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interceptor121

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  1. As I started this mess I wanted to give an update some time later AVC-I at 400 Mbps beats the xxxx out of ProRes 422 and I could not see any difference to ProRes 422 HQ at naked eye and pixel peep Looking for explanations I believe is due to two things 1. intraframe predictive coding on 16x16 blocks that achieves high level of compression than standard discrete cosine transform in ProRes 2. CABAC entropy encoding squeezing additional bits without loss in the clips It is difficult to average what the benefits are compared to ProRes but is not difficult to see tha
  2. 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
  3. 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 is
  4. 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 no
  5. 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 co
  6. This table is useless as even if the codec is the same the compression settings differ that was the whole reason for my post
  7. 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
  8. 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 co
  9. 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
  10. 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
  11. 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 w
  12. 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 wo
  13. 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
  14. 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
  15. 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
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