GH2 RAW 4.2.2 HD Out?
- Thread starter yoclay
- Start date
Barry_Green
Moderator
Sounds like the GH2 outputs uncompressed 4:2:2. Nothing really new there, every consumer camcorder with an HDMI port does exactly the same thing.
I guess it's new to DSLR users, as they have weird limitations like dropping to SD during recording or whatever but... even a Canon HV20 does uncompressed HD on its HDMI port, so it's not really anything all that special.
The use of the term "raw" is what's confusing things. Raw has a very specific meaning, which is an unprocessed, direct copy of the sensor's output. No video camera does raw. All video cameras process their images, and then output it on their digital outputs. The difference is that it's not been compressed with the h.264 codec, so it's uncompressed, but uncompressed does not equate to raw.
You will never see actual "raw" output over an HD-SDI or HDMI port. Those mechanisms don't transport raw, they transport defined video signals.
I guess it's new to DSLR users, as they have weird limitations like dropping to SD during recording or whatever but... even a Canon HV20 does uncompressed HD on its HDMI port, so it's not really anything all that special.
The use of the term "raw" is what's confusing things. Raw has a very specific meaning, which is an unprocessed, direct copy of the sensor's output. No video camera does raw. All video cameras process their images, and then output it on their digital outputs. The difference is that it's not been compressed with the h.264 codec, so it's uncompressed, but uncompressed does not equate to raw.
You will never see actual "raw" output over an HD-SDI or HDMI port. Those mechanisms don't transport raw, they transport defined video signals.
Last edited:
Hunter Hampton
Carbonite Member
The "raw" does get misused like this. However, there is one camera I know of though that sends raw bayer data over dual-link hdsdi (arri d21 via T-link), quite rare of a use though I would guess, probably wont see another camera set-up to do that.
Certainly sounds like fiction. "RAW" HDMI output from GH2 or any other DSLR on the market is not the same RAW sensor output from a Red camera.
"RAW" HDMI data on your typical DSLR has already undergone quantization and chroma subsampling, both lossy compression methods. It does not undergo the third level of compression in an AVC encoder, but is still compressed from a purely imaging data point of view. And herein lies the distinction between "boys" and "men" of the camera world, amongst many other aspects.
Vitaliy Kiselev
Carbonite Member
Generally, 1080p RAW can be worse than 1080p HDMI "raw". As HDMI signal is result of debayer and rescaling from higher resolution, usually.
One may record to 10bit 4:2:2 Pro-Res, however the signal originates at 8-bit. A step forward this is, but turning point?
Origination in this context means the point at which HDMI signal is handed off to the Ninja. I'm 100% certain that signal is 8-bit. Because a consumer product will not upend the professional one costing 5x as much from the same parent company.
Well actually, it depends what hdmi standard they adopted and they could be using anything from 8bit to 12bit, so unless they declare it we dont know? plus it could very well be 12bit 422, there is no reason why they need to downgrade the hdmi processing it may of been built into the processing chip and there isnt anything they can do about it ie the firmware! if they support deep colour from the hdmi and all the manual says is vierra version 5 compatiable which goes all the way to version 1.3 hdmi, so it could be 12bit uncompressed output?
I don't understand.
I thought HDMI out is a stream of the sensor output? Why should it be 8 bit? Can someone explain me?
The stated reason for the commonly complained about lack of 10-bit HDMI or SDI output on AF100 was an 8-bit processing pipeline. With that assumption in mind its quite hard to believe that a product positioned in a lower market segment will have better capability in that regard.
HDMI 1.0 to HDMI 1.2a uses the CEA-861-B video standard, and HDMI 1.3+ uses the CEA-861-D video standard.[41] The CEA-861-D document defines the video timing requirements, discovery structures, and data transfer structure.[42] The color spaces that can be used by HDMI are ITU-R BT.601, ITU-R BT.709-5, and IEC 61966-2-4.[43] HDMI can encode the video in xvYCC 4:4:4 (8–16 bits per component), sRGB 4:4:4 (8–16 bits per component), YCbCr 4:4:4 (8–16 bits per component), or YCbCr 4:2:2 (8–12 bits per component).[43][44]
HDMI supports up to 8 channels of uncompressed audio at sample sizes of 16-bit, 20-bit, and 24-bit, with sample rates of 32 kHz, 44.1 kHz, 48 kHz, 88.2 kHz, 96 kHz, 176.4 kHz, and 192 kHz.[20][45] HDMI also supports any IEC 61937-compliant compressed audio stream, such as Dolby Digital and DTS, and up to 8 channels of one-bit DSD audio (used on Super Audio CDs) at rates up to four times that of Super Audio CD.[45] With version 1.3, HDMI supports lossless compressed audio streams Dolby TrueHD and DTS-HD Master Audio.[45]
As we know the sensor is 12 bit and everything hangs off that, raw photo files are 12 bit too, but the hdmi is defined by a specific standard and I am not sure unless Panasonic declares it that they will tell anybody what the actual bit rate structure is, howvever clever people like some of the guys on here may be able to work it out?
