\label{fig:compositor_window}
\end{figure}
-The Compositor window (figure~\ref{fig:compositor_window}) is used to display the timeline output. Playing and moving along the timeline video in the Program window shows in the Compositor window what the current image is. Here is where many compositing operations are performed that can change what the timeline will look like and that is why it is called \textit{canvas}. The canvas dimesions correspond, by default, to the W/H values set in the project (\textit{Set Format} window).
+The Compositor window (figure~\ref{fig:compositor_window}) is used to display the timeline output. Playing and moving along the timeline video in the Program window shows in the Compositor window what the current image is. Here is where many compositing operations are performed that can change what the timeline will look like and that is why it is called \textit{canvas}. The canvas dimesions correspond, by default, to the W/H values set in the project (\textit{Set Format} window). Canvas size = output size = project size.
When enabled, you can simply click the LMB in the Compositor window to start and stop play. You can zoom in and out to see small details, pan with the scrollbars, lock the window to prevent changes, add masks, and make changes with the Projector and Camera function operators. These will be explained in more detail in the following sections.
Much of the editing in \CGG{} involves \textit{compositing} which is the combining of visual
elements from different sources into single images. This includes such things as
speeding up and slowing down the video, changing the resolution, creating a split screen, and fading in and out.
-Compositing operations are done on the timeline and in the Compositor window using various
+Compositing operations are done on the timeline and in the Compositor window (canvas) using various
operations and other compositing attributes that are available in the Resources window.
When \CGG{} is performing a compositing operation it plays back through the
compositing engine, but when not, it uses the fastest decoder that it has.
\label{ssub:output_size}
\index{temporary}
-\CGG{}'s compositing routines use a \textit{temporary} which is a single frame of video in memory where graphics processing takes place. By default the size of the temporary is that of the project ($W \times H$), i.e., the output size. But if the tracks on the timeline have various sizes different from those of the project, then the temporary will take the size of the active track (viewport = green border). We can also change the size of the viewport using the Camera tool, as well as pans and zooms the temporary displayed in it. Effects are processed in the temporary and as such are affected by the temporary size. In the case of the camera, its viewport is the temporary size. The size of the temporary and of the output in the compositing pipeline can be different and vary for any particular frame. However, projectors are rendered to the output and so are affected by the output size. The temporary is the basis on which the Projector tool acts to display the canvas on the Compositor window. The canvas always has the size of the project, although with the projector we can make pans and resizes of the red border inside it. When the temporary is smaller than the output, the temporary will have blank borders around the region in the output. When the temporary is larger than the output, it will be cropped.
+\CGG{}'s compositing routines use a \textit{temporary} which is a single frame of video in memory where graphics processing takes place. By default the size of the temporary is that of the project ($W \times H$); i.e., the output size; i.e, the canvas size. But if the tracks on the timeline have various sizes different from those of the project, then the temporary will take the size of the active track (viewport = green border). We can also change the size of the viewport using the Camera tool, as well as pans and zooms the temporary displayed in it. Effects are processed in the temporary and as such are affected by the temporary size. In the case of the camera, its viewport is the temporary size. The size of the temporary and of the output in the compositing pipeline can be different and vary for any particular frame. However, projectors are rendered to the output and so are affected by the output size. The temporary is the basis on which the Projector tool acts to display the canvas on the Compositor window. The canvas always has the size of the project, although with the projector we can make pans and resizes of the red border inside it. When the temporary is smaller than the output, the temporary will have blank borders around the region in the output. When the temporary is larger than the output, it will be cropped.
\subsubsection*{Track and Output size}%
\label{ssub:track_size}
The aspect ratio is the ratio of the sides of the frame (\textit{Width} and \textit{Height}). For example, classically broadcast TV was 4:3 (= 1.33), whereas today it has changed to 16:9 (= 1.78); in cinema we use the 35 mm aspect ratio of 1.375 (Academy aperture), academy flat (1.85 or widescreen) but even more so the super 35 mm (from 1.33 to 2.39). There are also anamorphic formats, i.e. that have no square pixels, like Cinemascope (2.39). The projection must be normalized to have an undistorted view.
