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GH2 hack HDMI output testing
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  • ->Firmware 1.1 changes nothing with HDMI. Same as before.

    @Ralph_B With version 1.1 it's able to record at 25/30p in addition to 24p and 60i in camera while using HDMI. With the previous version it was only possible to record in 24p or 60i. 720p still doesn't work.

  • 25p will be sent as PsF over HDMI in PAL – clean cadence, other than 24p.

  • @Ralph_B

    Yes, I know. But his question concerned the in-camera recording when an HDMI monitor was plugged in.

    Yes, I'm talking about in-camera recording while HDMI is being used also.

  • @Rafa are you sure the cam outputs RGB? @DisneyToy could it be a color space problem?

    I have two BenQ W2400 DVI screens with HDMI output, and they will not give me any signal with my GH2 in live-view or recording mode. If I connect it through my Wondlan 7" screen it does display a picture, with blacks being magenta (R128,G16,B128) and white being green (R128,G235,B128). This is corresponding to the original Y'CbCr values of black (16,128,128) and white (235,128,128), if I understand color spaces correctly.

    I understood that for HDMI v1.1 and up RGB888 support is mandatory and Y'CbCr 4:2:2 is optional, and that the source device (GH2) should 'handshake' with the sink device (BenQ) to ask it's E-EDID to learn what audio/video formats it supports. Am I correct?

    Could it be that the GH2 only outputs Y'CbCr over HDMI, not RGB?

    update: If I set the camera in NTSC mode, the live-mode and record output to my BenQ W2400 screens is fine (the screen reports 1080i60). But in PAL mode it's only showing me a blue screen, like there is no signal. When I attach my other 25p camera to the screen it is fine (both 1080i50 and 1080p25 source). When I enter the playback menu on the GH2 the screens (both PAL and NTSC) also displays a signal.

  • Yes, I think so, it's only Y'Cb'Cr'. Many devices don't cover the "standard" to full extent.

  • Really? I thought someone here already discovered why we cannot get pure HDMI. Is it the hardware? What is needed to be done?

  • @DirkVoorhoeve . Sorry, I was traveling and I couldn't post you. You are very right on your considerations about color spaces and the chroma components values for Magenta and Green too. Also on how the RGB and YCbCr are patched (Y/G, Cb/B, Cr/R).

    I reached the conclusion that the GH2's HDMI was RGB for the fact that when I feed my PANASONIC Plasma TV with any HDMI/YCbCr signal out of the AJA ioHD (HDMI out RGB/YCbCr selectable) everything goes wrong. That makes me think that the PANA TV doesn't accepts HDMI/YCbCr but only HDMI/RGB. If this is true, the GH2 HDMI out should be RGB, because looks great in the PANA TV.

    My Dell US24 screen also display the GH2 HDMI without any problem. I doubt very much that is fitted to take HDMI/YCbCr (as you mentioned that's is optional and very little likely in a 4 years old computer monitor). Anyway, I will test feeding it with a HDMI/YCbCr from the AJA and I will post.

    Yeap. I've just found a pict of a test I did. In the left is the TV screen when the AJAs HDMI is putting out RGB. In the right when putting out YUV:

    Car.jpg
    1200 x 450 - 210K
  • So, is it a NO-NO case for clean HDMI output for GH2 when it is hacked?

  • @kicap In mi test (PAL), the HDMI is putting out a clean signal (full range, which is great), but interlaced (1080i25). For those who want interlaced, perfect. For my self who want Progressive, no.

    That's nothing related with the camera being hacked or not.

  • @Rafa yes I understand what you meant. But I am just curious on how possible to use the GH2 while it is hacked and sending a clean "progressive" HDMI output. All it seems to be in interlaced and I also don't like it. The AvySync that was used previously by some people doesn't seem to be sending a clear signal too. And it is not 4,2,2 also.

  • @kicap I understand you. When the GH2 is recording is sending a signal already processed (Video range/color matrix) and also interlaced. I think, being high quality patches, thats no worth to try to record it on an external device. The weird thing for me is the Interlacing issue. Its seems that even when set in p25 or p30, the camera always scan interlaced. I don't know who get the recorded signal progressive, but in many cases (even with the best patches) it fails and can not hide the original Interlacing (see some posts about banding).

  • @Nomad thanks for your quick reply. The interesting thing is, that I do get a good signal to my BenQ when the GH2 is in playback mode (screen reports 1080i50). And it also is working fine in live-view/record mode if I set the camera to NTSC instead of PAL (screen reports 1080i60). Would it be outputting RGB when in playback mode (PAL) or NTSC mode (playback and record mode)?

    @Rafa Nomad and Ralph_B say that the HDMI out is 25PsF (meaning: 25p in a 50i stream) when GH2 is in 25p recording mode (firmware v1.1). How did you find it to be only 1080i instead of PsF? As you wrote earlier that you tested it to be RGB888, which also is not the same as Nomad is saying (he says it is Y'CbCr). So, how did you test these things to be sure of it?

