# How to make TimeLapse videos

Simple instructions to make a TimeLapse **using HomeScope's Raspberry Pi Linux Shell**.

## Step 1: 

First **make a directory** using the Linux bash shell command `mkdir` (here called `My_Timelapse`). 

> `mkdir My_Timelapse`

Get into the directory you just created using the `cd` command.
Do all other steps (commands) in this directory--not anywhere else.

> `cd My_Timelapse`


## Step 2:

**Take several microscopy pictures** with the same time interval between them (`DELTA_T`) 
for a total lengh of time (`TOTAL_T`).

Use the `libcamera-still` command, and put in the parameters for the total amount of time (`-t TOTAL_T`, in milliseconds)
and the frequency (`--timelapse DELTA_T` in millisecods) you want to be taking pictures.

Be **carefull** to do not fill the drive (SD card) with too many pictures as it will crash the system.
Make sure the table with your HomeScope is not disturbed with vibrations.

For **example** , 
for taking pictures *every 10 minutes* (`DELTA_T = 600000` milliseconds) *for a 2 hour period* (`TOTAL_T = 7200000` ms).
We use the pattern `PictureN.jpg` to name pictures as numbered (`N`) jpg files (`N={0000,...0013}`). 
The numbers are added to the filename by the structure `%04d` specifying 4 digit number pattern

> `libcamera-still -t 7200000 --timelapse 600000 --framestart 1 -o Picture%04d.jpg`
 


## Step 3:


Make a text file called `photos.txt` by using the Linux bash shell command `ls` to list all the pictures files 
in the directory using the command. To save the list (output of the command) to a file called `photos.txt`, 
redirect the output of the command from the standard oputput (the screen) to the filesystem with the command line:  


> `ls *.jpg > photos.txt`



## Step 4:


Build the final movie stiching all frames together with the command `mencoder` (maplayer) as follows


> `mencoder "mf://@photos.txt" -mf fps=1 -o timelapse_video.avi -ovc lavc -lavcopts vcodec=mjpeg:vbitrate=1600 vqmin=3`



## Step 5:

**Play the movie** To play the `avi` file use the `mplayer` command:


> `mplayer timelapse_video.avi -fs`