modules/mp4_to_png.sh

#!/bin/bash
# Options
PLAYLIST_URL=https://youtube.com/playlist?list=PLwlIgd6_8FLJqgvIgtUye8Jz2jSKLrCAI
IMAGE_NUM=20
# ----- Start script -----
# get playlist name
PLAYLIST_NAME=$(yt-dlp --no-warnings --dump-single-json --playlist-end 1 $PLAYLIST_URL | jq -r '.title')
echo "Playlist Name:" $PLAYLIST_NAME
# get CPU threads
CPU_THREADS=$(grep processor /proc/cpuinfo | wc -l)
RUN_THREADS=$(($CPU_THREADS/2))
echo "cpu threads:$CPU_THREADS"
echo "run threads:$RUN_THREADS"
# get script dir
SCRIPT_DIR=$(cd $(dirname $0); pwd)
mkdir -p $SCRIPT_DIR/../generated/$PLAYLIST_NAME
INPUT_DIR=$SCRIPT_DIR/../download/youtube/$PLAYLIST_NAME
OUTPUT_DIR=$SCRIPT_DIR/../generated/$PLAYLIST_NAME
FILES="$INPUT_DIR/*.mp4"
for FILEPATH in $FILES; do
	duration=$(ffprobe -v quiet -of default=noprint_wrappers=1:nokey=1 -show_entries format=duration "$FILEPATH")
	NAME=$(basename -- "$FILEPATH")
    EXTENSION="${NAME##*.}"
    NAME="${NAME%.*}"
    echo -e "$NAME"
    start_time=$(bc -l<<<"$duration*0.25")
    end_time=$(bc -l<<<"$duration*0.95")
    length_time=$(bc -l<<<"$end_time-$start_time")
    rate=$(bc -l<<<"($IMAGE_NUM-2)/$length_time")
    if LANG=C grep -q -n -v '^[[:cntrl:][:print:]]*$' <<< "$NAME" ; then
        name_format=$(echo "$NAME" | uconv -x "Fullwidth-Halfwidth")
        name_en=$(echo $(trans -brief -no-warn -no-ansi ja:en "$name_format") | sed -e "s/\./ /g" | sed -e "s/^The *//" | sed -e "s/^ *//" | sed -e "s/ *$//" | sed -e "s/  / /" | sed -e "s/#//" )
        NAME=$name_en
    fi
    echo "ffmpeg -ss $start_time -t $length_time -i \"$FILEPATH\" -r $rate \"$OUTPUT_DIR/$NAME%06d.jpg\""
    FFMPEG_RUNNING_THREADS="$(ps hf -opid,cmd -C "ffmpeg" | awk '$2 !~ /^[|\\]/ { ++n } END { print n }')"
    echo "----- ffmpeg threads:$FFMPEG_RUNNING_THREADS -----"
    while (($FFMPEG_RUNNING_THREADS >= $RUN_THREADS))
    do
    	FFMPEG_RUNNING_THREADS="$(ps hf -opid,cmd -C "ffmpeg" | awk '$2 !~ /^[|\\]/ { ++n } END { print n }')"
    done
    ffmpeg -ss $start_time -t $length_time -i "$FILEPATH" -r $rate "$OUTPUT_DIR/$NAME%06d.png" &
    echo "-----"
done