...)
    the standard speed one supports 720p / 1080i and the high speed 1080p, which might be the case. unfortunately unless the producer specifies it there's no way to tell them apart ;/ i'll do a little trip around the shops today to see if i can find any.

    also looks like changing the cables helped to more people then just kavadni

  • @redpaw tested it with the cable I got from smallHD... doesn't help. Still the same (playback mode is fine, record mode is not).

    I would say it is not a cadance problem as they say (i've tested in every PAL mode, NTSC is fine) and also not a 1080p mode thing as I am pretty sure that the camera outputs 1080PsF signal when in HBR mode. So the standard speed cables should also be fine.

    Did you get any luck yet?

  • Nope. bu ordered one 'high speed' cable hoping that will help... but after reading your post i'm not that optimistic ;/ One thing tho - i plugged it to samsung tv via hdmi and it worked fine (saying it's getting 1080i50 signal) but it wont work plugged into samsung monitor. loosing my mind ;/

    should get the cable any day and will let you know if that helps.

  • For anyone having trouble with hdmi cables, the one that came with my Zacuto snap works not perfectly. It is a swivel, which is not cool and did not come in handy with the ports being on the opposite side. I went through a couple before trying this one. Hopefully it helps.

  • so i got my high speed hdmi cable today.... checked it... and no luck. still no live preview in PAL. playback and NTSC works fine as it has before ;/

  • Just for the record GH2_fan the HV30 does not output 2048x1056 over hdmi.

  • @redpaw, I tried several nameless cables claiming high speed .. 1.4 .. etc, varying in price from $10 to $85 (I had no problem taking them back for refund, I just took the GH2 in with me) .. I gave up for a week or two assuming it was my TV .. my SmallHD DP6 arrived with it's cables .. they worked for me with both my TV which is 1.4a and the DP6 which is 1.3a .. I enquired with smallHD and they told me that their cables were 1.3a. For me that was the end of it. I tried plugging GH2 in at another person's place, with their cable .. big shiny blue thing ,, super fast 1.4a etc etc .. it didn't work. It's anecdotal that's all I can offer.

    @DirkVoorhoeve .. have you tried anybody else's televisions?

  • @kavadni yes it works fine on my TV and on my wondlan 7" screen. But not on the BenQ screens (I have two of them). So for me the SmallHD cable wasn't the solution, unfortunately.

  • @kavadni , @DirkVoorhoeve - so, i did more testing today... plugged the camera into professional sony field monitor (with bnc inputs)... used hdmi to composite adapter ( ) and blackmagic hdmi to sdi.
    blackmagic didnt work at all, but i presume its because its outputting sdi but the sony couldnt take it. anyway, using the ebay converter was the same story - works in ntsc and in pal-playback, but not in pal-preview/rec. adapter can output pal or ntsc (there's a switch in there) - and if camera is set to ntsc you can siwtch from pal to ntsc on the adapter and it still works, so the monitor takes pal and ntsc no problem. but switching back to pal doesnt work at all, no matter what is set on the adapter. then i tried samsung 42" tv: camera straight into tv works fine in ALL modes! (tv shows 1080i50).
    tried the ebay adapter and back to square one - works in ntsc, doesnt work in pal. which worries me, because i need to use this adapter for the steadicam... and then no matter if the monitor works with he camera or not, signal going through the adapter work work ;/ that's definitely something wrong with the camera... but why... and what?!

  • On the GH2 it is really annoying trying to get lighting and focus right on a large monitor through the HDMI preview mode (before pushing record). As it shows a low light low resolution picture until the record button is pushed then it is crisp. I may wish to setup the lighting a day before a shoot for a whole day and you continually need to have the crisp preview for many reasons otherwise you can really screw up shots. I used to have a consumer canon vixia hg20 (it gave me hdmi out clean) which I shot a film with and got better result as it is all about getting the picture right on the day. You can only do limited lighting in editing.

    I think a full resolution preview through HDMI should be a priority fix. Not so much to record from but to see what you are doing on set! trust me you do not want to shoot a feature film of a tiny flip screen!

    I have serious doubts weather to use this camera for my next feature. Any work arounds or fixes anyone know of?

    Cheers James

    p.s actually a good alternative would be a hack to be able to select a high bit rate codec then a low bit rate (so can record all day) for the HDMI preiews. I'll look around. Let me know if one finds one:)

  • I tried older dell 24" 2405. It works in play. No live view.

  • @jameshow73 - are you sure it's not caused by the 'constant preview' setting being set to OFF ? if its OFF and the image is too dark the camera raises the gain so you can see it. if you set it to ON then the exposure on the lcd/monitor is exactly as it's being recorded.

  • @redpaw - thanks for the comment redpaw, yes 'constant preview' ON. It seems muddier in preview like it is bumped down a few stops with more grain then when i press record it flashes a bright frame then records brighter (up a stop or so) and flatter with no grain. As far as I can gather everything is manual, I'll recheck all the settings. I hope it is a settings thing:)

  • I just did some pretty thorough testing, and my conclusion is the hdmi output is worthless for anything involving luma, chroma, or really anything other than focus. The only thing that ISN'T modified and accurate out of the hdmi output is sharpness.

    As james has discovered, the hdmi output is horribly inaccurate when the camera is not actively recording. The gamma is way, way off, blacks are crushed to death. When you hit record, the hdmi output cleans up a little bit, and the gamma gets closer to what is actually being recorded, but it's still off by a bit.

    I have two identical professionally calibrated and color managed monitors sitting next to eachother calibrated to the rec.709 color space and gamma response. I put the gh2 on a tripod pointing at a little set-up scene. I recorded a couple second clip, and using Scratch, displayed the clip on one monitor, making sure any LUTs or vcgt's that would be effecting output were turned off. Just the raw clip, as recorded, being displayed.

    I then connected the gh2's output to the other monitor. The difference between the recorded clip being displayed and the gh2's hdmi output was absolutely huge, and ugly, while the gh2 was not recording. When you hit record, it definitely cleans up a bit better and the gamma comes back up a bit, blacks are a bit closer to where they should be, but when you have the two side by side, even when it is recording the gamma response is totally not correct, and there is horrible green shift going on, and reds seem a bit shifted hue wise.

    Tomorrow I'll bust out the colorimeter and Calman, record some stuff directly off the hdmi output, and see exactly what the differences are, and get some pictures of the differences, but after spending a couple hours testing this my idea of even using the hdmi port for simple monitoring/waveform is way out of the question. Let alone using the hdmi output to RECORD! NO WAY!

  • I've also noticed the gh2 completely refuses to lock on and feed a signal to a dvi display using a simple hdmi to dvi connector. It will only work when directly connected to an hdmi port. I've used tens and tens of hdmi devices connected to my tvlogic using an hdmi to dvi connector, and none have complained, Was rather sad when I discovered the gh2 acted like it's not plugged into anything. Tried all hdmi output resolutions, no difference.

  • That calman sounds interesting Fohdeesha I'll give that a go. I have been searching for some windows 7 software for my Blackmagic Intensity Shuttle like Waveform and Vector scope but with no luck. But if hdmi is stuffed there is no point. I guess I'll have to literally shoot something, take the card out and check it on the computer through premiere pro waveforms etc. to check lighting.

    Perhaps the hacks make up for the guess work on set. Its just that I have spent 2 years fixing a feature film that took 2 weeks to shoot.