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• How to create bash script with ffmpeg to flip a dir of vids 180, then stitch together without losing vid length

  25 septembre 2022, par Maude Rozencrance's Cat

  I'm trying to make a bash script in linux to flip a bunch of AVI files 180 degrees, then stitch them together without losing the length of the vids. My code works, but it truncates each vid and makes 60 10sec vids, which should be 600 seconds of video, down to about 11 seconds.

  


  I removed the transpose to flip the vids and now I'm getting the correct vid length. So it works, but I have to flip the vid in the video player.

  


  >videos.txt

files=DSCF*.AVI

for f in $files
do
    #make list of vids, copy to videos.txt
    echo "file '$f'" >> videos.txt;
    echo "duration 10.0" >> videos.txt;
    
done

#stitch all vids together
ffmpeg -f concat -safe 0 -i videos.txt -c copy bigvid.AVI


  


• ffmpeg horizonal flip makes video shorter

  26 mai 2020, par Adam Gosztolai

  I am trying to use the following command to flip my video horizontally

  



  ffmpeg -i video.mp4 -vf hflip -c:a copy video_flip.mp4


  



  However, I discovered that it makes the video shorter, which I did not intend.

  



  I originally created the video using FFMpegWriter in Python, the code looks something like this

  



  metadata = dict(title='video', artist='me', comment='Watch this!')
writer = FFMpegWriter(fps=25, metadata=metadata)
with writer.saving(fig, "video.mp4", 100):
    for t in range(100):
        ax.cla()        
        ax.plot(x,y)

        writer.grab_frame()


  



  What am I doing wrong ?

  


• ffmpeg flip horizontally webcam to virtual video camera

  30 mai 2023, par Kaiser Schwarcz

  I need to horizontally flip my webcam image for a meeting.
I tried the instructions in this site https://wiki.archlinux.org/index.php/Webcam_setup#Applications which uses v4l2 and v4l2loopback to generate a virtual camera.

  


  # modprobe v4l2loopback


  


  Check the name of the newly created camera :

  


  $ v4l2-ctl --list-devices

Dummy video device (0x0000) (platform:v4l2loopback-000):
       /dev/video1


  


  Then you can run ffmpeg to read from your actual webcam (here /dev/video0) and invert it and feed it to the virtual camera :

  


  $ ffmpeg -f v4l2 -i /dev/video0 -vf "vflip" -f v4l2 /dev/video1


  


  You can use the "Dummy" camera in your applications instead of the "Integrated" camera.

  


  With these settings I was successful in vertically flipping my video. But that is not what I want. I want it to be flipped horizontally.

  


  So I tried this :

  


  $ ffmpeg -f v4l2 -i /dev/video0 -vf **"hflip"** -f v4l2 /dev/video1


  


  But I then I get no image from my cam.

  


  What am I doing wrong ?

  


  I'm using Fedora 31 in a desktop.

  


  COMPLETE LOG :

  


  ffmpeg version 4.2.2 Copyright (c) 2000-2019 the FFmpeg developers

  built with gcc 9 (GCC)

  configuration: --prefix=/usr --bindir=/usr/bin --datadir=/usr/share/ffmpeg --docdir=/usr/share/doc/ffmpeg --incdir=/usr/include/ffmpeg --libdir=/usr/lib64 --mandir=/usr/share/man --arch=x86_64 --optflags='-O2 -g -pipe -Wall -Werror=format-security -Wp,-D_FORTIFY_SOURCE=2 -Wp,-D_GLIBCXX_ASSERTIONS -fexceptions -fstack-protector-strong -grecord-gcc-switches -specs=/usr/lib/rpm/redhat/redhat-hardened-cc1 -specs=/usr/lib/rpm/redhat/redhat-annobin-cc1 -m64 -mtune=generic -fasynchronous-unwind-tables -fstack-clash-protection -fcf-protection' --extra-ldflags='-Wl,-z,relro -Wl,--as-needed -Wl,-z,now -specs=/usr/lib/rpm/redhat/redhat-hardened-ld ' --extra-cflags=' ' --enable-libopencore-amrnb --enable-libopencore-amrwb --enable-libvo-amrwbenc --enable-version3 --enable-bzlib --disable-crystalhd --enable-fontconfig --enable-frei0r --enable-gcrypt --enable-gnutls --enable-ladspa --enable-libaom --enable-libdav1d --enable-libass --enable-libbluray --enable-libcdio --enable-libdrm --enable-libjack --enable-libfreetype --enable-libfribidi --enable-libgsm --enable-libmp3lame --enable-nvenc --enable-openal --enable-opencl --enable-opengl --enable-libopenjpeg --enable-libopus --enable-libpulse --enable-librsvg --enable-libsrt --enable-libsoxr --enable-libspeex --enable-libssh --enable-libtheora --enable-libvorbis --enable-libv4l2 --enable-libvidstab --enable-libvmaf --enable-libvpx --enable-libx264 --enable-libx265 --enable-libxvid --enable-libzimg --enable-libzvbi --enable-avfilter --enable-avresample --enable-postproc --enable-pthreads --disable-static --enable-shared --enable-gpl --disable-debug --disable-stripping --shlibdir=/usr/lib64 --enable-libmfx --enable-runtime-cpudetect

  libavutil      56. 31.100 / 56. 31.100

  libavcodec     58. 54.100 / 58. 54.100

  libavformat    58. 29.100 / 58. 29.100

  libavdevice    58.  8.100 / 58.  8.100

  libavfilter     7. 57.100 /  7. 57.100

  libavresample   4.  0.  0 /  4.  0.  0

  libswscale      5.  5.100 /  5.  5.100

  libswresample   3.  5.100 /  3.  5.100

  libpostproc    55.  5.100 / 55.  5.100

Input #0, video4linux2,v4l2, from '/dev/video0':

  Duration: N/A, start: 233168.222502, bitrate: 147456 kb/s

    Stream #0:0: Video: rawvideo (YUY2 / 0x32595559), yuyv422, 640x480, 147456 kb/s, 30 fps, 30 tbr, 1000k tbn, 1000k tbc

Stream mapping:

  Stream #0:0 -> #0:0 (rawvideo (native) -> rawvideo (native))

Press [q] to stop, [?] for help

Output #0, video4linux2,v4l2, to '/dev/video2':

  Metadata:

    encoder         : Lavf58.29.100

    Stream #0:0: Video: rawvideo (Y42B / 0x42323459), yuv422p, 640x480, q=2-31, 147456 kb/s, 30 fps, 30 tbn, 30 tbc

    Metadata:

    encoder         : Lavc58.54.100 rawvideo

frame=   31 fps=0.0 q=-0.0 size=N/A time=00:00:01.03 bitrate=N/A dup=16 drop=0 sframe=   46 fps= 46 q=-0.0 size=N/A time=00:00:01.53 bitrate=N/A dup=16 drop=0 sframe=   61 fps= 40 q=-0.0 size=N/A time=00:00:02.03 bitrate=N/A .....