11/27/2023 0 Comments Editready transcode gh5 footage darker![]() Video uses chroma sub-sampling so only part of the frame contain colours at a given time. If you consider a Jpeg image of your 3840×2160 frame on the GH5 you see that it stores around 4.8 MB per image because there is no chroma sub-sampling so if you wanted to have exactly the same result you would need to use ProRes 4444 to get a comparable quality (this not even taking into account that Jpeg are 8 bits images). However based on my experience this is not entirely through and you need a decent GPU to play it back and edit real time without issues. The idea of All intra is that you don’t require powerful hardware to edit without conversion in an intermediate codec. The implementation of All-Intra of the GH5 does not make use of CABAC entropy but only CAVLC coding is used, this makes the resulting files easier to read and to edit. This codec records at 400 Mbps so with 30 fps this means circa 13.4 Mbits per frame or 1.67 MB per frame and there is no motion interpolation so each frame is independent from the others. In order to understand the workings we need to dig deeper into the structure of the GOP but before doing so let’s evaluate the All-Intra codec. This is the reason why comparing All Intra and Long Gop using static scenes or scenes with repetitive movement that can be predicted very accurately by the codec is a fundamental error. The reason why H264/HEVC is very efficient is that within a group of picture there is only one full frame and the rest are predictions clearly if the prediction algorithm is accurate the level of perceived quality of long GOP is very high and similar to All-Intra clips. It is important to note that frames are not stored sequentially in a GOP and therefore the GOP needs to be decoded and the frames reordered to be played, this requires processing power. B (bi-predictive coded) frames containing a prediction from previous or future frames.P (Predictive coded) frames containing motion interpolated picture based on a prediction from previous frames.I (Intra coded) frames containing a full picture.Within a Group of Pictures there are different type of frames: ![]() The difference between Long GOP and All Intra is that in the Long GOP what is encoded is a group of pictures (GOP) and not separate individual pictures. The first option is only available on the S series and the GH5M2. The last option is only available on the GH5 series and on the S1H. ![]() For simplicity I will refer to 30 and 60 fps and not exact values. This presents some challenges if you are in a PAL zone and are shooting under artificial lights however for the purpose of this article I want to just ignore this issue, obviously you could shoot 24 fps and hope in a 24 – 30 conversion which is scatty of course. This is simply because today majority of content produced by Panasonic consumer digital cameras is consumed online and all computer screen work at 60 Hz refresh rate so shooting anything different than 30 or 60 will result in choppy video. This time I will be looking at the NTSC standard of 29.97 and 59.94 frames per second. ![]() As Before I will focus my analysis on 4K video and ignore other formats. With the S series software stack Panasonic has made some changes to the options available and I thought it was about time to refresh the original article. ![]() In 2018 I wrote the original article as I had acquired the GH5 and I was faced with a ton of non-sense on which format to use when I was shooting video. ![]()
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