Proxies were 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 (for example h264/5) are very compressed and interframe type, so they are more CPU intensive for timeline playback. These files cause performance problems on smaller computers. As a solution, proxies were introduced to reduce the file size. Reduced means to minimize the resolution/dimension, as usually not the full resolution is needed because the compositor generally occupies only a fraction of the computer screen. The proxy provides a scaling factor which indicates how much the original resolution should be reduced. There is also the proxy 1:1 option that maintains the original resolution but still allows you to modify codec parameters (lowering the bit rate, for example). This is explained in the next section, 6.2. Always remember when getting ready to render the project, disable Proxy to return to the original settings with the highest quality.

To use proxy select Settings Proxy settings on the main window. You can choose ffmpeg as the File Format and for the File Type a choice of various codecs associated with that. A good choice for File Type is the default of mpeg or mov which can usually be quite fast. In addition you can modify values for that codec by clicking on the wrench icon. Once you have created a proxy file, it will be reused and does not have to be created again as long as you do not change certain parameters. This saves a lot of CPU time.

There are two main ways to use Proxy, with or without Rescaled to project size option checked. The options of the Scale factor may be different if Rescaled to project size is checked versus unchecked. It is a special case when the Scale factor is set to "1" and it does not matter if Rescaled to project size is checked or unchecked.

The usual steps to use Proxy are:

  1. Check that File Format is set to FFMPEG.
  2. Check or uncheck the Rescaled to project size (FFMPEG only). The difference with this option will be explained here 6.1.1. But for old computers checking Rescaled to project size is not recommended; again due to requiring more CPU. You need to know that when Rescaled to project size is unchecked some Effects/Plugins do not work as expected because they use pixel values instead of percentage values as is used in the Project Format. For example Title, Blur, Sketcher plugins do not work right if unchecked, while Perspective and Crop&Position plugins work correctly for both checked and unchecked.
  3. Choose the Scale factor. The options may be different if Rescaled to project size is checked or unchecked. The smaller the Scale factor is, the smoother playing on the Timeline will be ( ${\frac{{1}}{{8}}}$ is smaller than ${\frac{{1}}{{4}}}$), but on the Viewer/Compositor the image will be degraded/pixelated more.
  4. Set the File Type in the File Format for FFMPEG, such as mp4, mpeg, or mov. Still images like jpg, tiff, and png will be converted to PNG files with alpha channel if it had an alpha channel.
  5. Click on the wrench icon to configure video compression; just use the default values if you are unsure and prefer not to experiment.
    1. Select the Compressor type (codec).
    2. Change Bitrate, or Quality, and Pixels. Because not all codecs use the alpha channel for transparency, check that the letter "a" is in the Pixels name (such as yuva420p or rgba) to retain the alpha channel.
    3. Click on the OK button to close the Compressor window.
  6. Now click on the OK button to start the rendering for the proxy.
  7. Look in the lower right corner of the main window where there is a progress bar and a percentage value showing the progress of the creation of proxies, and in the lower left corner there is the Creating proxy files... ETA: hh:mm:ss text with the "Estimated Time of Arrival (completion)" in hours, minutes, seconds. Depending on how many files your project uses, the file size, which codec is used, the scale factor, and cpu performance, creating proxies may take some time.

You will know that Proxy mode is enabled because:

The Proxy icon is a toggle button so that you just click on the icon to change modes. Or it can be toggled using the Ctrl+R shortcut.

Table 6.1: list States of the Proxy icon
Proxy State Rescaled to project size (FFMPEG only) Proxy icon for themes: Cakewalk/ Neophyte Proxy icon for themes: the Others
Off checked/ unchecked no icon no icon
Active (Enable) checked Ps: P(green) s(white) S (white)
Disable checked Ps: P(red) s(white) S (gray)
Active (Enable) unchecked Ps: P(green) s(red) P (white)
Disable unchecked Ps: P(red) s(red) P (gray)

When you disable Proxy using the toggle button for Proxy, or its shortcut (Ctrl+R), in the Proxy Settings window you will see the Scale Factor = 1, but if you look at the Active Scale and the State, you can understand what your setting is. Proxy can have three possible States: Off, Active, Disabled. The difference between Off and Disabled is that Disabled means you have set the Proxy and it is temporarily switched off (and you can see the icon in the upper right corner of the main window); you can enable proxy by just clicking on the icon, so the State will then be changed from Disabled to Active.

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