HDMI supports up to 8 channels of uncompressed audio at sample sizes of 16-bit, 20-bit, and 24-bit, with sample rates of 32 kHz, 44.1 kHz, 48 kHz, 88.2 kHz, 96 kHz, 176.4 kHz, and 192 kHz.[20][45] HDMI also supports any IEC 61937-compliant compressed audio stream, such as Dolby Digital and DTS, and up to 8 channels of one-bit DSD audio (used on Super Audio CDs) at rates up to four times that of Super Audio CD.[45] With version 1.3, HDMI supports lossless compressed audio streams Dolby TrueHD and DTS-HD Master Audio.[45]
As we know the sensor is 12 bit and everything hangs off that, raw photo files are 12 bit too, but the hdmi is defined by a specific standard and I am not sure unless Panasonic declares it that they will tell anybody what the actual bit rate structure is, howvever clever people like some of the guys on here may be able to work it out?
Emanuel
Cross-Examiner
Sure it is, as far as RAW your addendum concerns (despite the fact of the wider meaning of the word in english beyond its use in photography terms). DSLR users as well.
But the point is: if we have now a S35 DOF type (or alike) in a similar sensor size, not ever before with 4:2:2 output in whatever codec you can get with a portable acquisition device for less than $1,000 + $1,000... it is a dream became true, shared and predicted by people like Francis Ford Coppola more than two decades ago
Last edited:
philiplipetz
Veteran
In the discussion at Philipbloom.net Makoto posted the following where he says that Panasonic does not give a HDMI signal suitable for sustained video encoding.
"The HDMI live-view output is not suitable for recording use, using nanoFLASH or Ki pro, Ki pro mini, etc.. You will get one freezing image every 17 seconds. It happens because of the difference between 60 fps, which is the frame rate at which the sensor reads the light, and 59.94 fps, which is the frame rate of the HDMI output. This is the explanation I had from Panasonic.
"Although you can not use it for recording, I found it great that you can view the recording image at 1920 x 1080 resolution.The most beautiful thing about the new GH2 is that its image sensor reads at 60 fps. So, the 60i is a real 60(59.94)i and 60p, although at 1280 x 720, is a real 60(59.94)p. I am sure that you will do the slow motion by converting 60p to 30p soon, and you will see the difference. The 4/3 image sensor is smaller than EOS’s, but EOS’s image sensor can read only at 30fps."
"The HDMI live-view output is not suitable for recording use, using nanoFLASH or Ki pro, Ki pro mini, etc.. You will get one freezing image every 17 seconds. It happens because of the difference between 60 fps, which is the frame rate at which the sensor reads the light, and 59.94 fps, which is the frame rate of the HDMI output. This is the explanation I had from Panasonic.
"Although you can not use it for recording, I found it great that you can view the recording image at 1920 x 1080 resolution.The most beautiful thing about the new GH2 is that its image sensor reads at 60 fps. So, the 60i is a real 60(59.94)i and 60p, although at 1280 x 720, is a real 60(59.94)p. I am sure that you will do the slow motion by converting 60p to 30p soon, and you will see the difference. The 4/3 image sensor is smaller than EOS’s, but EOS’s image sensor can read only at 30fps."
Last edited:
No hack workaround?
Barry_Green
Moderator
HDMI is most definitely not a stream of the sensor output. The sensor outputs a raw, unprocessed, unvarnished, ugly-to-look-at, Bayer-pattern mess. That's called "raw". It has to undergo extensive processing to turn it into a lovely-to-look-at video signal. And as part of that process, it will be demosaic'd, the various gamma and picture profile settings will be applied, then it will be tuned into the HD-standard Rec709 color space, and subsampled to a video-signal 4:2:2 color sampling system, and quantized at either 8-bit or 10-bit (and, considering it's a $899 stills camera, my money is on it being 8-bit). Once all that processing is done, it is then output over the HDMI port.
The only difference between that, and what gets recorded, is the application of the AVCHD codec compression. Getting a live HDMI output of the uncompressed data means that it should be artifact-free and possibly 4:2:2 instead of 4:2:0.
So it's a step up, yes. But it's not revolutionary; like I said, every consumer HDV and AVCHD camcorder has been doing this for years. But it does seem new to the DSLR world, where the GH1 had no HDMI output whatsoever, and the Canons have some lower-res subsampled output, so in that context it's a big step up because it appears to make an external recorder a viable option.
LOL, NTSC strikes again. Even though analog 29.97i video broadcasting has been permanently shut down by FCC regulations, we're still saddled with its pernicious legacy. It's really way past time for ATSC to proactively set a final deadline for phasing out the endlessly error-prone muddle of NTSC bitrate discrepancies.
Death to 29.97!
Barry_Green
Moderator
Totally agree; there's only one product on the market under $8,000 that has a 10-bit pipeline (the EX1). I sincerely doubt that the GH2 will have it. But, hey, we'll see.
Barry_Green
Moderator
And death to all interlaced, too. Please.
I was profoundly disappointed that the ATSC and EBU couldn't work out a worldwide standard for HD between the two of them. So we're saddled with the 23.976/29.97/59.94 nonsense in NTSC land, and we're stuck with incompatible signals between NTSC and PAL even though we entered this glorious new HD age.
I say by all means, delete, destroy, and eliminate 29.97/59.94. The new standard should have been 24/25 and 50/60, all progressive, and prior 29.97 and 59.94 programming would just have to be sped up by 1/10th of 1%. No viewer would ever have noticed, but ... man, it would have returned sanity to the television landscape that disappeared six decades ago! (with the introduction of color, when they changed the USA television rate from 60.00 fields per second to 59.94).