ffmpeg cam

 

ffmpeg /dev/video0

ffmpeg -f v4l2 -list_formats all -i /dev/video0

ffplay -f v4l2 -list_formats all /dev/video0

arecord -l

cat /proc/asound/cards

hw:1,0

lsusb -v | grep 'tSamFreq'

arecord -f S16_LE -c 2  -D "hw:1,0" a-001

ffplay -f alsa -i hw:1,0

ffplay -f v4l2 -video_size 1920x1080 -framerate 30 /dev/video0

ffplay -f v4l2 -video_size 1280x720 -framerate 30 /dev/video0

ffplay -f v4l2 -video_size 1366x768 -framerate 30 /dev/video0

ffmpeg -f v4l2 -framerate 30 -video_size 1920x1080 -c:v mjpeg -i /dev/video0 -c:v copy output.mov

ffmpeg -f v4l2 -framerate 30 -c:v mjpeg -i /dev/video0 -c:v copy output.mkv

ffmpeg -f v4l2 -framerate 30 -c:v mjpeg -i /dev/video0 -f alsa -i hw:1,0 -c:v copy -c:a copy  output.mkv

ffmpeg -f v4l2 -framerate 30 -c:v mjpeg -i /dev/video0 -f alsa -i hw:1,0 -c copy  output.mkv

ffmpeg -f v4l2 -framerate 30 -c:v mjpeg -i /dev/video0 -f alsa -i hw:1,0 -c copy -f rawvideo  - | ffplay -

ffmpeg -f v4l2 -framerate 30 -c:v mjpeg -i /dev/video0 -f alsa -i hw:1,0 -c copy -f avi  - | ffplay -

ffplay -f v4l2 -framerate 30   /dev/video0 

vlc v4l2:///dev/video0 --input-slave=alsa://hw1,0 --alsa-samplerate=96000

bluetooth

 

/usr/local/etc/init.d/bluez status

pulseaudio

bluetoothctl power on

bluetoothctl agent on

bluetoothctl

  scan on

  scan off

bluetoothctl devices

bluetoothctl info

bluetoothctl remove xx:xx:xx:xx:xx:xx

bluetoothctl trust      xx:xx:xx:xx:xx:xx

bluetoothctl pair        xx:xx:xx:xx:xx:xx

bluetoothctl connect xx:xx:xx:xx:xx:xx

bluetoothctl info        xx:xx:xx:xx:xx:xx

pactl list sinks | grep Name:

pactl set-default-sink bluez_sink.xx_xx_xx_xx_xx_xx.a2dp_sink

pactl -- set-sink-volume 1 -10%

pactl -- set-sink-volume 1 +10%

pactl -- set-sink-volume 1 10%

pactl -- set-sink-volume 1 50%

jdk ssl/tls

1.7 default tls1

-Dhttps.protocols=SSLv3,TLSv1,TLSv1.1,TLSv1.2

-Djavax.net.debug=ssl

1.8 default tls1.2

mobile browser request retry - idempotent requests

https://groups.google.com/a/chromium.org/g/chromium-dev/c/urswDsm6Pe0

https://www.w3.org/Protocols/rfc2616/rfc2616-sec10.html

https://aws.amazon.com/builders-library/making-retries-safe-with-idempotent-APIs/

https://answers.sap.com/questions/13359226/preventing-http-retry-requests-eg-via-approuter.html

zip filename encode (non-UTF8)

LC_CTYPE=zh_TW.big5 7z x file.zip

LC_CTYPE=zh_TW.big5 busybox unzip file.zip

TODO: filename in big5

ls -i 

find . -inum 12321475 -exec mv {} new-filename \;

find . -inum 12321475 -print0 | xargs -0 mv -t new-filename

wmctrl / xdotool - XWindow move resize

 

wmctrl

wmctrl -d

wmctrl -l

wmctrl -i -a <win id>

wmctrl -i -r <win id> 0,x,y,w,h

wmctrl -lx

0x00a00002  1 aterm.XTerm           box Terminal

0x01000002  1 google-chrome.Google-chrome  box WeChat/Weixin for Web - Google Chrome

0x01000005  1 google-chrome.Google-chrome  box about:blank - Google Chrome

0x01000006  1 google-chrome.Google-chrome  box QR-slot.png (500×500) - Google Chrome

google

wmctrl -i -r 0x01000005 -e 0,150,40,1000,800

wechat

wmctrl -i -r 0x01000002 -e 0,0,140,900,800

xdotool

xdotool search wechat

xdotool search ""

Linux traffic control

 sudo tc qdisc add dev eth0 root netem delay 200ms

sudo tc qdisc del dev eth0 root netem delay 200ms

sudo tc qdisc add dev eth0 root netem delay 1000ms

sudo tc qdisc del dev eth0 root netem delay 1000ms

sudo tc qdisc del dev eth0 root netem delay 2000ms