scottweston/ffmpeg repository overview

$ docker run --rm -it scottweston/ffmpeg
ffmpeg version 2.6.3 Copyright (c) 2000-2015 the FFmpeg developers
built with gcc 4.9.2 (Alpine 4.9.2)
configuration: --prefix=/usr --enable-avresample --enable-avfilter --enable-gnutls --enable-gpl --enable-libmp3lame --enable-librtmp --enable-libvorbis --enable-libvpx --enable-libxvid --enable-libx264 --enable-libtheora --enable-libv4l2 --enable-postproc --enable-pic --enable-pthreads --enable-shared --enable-x11grab --disable-stripping --disable-static --enable-vaapi --enable-libopus --disable-debug
libavutil      54. 20.100 / 54. 20.100
libavcodec     56. 26.100 / 56. 26.100
libavformat    56. 25.101 / 56. 25.101
libavdevice    56.  4.100 / 56.  4.100
libavfilter     5. 11.102 /  5. 11.102
libavresample   2.  1.  0 /  2.  1.  0
libswscale      3.  1.101 /  3.  1.101
libswresample   1.  1.100 /  1.  1.100
libpostproc    53.  3.100 / 53.  3.100
$

$ docker run -d --restart=always -v /var/www/html/outside.jpg:/data/output.jpg \
  scottweston/ffmpeg -nostdin -rtsp_transport udp -y -threads 1 -analyzeduration 30 \
    -i rtsp://rtsp-proxy/proxyStream-1 -r 1 -updatefirst 1 -f image2 \
    -s 1280x720 /data/output.jpg