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interceptor121

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  1. Thanks for your reply with ambient light I have zero issues with cine like D. I underexpose underwater around -2/3 (camera metering at zero gives rubbish results) then lift exposure and stretch blacks and whites in post increase saturation and works wonder. I white balance in water. However for deeper dives color are just lost as absorbed in water and there is less light I am just concerned cinelike may not work well at higher ISO but maybe am just worrying unnecessarily!!! At the end there is not much dynamic range due to environmental conditions so I though I would work in a rec709 format are the colors are not there anyway Maybe am worrying for nothing and should stick to my guns as it seems to work well
  2. Thanks Kye they are shot in 24p if that matters! So far I do not have the VLOG key I have tried HLG but it does get difficult in edit. I try to prepare as much as possible my settings before hitting the water as I need to get on a trip in order to dive with the camera so I am after some theoretical points that helps maximise the camera. Generally in conditions like those in the video is very bright at the same time I need to keep aperture between f/5.6 an f/11 so this means ISO ranges between 100 and 200. With this settings Cine Like works very nice I do not need anything more. My issue is what happens when am in the ISO 400-1000 region? Will cinelike D still do well or am I better off trying Log. Which one of those will give me less noise and allow me to shoot with the range of apertures I need? In theory VLOG starting at 400 seems a better candidate but I do not have enough experience as I do not have the VLOG to evaluate. Right now I have not felt the need to shoot in VLOG at all! So in theory the fact that VLOG clips at 85% should help with low light??
  3. Hi Everyone I finally managed to get my first short underwater clips with the GH5 And I am using Cine Like D and the results are pretty good. However those videos are with rich ambient light in other situation I need to go in deeper water and there will be less light I am wondering if VLOG is a better option. Dynamic range is not the issue there isn't a lot at depth but low noise is. I will be shooting with predominant artificial LED light Would love some theoritical pro and cons of Vlog vs Cine like D in this circumstances (optimise noise not range( Thank you
  4. They are two different things. An image can contain 24 bit different colours but they do not necessarily fit into the RGB 8 bits. You could have some in a gradation in between your level and some values completely missing hence it is important to capture higher bit colour sample 10 or 12 bits if you can even if you eventually you discard them later I think you have less understanding than you think you have I am not sure what a colour profile is maybe you are talking about a transfer matrix? The amount of information the sensor captures is nothing to do with what ends up after compression and if you squeeze information into a narrower colour space you have clipping. The GH5 uses BT709 and BT2020 and there is a difference between the two otherwise you would not have colours in HLG that clip in REC709. And your last comment on dynamic range out of the blue of a whole set of statements is rather interesting I rather have no further explanations if you don't mind thank you
  5. This table is useless as even if the codec is the same the compression settings differ that was the whole reason for my post
  6. The sensor is 12 bit and raw does not have a colour space the camera saves files with sensor data and metadata the processing is then done by a program that works in an intermediate color space for editing and correction and then outputs in RGB format on JPEG The fact that the camera can work in a colour space as wide as adobe rgb or rec.2020 does not mean it can resolve 10 bit colours a pixel may have 8 bit resolution with colours coming from a wider colour space but still not able to resolve 12 bits on a single image even a DSLR with a 14 bit sensor stops at 26 bits which is 8 and 1/2 bits and in most cases there is no additional info between 12 and 14 bits RAW in terms of colour or resolution
  7. I record underwater video the housing for the atomos costs $3000 plus the recorder cost so I am not planning to buy it V90 cards are much more affordable in that context Am not planning to shoot LOG either as underwater there may be quite a bit of noise and everyone who has tried even prores HQ has had poor results So my plan is currently cinelike D I need to decide between 8 and 10 bits and if I go all intra Generally All Intra should save me some time as my workstation is not strong enough to process h264 real time so I would need to convert to ProRes 422 for what concerns your comment on dxomark enlightened me please raw images do not have a colour space concept so those are tonalities that may or not fit in a video colour space but it is unlikely they will all fit into REC709 if you were shooting HLG you coild have deep colours I don’t know what transfer matrix LOG footage uses but am not planning to shoot LOG regardless best case I would shoot HLG on land but that eould require monitors etc