    @kicap You are saying that the HDMI out it is not 4:2:2, I guess you mean it is 8 bit 4:2:0 (like the AVCHD files)? If the HDMI out is Y'CbCr it will be a 4:2:2 stream as the HDMI specs do not allow 4:2:0. If it is RGB, then there is no chroma subsampling as Rafa mentioned before.

    To sum up for others, who are new to this game, what is for sure:

    • Yes: The HDMI out will be an uncompressed video stream, as HDMI specs do not allow compressed video. All these people talking about 'uncompressed' was very confusing to me, as if there also was 'compressed' HDMI. Compressed HDMI does not exist, as far I understand. What this discussion about uncompressed really is about is not the HDMI stream itself (which for sure is uncompressed), but the signal that is fed to the HDMI converter inside of the GH2. With the camera in playback mode, the compressed AVCHD video is decoded to an uncompressed HDMI stream, but the encoding artifacts will still be visible.

    • Yes: it is a 'clean' or 'clear' HDMI output: there is no information overlay on the HDMI out when you are recording., so it is a YES-YES case for clean HDMI output for GH2 when it is hacked.

    So, lets assume (among other things like the gamma shift, chroma bleed, interlaced chroma and/or compression, cadence, ETC and 720p mode) the real question is (as mentioned before by @Zincoontrin): what is fed to the HDMI converter inside of the GH2? Is this the same signal as fed to the AVCHD converter? Things changed a little after the v1.1 firmware (7/12/2011), so let's find out!

    First things first, I would like to be sure about two things regarding HDMI out:

    • is it RGB or Y'CbCr out?

    • is it 25PsF or 50i?

    This is: when recording in Creative Movie Mode - HBR 25 Progressive with firmware version 1.1 (7/12/2011), without any Ptools patches applied. So not in playback or live-view mode, no high bitrate patches, no 720p or MJPEG, no ETC. Best would be if someone has some way to analyse the HDMI output? So we can stop guessing.

  • @DirkVoorhoeve It's been done a long time ago. You're a little late to the party.

  • @Ralph_B thank you for pointing me to the link of your final avisynth script! As I understand from your post you also found the HDMI out to be 25PsF. But @Rafa said it is interlaced, so I am confused.

    After spitting through those 62 pages from your link to look for color space of the HDMI out I can only find details about color space conversion during recording, playback or transcoding. But my first question was intended for troubleshooting those not-working HDMI displays that are sometimes reported: what is the original color space of the HDMI out (when in record mode, HBR 25 Progressive)? Is it RGB or Y'CbCr? I can't find the answer (yet).

  • @DirkVoorhoeve Mine are speculations based in what I see on my TV (haven't checked yet on the Dell). If my TV breaks the HDMI/YUV from the AJA (see the picture in my post of the 12th) but plays well his HDMI/RGB and the GH2 HDMI, I have to deduce that the GH2 HDMI is RGB. That, or the AJA is lying me.

    This for me makes sense as well because when not recording (the AVCHD processor is not working, so no need of YUV nowhere), is easier to pull an RGB signal than an YUV signal from the system. RGB out simplify the things.

    About Interlacing/progressive, what I've found is that is plain interlaced: Two fields. I tried that with recording on the NANO-Flash. After deinterlacing the picture plays great on any progressive monitor.

    I've made my tests with the camera NOT recording because that gives a full 0-255 range. That's great, but the need to deinterlace isn't at all. When recording, the camera goes 16/239 clipping the highlights and apply the color matrix set in camera.

  • my experience I made with HDMI out without push the rec. button is that all movements (turning the camera or motions) have strange interlaced effects in progressive mode ( e.g. in after effects). In other words the video isn't perfect progressive. btw, I used black-magic Intensity shuttle. It seems Nano-Flash is working different?!

  • @Amadeus5D2 are talking about 25p (HBR mode)? You say it has strange interlaced effects, do you mean that it is 'sort of' PsF? How did you watch it?

    I'm am not sure, but I recall that Vitaliy has already pointed out somewhere that in PsF mode the Luma (Y') is sampled progressively (PsF), but the chroma subsampling is done interlaced. If I understand right, that's also the FixBrokenChromaUpsampling() part of the AviSynth script. Could that CUE-like effect be what you are seeing? In other words: do you still have those strange interlaced effects if you look at the Y' channel only (black&white)?

  • @DirkVoorhoeve "Yes: The HDMI out will be an uncompressed video stream, as HDMI specs do not allow compressed video. All these people talking about 'uncompressed' was very confusing to me, as if there also was 'compressed' HDMI. Compressed HDMI does not exist, as far I understand."

