[FFmpeg-user] newbie question: equivalent to UDP circular buffer overrun for -i /dev/video0 ?

[Ram Shaffir]

Hello,

Is there a way to keep/update just the last 30 seconds from a USB webcam video stream ‘-i /dev/video0’? if I understand correctly, ffmpeg keeps the last captured stream with the use of ‘overrun_nonfatal=1&fifo_size=xxxx ‘ and overruns the old data with the new as long as it runs, are those commands only apply to UDP stream?

I am using ffmpeg version:

ffmpeg version git-2020-05-20-86822cf Copyright (c) 2000-2020 the FFmpeg developers
  built with gcc 8 (Raspbian 8.3.0-6+rpi1)
  configuration: --extra-cflags=-I/usr/local/include --extra-ldflags=-L/usr/local/lib --extra-libs='-lpthread -lm' --arch=armel --enable-gmp --enable-gpl --enable-libaom --enable-libass --enable-libdav1d --enable-libdrm --enable-libfdk-aac --enable-libfreetype --enable-libkvazaar --enable-libmp3lame --enable-libopencore-amrnb --enable-libopencore-amrwb --enable-libopus --enable-librtmp --enable-libsnappy --enable-libsoxr --enable-libssh --enable-libvorbis --enable-libvpx --enable-libzimg --enable-libwebp --enable-libx264 --enable-libx265 --enable-libxml2 --enable-mmal --enable-nonfree --enable-omx --enable-omx-rpi --enable-version3 --target-os=linux --enable-pthreads --enable-openssl --enable-hardcoded-tables
  libavutil      56. 46.100 / 56. 46.100
  libavcodec     58. 86.100 / 58. 86.100
  libavformat    58. 43.100 / 58. 43.100
  libavdevice    58.  9.103 / 58.  9.103
  libavfilter     7. 82.100 /  7. 82.100
  libswscale      5.  6.101 /  5.  6.101
  libswresample   3.  6.100 /  3.  6.100
  libpostproc    55.  6.100 / 55.  6.100
Hyper fast Audio and Video encoder


Thank you all in advance,
Best,
Ram