Side By Side Video Makefile

 

Creating a side-by-side video from two input files requires knowledge of the input file dimensions, mainly to extend the overlay to a proper size and applying the overlay.  Most often, this is manually specified in the command line, but with some constraints some of it can be automated in a makefile.

If the left-most video dimensions are larger than the right, the following makefile will place the videos side-by-side and pull the audio from the left-most file.

$ cat Makefile 

all: sideBySide.mp4

left.mp4: ../big_buck_bunny_1080p_h264.mov

${SH} ffmpeg -i $<  -filter:v "crop=1024:768:0:0" -ss 60 -t 10 $@

right.mp4: ../big_buck_bunny_1080p_h264.mov

${SH} ffmpeg -i $<  -filter:v "crop=1280:720:0:0" -t 15 $@

%.size: %

${SH} ffprobe -v error -show_entries stream=width,height $< > $@

#--generate side-by-side, assumes left image is larger (or equally large) to right image

sideBySide.mp4: left.mp4 right.mp4 left.mp4.info right.mp4.info

${SH} export left=$(shell echo $^ | cut -d ' ' -f 1); \

      export right=$(shell echo $^ | cut -d ' ' -f 2); \

      export W1=$(shell grep "^width=" left.mp4.info | cut -f 2 -d '='); \

      export H1=$(shell grep "^height=" left.mp4.info | cut -f 2 -d '='); \

      export W2=$(shell grep "^width=" right.mp4.info | cut -f 2 -d '='); \

      export H2=$(shell grep "^height=" right.mp4.info | cut -f 2 -d '='); \

      export Y=$(shell echo '\($$H1-$$H2\)/2'); \

      ffmpeg -i $$left -i $$right -filter_complex "[0:v]pad=$$W1+$$W2:0:color=gray[int];\

                     [int][1:v]overlay=$$W1:0+$$Y[vid]" -map "[vid]" -map 0:a -acodec copy $@

%.info: %

${SH} ffprobe -v error -show_format -show_streams $< > $@

clean:

${RM} *.mp4 *.info

For more details, refer to FFmpeg Official Site: http://ffmpeg.org/