the original media, you can alleviate the lag between the Audio and Video by disabling
\textit{Play every frame} in \texttt{Settings $\rightarrow$ Preferences, Playback A} tab. Now frames
will be skipped in order to keep the audio/video in synch.
+
+\subsection{How to remove letterbox/pillarbox bands}%
+\label{sub:remove_letterbox}
+
+To remove the horizontal black bands of the letterbox or the vertical
+black bands of the pillarbox we need to change the \textit{size} and
+\textit{aspect ratio} of the source by cropping.
+For example, if we want to remove the letterbox from a $4:3$ frame to
+leave only the content with aspect ratio $3:2$, We have to change the
+project format by doing the following steps:
+
+\begin{enumerate}
+ \item Check the size of the base W of the original frame in pixels:
+
+ \texttt{Resource} window $\rightarrow$ \texttt{RMB} on Asset
+$\rightarrow$ \texttt{Info} $\rightarrow$ \texttt{Detail}; e.g. W =
+768 px
+ \item Obtain the height of the figure in $3:2$, i.e., without the
+black bands; H can be obtained from the formula:
+
+ $\frac{3}{2} = \frac{W}{H}$ \quad from which $H = \frac{768 \times
+2}{3}$ \qquad e.g., H = 512 px
+ \item Note that $W \times H = 768 \times 512$ is just the crop we
+are looking for to switch from $4:3$ frame to $3:2$ frame without
+letterbox.
+ \item Open \textit{Set Format} window: \texttt{Settings
+$\rightarrow$ Format}
+ \item Change $H = 512$ and set \textit{Display Aspect Ratio} to
+$3:2$; press \texttt{Apply} and \texttt{OK}. Note that we leave W
+unchanged, since the frame width does not change.
+ \item If needed, use the \textit{Camera} tool to get the
+desired viewport.
+\end{enumerate}
+
+\paragraph{Note:} in complex situations, with multiple sources of
+different sizes, it may be appropriate to perform an additional
+step first: change the size of the track on the Timeline via
+\texttt{RMB $\rightarrow$ Resize track}.
+In this way we crop the track to match it to the project format that
+we will change in the next step. Thus we avoid possible unwanted
+distortions.
+
+In the case of the pillarbox, we will leave H unchanged while
+calculating the new value of W. The formula $\frac{x}{y} =
+\frac{W}{H}$ is valid for any aspect ratio ($4:3; 16:9; 2.35:1$; etc).
+