  8. I am not unhappy with the camera I was just expecting more out of the 422 10 bit mode as I am not planning to buy a recorder and I was hoping not to need V90 cards From what I can see with my naked eye footage straight out the camera without LOG looks better in 8 bit mode than it does in 10 bit I play it straight out of my Tv that has a 10 bit panel. I cannot see any benefit of 422 or additional colour using cinelike in the rec709 colour space compared to 420 8 bit. I white balance all my clips on a grey card so they are generally not off and look good at the outset. I do not use log at all and this is another form of compression that uses metadata and what comes out depend on many other factors. the considerations I have made are purely technical and generally are useless to compare different cameras but hold pretty well when you compare codecs offered by that same camera. The considerations are objective and not subjective and when looking at interframe codecs (100-150) all of those are subject to the same motion interpolation errors therefore size of I frame is the measure for image quality. My impression based on combination of codec analysys and playing the clips straight out of camera on a 10 bit panel is that the camera is not capable of resolving 10 bits anyway and that you can’t see any difference between 422 and 420 so for majority of cases 100 or 150 mbps look the same and I do not see any banding on my screen dark scenes or blue skies In terms of editing I have done not tests but you cant edit h264 decently so you need to convert to prores 422 (I use a mac) or skip h264 altogether and use all intra based on my previous experience I would always work without conversion as any operation degrades the clip. However I find it puzzling that you can’t tell the diffference between prores HQ footage acquired with an external recorder and all intra if that is really the case the only conclusion wouls be that the camera actually does not manage to resolve 10 bits at all and thereforw the spare 300 bits go to waste this theory that I cannot verify is corroborated by dxomark raw image of the GH5 that says the camera can only resolve 23.9 bits within an image which is 8 bits Using the resources as your disposal as good as you can and knowing how things work is a good thing not a bad thing so am a bit surprised that people keep going on beating up my quantitative analysis and comparing it with subjective statements quantitative and qualitative evaluations are two different things if you are happy with what you see you won’t know 8 10 bits colour spaces etc etc
  9. HDMI outputs sensor signal that is affected by debayering and aliasing but nothing to do with coding errors The GH5 outputs REC709 and REC.2020 colour spaces otherwise would not support HDR so obvously it does not just output sRGB which is synonymous of rec709 8 bits also colour spaces and bit depth are totally different things in terms of colour depth the GH5 outputs 8 bits and 10 bits colour When you record output signal from the 150 mbps modes the camera sends YCB 422 10 bit colour signal to an external recorder colour space will be rec.2020 for HLG REC709 for the rest if the camera was sending only srgb it would not record 10 bits at all In terms of saying if internal or external recording is better is then down to codecs which come after the uncompressed data clearly we need to assume panasonic is not producing faulty HDMI ports and you use decent cables now I agree that this conclusion is not something I can make so I have taken it out from the post now going back to wolfcrow point if you take the all intra out a static capture of 10 bit 422 should be 1.67 the size of 8 bit 420 but here is the opposite the 420 I frames are bigger than 422 because the 422 format spends data for motion interpolation in a less efficient manner now can you see it or not and how will the footage withstand grading is a different story most people report similar performance between all intra and 150 422 If you believe panasonic claim that cabac makes compression 20-30% more efficient and precise this would make total sense and the gap between the two smaller however not many compare 8 bit and 10 bit straight out of camera those who do say 8 bit is better and my calculations are aligned
  10. The camera does not apply any codec to HDMI out it simply passes the buffer before encoding for the recorder to acquire code and save The test you mention is not appropriate as the size of the file depends on many other things not just bitrate H264 as a bunch of flags that squeeze the file but when encoding real time most of those are not active as otherwise the processing cannot keep up. Furthermore the codec is lossy so compressing it over and over again makes it smaller Noise reduction sharpening and all that comes in the picture profiles and the rest are applied before encoding which generally only makes things worst as it can transform sharpening and noise artefacts into other errors when compressing I think the improvements that you see over the 422 10 bit are not due to the 10 bits but to 422 vs 420 sub-sampling very well explained here http://www.red.com/learn/red-101/video-chroma-subsampling
  11. No there isn’t really you have optical image translated into digital signal and then compressed at equal optical quality the compression determines the perceived quality Atomos are in the business of producing recorders but don’t own any of the codec logic I don’t know if they have a problem themselves with the hardware or software implementation for what concerns that video a guy with a black shirt on a black background with a tiny part of the frame moving doesn’t really prove much about internal vs external but it does prove the point that for simple shots the camera works just fine which is in fact the idea behind heavily compressed IPB acquisition You need a few more colours and movement to make the case although again there are many people (with a 8 bit monitor) that can take apart the 150 and 400 10 bit codec on such camera but the this could be due to the colors or detail not being there in the first place if you look on color depth measured off the GH5 it doesn’t reach 24 bits or 8 bits rgb for raw... So maybe the point is although the internal codecs will not allow for real 10 bits 422 uhd the camera doesn’t capture that detail anyway and therefore external recorders are a waste still a bigger screen than the gh5 lcd would be nice!
