{"id":95416,"date":"2017-10-09T06:00:20","date_gmt":"2017-10-09T11:00:20","guid":{"rendered":"https:\/\/www.premiumbeat.com\/blog\/?p=95416"},"modified":"2017-10-09T09:53:58","modified_gmt":"2017-10-09T14:53:58","slug":"gh5-long-gop-intra-compression","status":"publish","type":"post","link":"https:\/\/www.premiumbeat.com\/blog\/gh5-long-gop-intra-compression\/","title":{"rendered":"GH5’s Latest Update: Long GOP vs. ALL-Intra Compression"},"content":{"rendered":"

The latest firmware update for the GH5 is finally available. Here’s what you need to know about compression.<\/h2>\n

Cover image via Shutterstock<\/a>.<\/em><\/p>\n

The highly anticipated V2.0 firmware for the Panasonic GH5 is finally became available<\/a>. One of the newest features is the ability to record with an ALL-Intra compression<\/strong>, rather than using Long GOP. With\u00a0all the excitement over this new addition to the GH5, many casual GH5 owners are flocking to the forums to find out what the fuss is about and if it is worth purchasing larger memory cards<\/strong> to\u00a0film with the new compression format.<\/p>\n

First, we have to understand a little bit about codecs (CO<\/b>mpression-DEC<\/b>ompression). By nature, the very subject can be tedious to learn about, so we’re only going to focus on the areas surrounding the GH5.<\/p>\n

Typically codecs fall into two categories: compressed and uncompressed<\/strong>.<\/p>\n

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\"GH5's
\n<\/a>Image via Panasonic.<\/em><\/p>\n

Compressed codecs<\/strong> reduce the size of the media by disregarding information that is not essential<\/strong> for viewing. This is not to say that compressed video footage will look awful. I think there’s a misconception that compressed footage is bad<\/strong>. Perhaps 99-100 percent of what the general population views each day is compressed: YouTube videos, BluRays, the news, and so on.<\/p>\n

However, on a technical aspect, it’s important to know that the data information<\/strong> in some of the frames is not complete. Every frame in a clip is not a full frame. If that’s the case, what are we seeing?<\/p>\n

The DaVinci Resolve 12.5 Editing 101 guide<\/strong> has perhaps the clearest explanation of how GOP compression works.<\/p>\n

The first frame of a GOP structure is an I-Frame (or intraframe), and it contains all the information for that one particular frame, practically uncompressed. The next frame is called b-frame (or bidirectional) which only stores the changes or differences between the I frame and the B frame. Typically, there is then a second B frame followed by a P-frame (or predictive frame) which merely predicts what the structure will look like based on the information of the previous b-frames.<\/p><\/blockquote>\n

\"GH5's<\/p>\n

Above is a rendition of the Long GOP compression from Wex Photographic<\/a>. The compression will often have a lot more P and B frames between the I-frame<\/strong>.<\/p>\n

So, in layman’s terms, GOP compression only displays the changes between both I-frames<\/strong>. If pixel 3,465 is the same at I-Frame 1 as it is in I-frame 2, there will be no change throughout the bi-directional or predictive frames<\/strong>. While this appears fine for most, fundamentally it\u2019s not the true frame information as found in the I-Frame (sometimes referred to as the keyframe). The further compressed a video file is, the further apart the I-frames, and the less “real” frames there are to interpret. This is when we start\u00a0seeing video footage filled with artifacts and missing data. This is due to heavy compression<\/strong>.<\/p>\n

In the video below,\u00a0Kristian Hampton of Wex Photographic<\/a>\u00a0explains the difference between the two compression formats<\/strong> and offers some visual examples.<\/p>\n