Some cameras are not good at compensating differences in brightness. Then you want to brighten or darken your video a ittle bit. You can do that with ffmpeg.
UNIX Shell Script
The basic command is
ffmpeg -v error -y -i $sourceVideo -vf eq=brightness=0.2 -c:a copy $targetVideo
but we need to care also for the time_base of the created video,
else it may not be combineable with other videos of the same serie.
Here is a script that accepts a video XXX.mp4 on command line and ceates a video XXX_brighter.mp4 from it, being in the same folder as the original video. If 0.2 (20%) brighter is not sufficient for you, you can increase that by setting your chosen value as second command line argument.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 | brighter=0.2 # 20% brighter sourceVideo=$1 [ -z "$sourceVideo" ] && { echo "SYNTAX: $0 videofile [brightnessIncrement]" >&2 echo " Brighten or darken a video, default brightnessIncrement is 0.2 for 20% brighter, use -0.1 for 10% darker" >&2 echo " If videofile is xxx.mp4, the result file will be xxx_brighter.mp4." >&2 exit 1 } [ -f "$sourceVideo" ] || { echo "Not a file: $sourceVideo" >&2 exit 2 } [ -n "$2" ] && { brighter=$2 } sourceDir=`dirname \$sourceVideo` sourceFile=`basename \$sourceVideo` filename=${sourceFile%.*} # filename without extension extension=${sourceFile#*.} # extension without filename targetVideo=$sourceDir/${filename}_brighter.$extension # keep time_base getInverseTimeBase() { # $1 = video file path ffprobe -v error -select_streams v:0 -show_entries stream=time_base -of default=noprint_wrappers=1 $1 | sed 's/time_base=1\///' } inverseTimeBase=`getInverseTimeBase \$sourceVideo` keepTimeBase="-vsync 0 -enc_time_base -1 -video_track_timescale $inverseTimeBase" echo "Changing brightness of $sourceVideo to $brighter ...." >&2 ffmpeg -v error -y -i $sourceVideo -vf eq=brightness=$brighter -c:a copy $keepTimeBase $targetVideo || exit 3 echo "Created $targetVideo" |
- Lines 1 sets the brightness increment default
- Line 2 defines the source video as first command line argument
- Line 4 checks that the argument is not empty and outputs help if so
- Line 10 checks if that is a real file
- Line 15 and 16 set the brightness increment optionally from second command line argument
- Lines 19 to 23 create the target file name for the brighter video
- Lines 25 to 30 calculate the
time_baseto use from the original video - Line 34 finally is the ffmpeg command, this takes a while to change any frame of the video.
Hope this was helpful!