-
From the film or digital sensors of the cameras, we can extract any frame size we want. We are talking about \textit{viewports}, which we will examine shortly. Also important is the output of the video that will be rendered, because it is what we will see at the cinema, or on TV, or on the monitor of the PC, tablet or smartphone. Referring to figure~\ref{fig:temporary-01}, you can see these two possibilities: with the \textit{Camera} tool you choose the size and aspect ratio of the source file (regardless of the original size); while with the \textit{Projector} tool you choose the size and aspect ratio of the output. Other ways of changing the aspect ratio of assets or tracks we have seen previously (\texttt{Resize track}; \texttt{Match Output Size}; \texttt{Resize asset}). A method of changing the size of the entire project (canvas) is via the \texttt{Set Format} window. The following formula is used to vary the aspect ratio:
\qquad $\frac{W}{H} =$ frame aspect ratio ($\frac{pixels}{pixels}$)
At the same time as changing the \textit{Height} parameter we also need to set \texttt{Display Aspect rati}o to 2.35. In fact, the parameters in Canvas Size are not related to those in Display Aspect ratio, unless we keep the \texttt{Auto} option checked, and we need to set both before we click on the \texttt{Apply} button. To set the aspect ratio to 2.35:1 we can choose from the drop-down menu the value 2.35 or set the value directly in the two input fields. Or again, it can be done automatically via the Auto option. Finally we can click on the Apply button to complete the calculations. Now we have arrived at the desired result: typical Super 35 mm dimensions and aspect ratio, although starting from a 16:9 FullHD. The new canvas, however, lost the pixels of a part of the initial video (crop), to be precise $1080 - 816 = 264$ lines of pixels from top and bottom.
-\CGG{} allows you to vary the input and output aspect ratio in the ways indicated in the previous section: by varying the pixels of the sides (Width/Height) or by setting a multiplication coefficient (W/H Ratio; in this example: placing $H Ratio = 816 : 1080 = 0.7556$) which performs the calculation automatically. If you set \textit{W Ratio} and \textit{H Ratio} at the same time with the same values, they work as multipliers and you get a resizing of the canvas, without altering the initial aspect ratio. If you change them to two different values or change only one of the two parameters, leaving the other at 1, you get an anamorphic video, with the pixels no longer being square (1:1) but becoming rectangular, deforming the image. To avoid anamorphosis, the \texttt{Display Aspect ratio} must also be adjusted at the same time, for example, with the Auto option. \textit{Anamorphic} format is a complex field that is discussed
+\CGG{} allows you to vary the input and output aspect ratio in the ways indicated in the previous section: by varying the pixels of the sides (Width/Height) or by setting a multiplication coefficient (W/H Ratio; in this example: placing $H Ratio = 816 : 1080 = 0.7556$) which performs the calculation automatically. If you set \textit{W Ratio} and \textit{H Ratio} at the same time with the same values, they work as multipliers and you get a resizing of the canvas, without altering the initial aspect ratio. If you change them to two different values or change only one of the two parameters, leaving the other at 1, you get an anamorphic video, with the pixels no longer being square (1:1) but becoming rectangular, deforming the image. If you use a non-standard aspect ratio, this has impact on other areas like titles, included stills and included non-anamorphotic footage. To avoid anamorphosis, the \texttt{Display Aspect ratio} must also be adjusted at the same time, for example, with the Auto option. \textit{Anamorphic} format is a complex field that is discussed
in Andrea's paper: {\small \url{https://cinelerra-gg.org/download/Anamorphic.pdf}}.
as well as in the Raffaella Traniello's guide: {\small \url{http://www.g-raffa.eu/Cinelerra/HOWTO/anamorphic.html}}.
-
\subsection{Camera and Projector}%
\label{sub:camera_and_projector}
\index{camera}
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