Materiale di Laboratorio di Informatica (SGI e SSE)
https://gdv.github.io/laboratorio-informatica
Registrato con profili Firefox di simplescreenrecorder e comando wmctrl -e 0,915,2,1920,1260 -r SAS\ Studio
Per vedere i tasti: screenkey -p fixed -g 1800x80+1000+50 -f "DejaVu Sans Mono Bold"
Per fare crop del video
ffmpeg -i zoom_0.mp4 -filter:v "crop=1866:1096" part1.mp4
ffmpeg -i DB-SAS2-to-crop-35.mp4 -filter:v "crop=1866:1096" -vcodec libx265 -crf 35 -acodec copy DB-SAS2-h265.mp4
Converti ffmpeg -ss 00:00:40 -i DB-SAS2.mp4 -i ~/Downloads/blank2.png -filter_complex "[0:v][1:v] overlay=1725:0:enable='between(t,0,5070)'" -vcodec libx265 -crf 28 -c:a copy DB-SAS2-to-crop.mp4
Una conversione più efficiente, in un formato libero
(https://www.draketo.de/software/ffmpeg-compression-vp9-av1.html)
Q=42; EXT="webm"
time for i in riscv_hammerblade.webm
do
nice ffmpeg -y -i "$i" -c:v libvpx-vp9 -b:v 0 -crf $Q
-aq-mode 2 -an
-tile-columns 0 -tile-rows 0
-frame-parallel 0 -cpu-used 8
-auto-alt-ref 1 -lag-in-frames 25 -g 999
-pass 1 -f webm -threads 8
"$(basename "$i" .${EXT})".temp;
nice ffmpeg -y -i "$i" -c:v libvpx-vp9 -b:v 0 -crf $Q
-aq-mode 2 -c:a libopus -b:a 12k
-tile-columns 2 -tile-rows 2
-frame-parallel 0 -cpu-used -5
-auto-alt-ref 1 -lag-in-frames 25
-pass 2 -g 999 -threads 8
"$(basename "$i" .${EXT})"-vp9-q${Q}.webm;
done
Per codificare in AV1 (troppo lento)
Q=56 && EXT="mkv" && time for i in *.${EXT}; do
nice ffmpeg -y -i "$i" -c:v libaom-av1 -strict -2
-b:v 0 -crf $Q
-aq-mode 2 -an
-sc_threshold 0
-row-mt 1 -tile-columns 2 -tile-rows 2 -threads 12
-cpu-used 8
-auto-alt-ref 1 -lag-in-frames 25 -g 999
-pass 1 -f webm
"$(basename "$i" .${EXT})"-av1.temp
nice ffmpeg -y -i "$i" -c:v libaom-av1 -strict -2
-b:v 0 -crf $Q -aq-mode 2
-sc_threshold 0
-row-mt 1 -tile-columns 2 -tile-rows 2 -threads 8
-cpu-used 1
-auto-alt-ref 1 -lag-in-frames 25 -g 999
-c:a libopus -b:a 12k
-pass 2 -threads 12
"$(basename "$i" .${EXT})"-av1-q${Q}-cpu-used-1.webm
# create a preview image to use as poster; position: 5s (-ss 5)
mplayer "$i" -ss 5 -nosound -vo jpeg:outdir=. -frames 1
mv 00000001.jpg "$(basename "$i" .${EXT})"-av1.jpg
done