Utility Scripts for ffmpeg

Part of my new ffmpeg toolbox are some utility scripts that I want to present in this article.

All scripts would output their syntax and exit when called without command line arguments.

Display Video Properties

videoProperties.sh

#######################################################
# Displays quality settings of video and audio.
#######################################################

[ -z "$1" ] &&    {
    echo "SYNTAX: $0 [-a|videoPropertyCsv] videoFile [videoFile ...]" >&2
    echo "Shows significant properties of first video and audio stream." >&2
    echo "-a: show full property listing" >&2
    echo "videoPropertyCsv: comma-separated list of video properties to show" >&2
    exit 1
}

formatProperties()    {
    ffprobe -v error \
            -show_entries format=$1 \
            -of default=noprint_wrappers=1 $2 \
        | sort \
        | uniq \
        | sed 's/^/format /'
}

streamProperties()    {
    ffprobe -v error \
            -select_streams $2 -show_entries stream=$1 \
            -of default=noprint_wrappers=1 $3 \
        | sort \
        | uniq \
        | sed 's/^/'$2' /'
}

for argument in $*
do
    if [ -f "$argument" ]
    then
        videoFile=$argument
        echo "Properties for $videoFile" >&2
        
        if [ -n "$propertyList" ]
        then
            streamProperties $propertyList v:0 $videoFile
        elif [ "$showAll" = "true" ]
        then
            ffprobe -v error -show_format -show_streams $videoFile
        else
            formatProperties format_name,bit_rate $videoFile
            streamProperties codec_name,profile,time_base,pix_fmt,r_frame_rate,width,height,bit_rate v:0 $videoFile
            streamProperties codec_name,sample_rate,channels,bit_rate a:0 $videoFile
        fi
    elif [ "$argument" = "-a" ]
    then
        showAll=true
    else
        propertyList=$argument
    fi
done

For every given video file, it would output the most important quality properties, prepending "format" for general, "v:0" for video and "a:0" for audio, so that we can see where the property belongs to. If you give one or more property names (comma-separated without spaces), it would restrict the output to video-stream properties of that name (just the first video of possibly several).

The option -a ("all") would cause a full output of all stream- and format- properties. Mind that there could be also programs and subtitles inside the video.

Extract Image at Time

extractImage.sh

#######################################################
# Extracts an image from given video at given time.
#######################################################

IMAGEFILENAME=image.png

[ -z "$1" -o ! -f "$1" -o -z "$2" ] &&    {
    echo "SYNTAX: $0 videoFile time [imageFilePath]" >&2
    echo "Extracts an image from a video to default image file $IMAGEFILENAME" >&2
    echo "Example:" >&2
    echo "    $0 myvideo.mp4 1:23 title-image.png" >&2
    echo "    would extract the key-frame image at or before minute 1 second 23" >&2
    echo "    from myvideo.mp4 to title-image.png." >&2
    exit 1
}

video=$1
time=$2
image=${3:-$IMAGEFILENAME}

ffmpeg -y \
    -ss $time -i $video -frames:v 1 \
    -f image2 $image

First argument is the video file, second the time when the targeted image occurs, optional third the name of the resulting image file.

The ffmpeg command uses input-seeking (-ss before -i), thus it would find a key-frame at, or shortly before, given time. Mind that you can also specify thousands seconds by adding ".111" to seconds.

Calculate Duration of Videos in a Folder

durationOfVideos.sh

#######################################################
# The rounded duration of all videos in given directory.
#######################################################

[ -z "$1" ] && {
    echo "SYNTAX: $0 videoDir" >&2
    exit 1
}

cd $1 || exit 2

sum=0
for video in `ls -1 *.MP4 *.mp4 2>/dev/null | sort`
do
    seconds=`ffprobe -v error -show_entries format=duration -of default=noprint_wrappers=1:nokey=1 \$video`
    sum=`echo "\$sum \$seconds" | awk '{ print $1 + $2 }'`
    
    echo "$video: $seconds seconds" >&2
done

echo "sum of seconds = $sum" >&2

rounded=`echo \$sum | awk '{ print int($1 + 0.5) }'`
    
hours=`expr \$rounded / 3600`
rest=`expr \$rounded % 3600`
minutes=`expr \$rest / 60`
seconds=`expr \$rest % 60`

echo "$hours:$minutes:$seconds"

This script specializes on MP4 files. If you have others, replace the ls -1 wildcard patterns in line 13.

It changes to the given video directory, loops all videos and displays their duration in seconds on stderr. Finally it displays the rounded sum in hours:minutes:seconds format on stdout.

Because bc ("binary calculator") is not installed on every UNIX system, I use awk for calculations. It processes decimal numbers precisely, while the expr ("expression") command can process only integers.

Output Key-Frame Seconds

keyFrameSeconds.sh

###########################################
# Outputs the seconds when key-frames occur.
###########################################

[ -f "$1" ] || {
    echo "SYNTAX: $0 videoFile" >&2
    echo "Outputs the times when key-frames occur in given video." >&2
    exit 1
}

ffprobe -v error \
    -select_streams v:0 \
    -skip_frame nokey \
    -show_frames -show_entries frame=pkt_pts_time \
    -of default=noprint_wrappers=1:nokey=1 \
    $1

This script my be useful when you want to know where the key-frames are in your video.