auto-convert to h265

My NAS has a lot of old privat video files and I want to convert them to the new h265-codec to save a lot of space. First thing to say is that you need a lot of CPU Power to process the video transcoding. Plan is to create a script that search the folder structure and then convert the file, remove the old (mov or mp4 file) and replace it with the new h265 encoded file.

After some research I got to following:
with help of Marcel in this post and Thomas Böhm

CPU rendering

find * -type f \( -iname \*.mp4 -o -iname \*.mov \) -exec ffmpeg -i {} -vcodec libx265 -crf 18 -vtag hvc1 temp_{} \; -exec mv temp_{} {} \;

If you just convert one file you use following command:

ffmpeg -i <path_to_orignal_file> -c:v libx265 -vtag hvc1 -crf 18 <path_to_output_file>

You can change the setting -crf to optimise you output files bitrate
If you want to know more about it visit Werner Robitza Homepage LINK

Apple T2 Chip – faster transcoding

If you use an Apple Mac Device with an T2 Chip (most OS devices after 2018) you can speed up the conversation a lot by using the hevc_videotoolbox of ffmpeg. This will increase the speed more than 30 times, compared to CPU rendering. BUT the quality is getting really bad. I would recommend to use the classical CPU rendering.

ffmpeg -i <path_to_orignal_file> -vcodec hevc_videotoolbox -vtag hvc1 -crf 18 <path_to_output_file>

After some testing and playing around I created following script. The logging is in englisch and german mixed, sorry for that.

You need to install ffmpeg and exiftool (this will help copy the metadata of the original video file to the new created one, so you do not lose the creation date). On a Mac you can use Homebrew to install the packages.

First install Homebrew:

/bin/bash -c "$(curl -fsSL https://raw.githubusercontent.com/Homebrew/install/HEAD/install.sh)"

then ffmpeg:

brew install ffmpeg

and now exiftool:

brew install exiftool

Now you can create a new shell script and copy the content into your empty file. Move the file to the folder which you want to transcode (take care the it will automatically do it recursive). Then you have to change the last line in the script to the folder path you have stored the script. Now you can start the transcoding with

chmod + x <your-script-name>
#and then
./<your-script-name>
#!/bin/zsh
# this script can help you to convert files in folders and subfolder to h265 files (using CPU rendering, you can change the ffmpeg parameters if you need)
# copy the script to the folder you want to convert files, and change the path in the last lines of the script
# you need ti have ffmpeg and exiftool installed. On the mac you can use Homebrew

mkdir ~/Documents/log

machwas() {
    wo_bin_ich=$( pwd )
    echo $date "bearbeite Ordner ${wo_bin_ich}/ -------" >> ~/Documents/log/H265_transcoding.log
    SAVEIFS=$IFS
    IFS=$(echo -en "\n\b")
    for f in *; do
        # fuer alle Ordner
        if [ -d "$f" ]; then
            echo $date "habe Ordner $f erkannt" >> ~/Documents/log/H265_transcoding.log
            (cd -- "$f" && machwas)
        fi
                if [ $(find $f -type f -maxdepth 0 -iname "*.mp4" -o -iname "*.mov"| wc -l) -gt 0 ]
                  then
                    echo $date $f 'is mov or mp4' >> ~/Documents/log/H265_transcoding.log
                    if mdls -name kMDItemCodecs $f | grep -q "HEVC"
                      then
                        echo $date $f 'is HEVC' >> ~/Documents/log/H265_transcoding.log
                      else
                        echo $date $f 'is not HEVC, starting to prozess the files ATTENTION' >> ~/Documents/log/H265_transcoding.log
  #                      echo $f
                        name=$(basename "$f")
  #                      echo $name
                        ffmpeg -i $f -vcodec libx265 -crf 18 -vtag hvc1 /tmp/$name >> ~/Documents/log/H265_transcoding.log
                        exiftool -tagsFromFile $f -api largefilesupport=1 -extractEmbedded -all:all -FileModifyDate -overwrite_original /tmp/$name >> ~/Documents/log/H265_transcoding.log
                        mv /tmp/$name $f
                      fi
                  else
                    echo $date $f ' this is not an video file of the type mp4 or mov' >> ~/Documents/log/H265_transcoding.log
                  fi
    done
}
    IFS=$SAVEIFS

# Aufruf des Ganzen
cd  /Users/admin/Movies
machwas

Maybe I will get time in the next weeks to change the language to english and optimize the workflow.

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