  12. It isn’t mor There isn’t an IPB 150 mbps 10 bit codec, the codec is IP only like Sony xavc. The level of compression is actually less than IPB 100 mbps or IPB 150 mbit 8 bits as you can see from the stream analysis there is less information packed in there the reason you can’t decode it easily is because at 10 bit uncompressed your graphic card probably overflows The all intra has no cabac entropy encoding it just has intra frame interpolation pretty much like prores. Cabac introduces 20-30% efficiency so the codec once you shoot a static scene like yours are not much apart in terms of the prores comparison the avc intra does not have any technical benefits over prores so maybe the atomos implementation has problems on its own
  13. LOG is another form of compression overlayed on all the rest. I don’t use it but I would think this is too much to take for the 100/150 IPB codecs maybe the 150 mbps IP only works better with it assuming you don’t get motion artefacts For what concerns Luma my understanding is that it is linked to RGB coefficients it does not exist in isolation so your greys come fromntbeyae source so if you cant display 10 bit red you won’t see it either for me banding etc are more due to compression. I had a sony camera and the codec was the same at avchd and xavc despite different container I would get banding with 24 mbps but not with 50 and it was still 8 bits LOG should work better with All-Intra as there is more headroom just for clarity am not saying this camera is crap what am saying is that some of the features are not fully implemented at least for in camera recording Maybe I should have put a question mark in the title...
  14. I have looked into Panasonic avc intra documentation In terms of all intra as implemented in the GH5 Cabac entropy encoding is not used only DCT is used so the assumption that this implementation of avc intra is similar to prores holds For what concerns the equivalent bit rate calculation that assumes no error of motion interpolation. This of course can be true or not depending on the situation however on a static scene the calculations hold and the considerations are valid furthermore IPB codec use cabac encoding so provided that the motion interpolation works it is likely that the quality of the image is pretty much the same in the 420 8 bit implementation (Panasonic claims 20-30% increased efficiency with cabac) It is obvious that the choice between an intra codec and long gop depends on the amount of motion in the scene and what this proves is that the 100 mbps and 400 mbps produce very similar results in certain circumstances. The post only aims at ranking the various options and to show that one of the implementations the 150 mbps 422 10 bit long gop is inferior to the others as the h264 codec is the same and the settings for that one are worst than the others prores conclusions need testing and it is possible that the camera is not good enough to push the boundaries of Prores 422 HQ anyway and therefore we see no difference from all intra Am not sure I follow fully some of those issue depend on the quality of the codec not just 8 to 10 bits 8 bit colour should not give banding anyway and the fact you can apply corrections without breaking the codec has to do with the compression headroom more than anything else?
  15. There is no need to analyse the frames for a relative comparison as the AVC family of Panasonic codec use the same algorithm only the GOP structure changes this is well explained in panasonic documentation of the codec so the assumption holds true in terma of avc intra being a proxy for prores I take the point but I have no information to conclude that the image processing of avc intra is better
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