    If you play back internally recorded footage technically you are sending a compressed video stream out of the HDMI. Just like if you play a Blu-Ray movie thru HDMI to your TV it's compressed. It is entirely possible that the GH2's image goes thru some kind of compression before it streams out the HDMI.

  • @Brian202020 I fully agree with you, and I am sorry that I have not been clear in the original post. What I meant is that the HDMI stream for sure will be 4:2:2 Y'CbCr or better, but that it took me some time to find out that the real question is not about the stream itself, but to what is fed to the HDMI converter inside of the GH2? In case of playback it will for sure be the AVCHD video: but the output of the HDMI converter will not be a compressed stream, it will be decompressed before leaving the GH2. I'll change my post to be more specific.

    @Rafa I've been trying to get the same colors as your picture by using RGB->Y'CbCr or the Y'CbCr -> RGB conversion, but I could not recreate the colors in your picture. All I would get is a green/magenta haze like this, not all these strange colors you got, that looks more like a hue shift. And about the PsF v.s. interlaced discussion: Yes: the PsF stream will be two fields, as it is segmented frame. Try not deinterlace it, but instead set the field order to progressive. If it is real PsF, it should not look like this. Just make sure you have the cam in PAL -> HBR 25p mode. I'm interested to see your findings.

  • @DirkVoorhoeve You actually went through the entire thread? I'm impressed!

    If you're having trouble with a monitor not responding to the GH2's HDMI output, it may be because the monitor is expecting a 59.94i signal, but the GH2 is sending a 60.0i signal. Some monitors are smart enough to adjust, and some aren't.

  • @DirkVoorhoeve You say that the picture you are getting has all the colors in the Green/Magenta axe. So the colors go from (R128,G16,B128) to (R128,G16,B128), but the only variations are in "G" that goes from all 16 to 235. R and B always keep at 128 what means there is "0". For me that means that your monitor is getting a monochromatic (B&W) YUV signal. You know that in a B&W signal Y' will goes 16/235 but Cb = Cr = 128. So the R and B channels of your screen will always be getting 128, while the G channel (the one that get the Y' channel) can go all the way from 16 to 235. When the picture will be black (Y=16) you will get R128-G16-B128 (so Magenta) and when the picture will be white (Y=235) R128-G235-B128 (so green), when the picture will have a 50% luma (Y=128), you will get a grey: R128-G128-B128.

    The picture on the link you've posted is VERY BAD to judge this issue. That picture is not B&W but is very much desaturated. In the picture there are almost no reds, neither blues and even the green on the bushes is very weak. Chroma is low so Cb and Cr values won't go much faraway from "128". This makes that all the colors are very much close to the Green/magenta axe with little variations unperceptible to the eye, but I'm testing this with a Color Picker which is giving me the real RGB values on both images. The GREY makes sense because in the original picture is also gray.

    The picture I've posted have nothing of a color shift, but is a perfect example of what happens when you patch an YUV signal to an RGB system. If was a chroma shift, the low lights would change the tone, but would keep low lights because the luma wouldn't change. The same would happens with the high lights: would change the tones but would keep high lights. About pure Grays, they wouldn't change when shifting colors because they have no Chroma to shift. They would always remain the same. I have tried with Color Bars and the Black and the White bars change completely: A simple chroma shift wouldn't do so (I'll post later a test).

    If you see the picture of the car, there is not anymore low lights neither highlights. There you don't get the Greens or Magentas of your picture (neither a Grey) because there are not real blacks, whites or grey. There is color everywhere so you can't get Cb = Cr = 128 to produce these colors.

  • @Ralph_B I was also thinking it might be a framerate problem instead of a colorspace problem.

    But it works fine with the NTSC signal: the screens reports 1080i60 and displays the live-view/record as well as playback screens. So it is not the 1.001 / cadence / double frame NTSC problem.

    It also works fine with PAL in playback mode: the screens reports 1080i50 or 720p50 (depending on HDMI mode settings) and I can playback films on the screen. So the GH2 can output 1080i50 to my display.

    It only doesn't work in PAL live-view/record mode: the screen reports that there is no signal. I can get a signal though, when I attached it through my 7" screen, but the colors are all messed up. That's what got me to think it is a colorspace problem instead of framerate.

  • @Rafa I am with you on the part about the B&W signal, with all variations having Cb and Cr values of 128 and only Y' changing.

    But I must say I find it difficult to understand what is happening with your picture though. FYI I attached two pictures of my display. It is an image your picture, displayed on my BenQ and then photographed. Colors will not be exactly spot-on, but it will give you an idea of what I am seeing.

    gh2_to_benq.jpg
    790 x 299 - 66K
  • Hi again guys, sorry for popping this up again, but really may I ask, what is needed to be done? most likely to do with the hardware, does someone need to dissassemble it or something to discover this??