README.md

Archiving operations

Merging/concatenating multiple videos in a directory into a single video

1. Place concatenate_within_folder.bat at the top of the directory tree
2. Open command line at location where the batch file is placed
3. Run the batch file by typing concatenate_within_folder.bat in the command line
4. See instructions within batch file for more details

Replicating directory with compressed videos

1. Place move_compress.bat at the top of the directory tree
2. Open command line at location where the batch file is placed
3. Run the batch file by typing move_compress.bat in the command line
4. See instructions within batch file for more details

Line-by-line explanation

concatenate_within_folder.bat

@echo off & setlocal
set "compress_factor=4";
FOR /r %%i in (.)  DO (	    
    cd "%%~fni" 
    del "list_to_concat.txt"           
    for %%f in (*.avi) do (
        echo file %%f >>  "list_to_concat.txt"             
    )
    ffmpeg -f concat -safe 0 -i "list_to_concat.txt" -c copy -vcodec libxvid -q:v %compress_factor% -an -y "%%~fni/%%~ni_concat.avi"    
    echo "done"
)

1. @echo off & setlocal

• Display options \
  • @echo off Turns off the command being displayed in the command line \
  • setlocal command is used so that variables defined (see next section) are local in scope. For more explanation, see Local v/s Global variables

2. set "compress_factor=4"; Here we define and assign a local variable called compress_factor.

3. FOR /r %%i in (.) DO ( ... )

• This is a for loop in batch scripting
  • /r option is used to iterate through all folders and subfolders
  • %%i is the loop variable -- here it is a placeholder for a directory
  • in (.) -- specifies to begin searching for all directories iteratively, starting from the directory where batch file is placed
  • DO (...) -- carry out the commands within the parentheses

4. cd "%%~fni"

• Change directory to the directory that is being looped over
  • cd -- change directory
  • %%~fni is the path to the directory i (which is the loop variable)
  • %% is usually placed before a loop variable (here i, which is the directory name) to invoke the value of the variable
  • ~ -- indicates that it is a path
  • fni -- folder name of ith folder
  • `~fni

5. del "list_to_concat.txt"

• Searches the current directory for the file "list_to_concat.txt" and deletes it (this is necessary as we need to create a new text file with the list of videos to be merged

6.  for %%f in (*.avi) do (
        echo file %%f >>  "list_to_concat.txt"             
    )
   

• This is a for loop that finds all AVI files in the current directory and adds the line file NAME_OF_AVI to the text file list_to_concat.txt
  • The syntax of for loop is similar to what is explained above;
  • %%f is the loop variable
  • (*.avi) is used to loop over all files with extension .avi
  • echo is used to print (this is similar to fprintf in C language).

7. ffmpeg ...

• This is the main video processing command
  • ffmpeg -- call ffmpeg
  • -f -- apply a filter (sometimes -filter_complex is also used -- see other batch files)
  • concat -- name of the filter (can use multiple filters like scale, textbox -- see other batch files in the repository)
  • -safe 0 -- Not sure what exactly, but likely a fix for unsafe filenames (see comment in this answer)
  • -i "list_to_concat.txt" -- -i stands for input; here instead of listing each input video to be concatenated, we specify a text file with list of input videos
  • -c copy -- Copy the frames directly without going through decode->filter->encode process (see answer here)
  • -vcodec libxvid -- specify the video codec (XVid here). To list all video codecs available, type ffmpeg -codecs in command line. More info here
  • -q:v %compress_factor% -- Quality of video compression. To use the value of the compress_factor (or any) static variable defined earlier, enclose them in %
  • -an -- No audio stream in output
  • -y -- Overwrites any existing output file with same name.
  • "%%~fni/%%~ni_concat.avi" -- %%~fni is the path of the current directory. %%~ni is the name of the current directory. So if you are in a directory called D:/videos, you will see an output video D:/videos/videos_concat.avi