-Working with videos that have large image geometry can greatly impede editing. Instead you can substitute \textit{proxies} which will create smaller video image files from the original file that can then be edited more quickly. When you are done working on this smaller scale, you will need to bring up the Proxy settings menu again, and change the Scale factor back to the Original size so that all of your edits/work take affect on that original higher quality video on the timeline.
+Proxies was introduced to allow for a smoother timeline experience. Full HD and everything from 4K size up are usually very large in file size. In addition, some commonly used codecs (e.g. h264/5) are very compressed and interframe type, so they are more stressful for timeline playback. These files cause performance problems on weaker PCs. As a solution the developers have introduced proxies to reduce the file size. Reduced means to minimize the resolution/dimension, as usually not the full resolution is needed, because the compositor usually takes only a fraction of the computer screen. Therefore the scaling factor, which indicates how much the original resolution should be reduced.
+There is also the \textit{proxy 1:1} that maintains the original resolution but still allows you to act on the codec (lowering the bit rate, for example). See also next section: \ref{sec:transcode}.
+When rendering, the original setting will be used to avoid loss of image quality.
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+To use the proxy in a classic way, i.e. as a scaling, select \texttt{Settings $\rightarrow$ Proxy settings} and change the Scale factor from Original size to your downsized choice. You can choose ffmpeg as the File Format and a choice of various codecs associated with that. A good choice is the default of mpeg which can usually be quite fast. In addition, to modify values for that codec, click on the wrench icon.
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+We can use the \textit{Proxy 1:1} in two ways: setting "1" as \textit{Scale factor}, or check the \textit{Rescaled to project size (FFMPEG only)} button. In this mode we don't have scaling, i.e. downsize, but only variations of the codec parameters that allow to maintain the original resolution. The advantage is that you can use filters that require the original size to work well. NB: if we set any scaling, by activating the \textit{Rescaled to project size (FFMPEG only)} button we automatically lose scaling and enter Proxy 1:1 mode.
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+When you have completed your choices, just click OK, and then the video tracks will be rendered. This may take some time, but previous proxy renders will be reused.