FFMPEG命令问题

我遇到了FFMPEG的问题。 确切地说,我试图从video文件中生成一些“有意义”的缩略图。 我在网上find了这个命令

ffmpeg -ss 3 -i input.mp4 -vf "select=gt(scene\,0.4)" -frames:v 5 -vsync vfr fps=fps=1/600 out%02d.jpg 

可悲的是,它不适合我,因为我得到:

 [NULL @ 0x86c2420] Unable to find a suitable output format for 'fps=fps=1/600' fps=fps=1/600: Invalid argument 

我试过在-vf里面加上 “fps = fps = 1/600” ,结果只产生一张图片。 我究竟做错了什么?

编辑:

这是一个完整输出的例子:

 $ ffmpeg -ss 3 -i video.ogg -vf "select=gt(scene\,0.4)" -frames:v 5 -vsync vfr fps=fps=1/600 out%02d.jpg ffmpeg version 2.5.3 Copyright (c) 2000-2015 the FFmpeg developers built on Jan 10 2015 23:26:13 with gcc 4.9.2 (GCC) 20141224 (prerelease) configuration: --prefix=/usr --disable-debug --disable-static --disable-stripping --enable-avisynth --enable-avresample --enable-fontconfig --enable-gnutls --enable-gpl --enable-libass --enable-libbluray --enable-libfreetype --enable-libfribidi --enable-libgsm --enable-libmodplug --enable-libmp3lame --enable-libopencore_amrnb --enable-libopencore_amrwb --enable-libopenjpeg --enable-libopus --enable-libpulse --enable-librtmp --enable-libschroedinger --enable-libspeex --enable-libtheora --enable-libv4l2 --enable-libvorbis --enable-libvpx --enable-libx264 --enable-libx265 --enable-libxvid --enable-runtime-cpudetect --enable-shared --enable-swresample --enable-vdpau --enable-version3 --enable-x11grab libavutil 54. 15.100 / 54. 15.100 libavcodec 56. 13.100 / 56. 13.100 libavformat 56. 15.102 / 56. 15.102 libavdevice 56. 3.100 / 56. 3.100 libavfilter 5. 2.103 / 5. 2.103 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 [theora @ 0x9b59140] 7 bits left in packet 82 [ogg @ 0x9b586e0] Broken file, keyframe not correctly marked. Last message repeated 2 times Input #0, ogg, from 'video.ogg': Duration: 00:09:56.46, start: 0.000000, bitrate: 2237 kb/s Stream #0:0: Video: theora, yuv420p, 854x480, 24 tbr, 24 tbn, 24 tbc Stream #0:1: Audio: vorbis, 48000 Hz, stereo, fltp, 192 kb/s [NULL @ 0x9b97660] Unable to find a suitable output format for 'fps=fps=1/600' fps=fps=1/600: Invalid argument 

我所要做的只是在“fps = fps = 1/600”之前加上-vf