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• avdevice/dshow : list_devices : show media type(s) per device

  21 décembre 2021, par Diederick Niehorster

  avdevice/dshow : list_devices : show media type(s) per device
  the list_devices option of dshow didn't indicate whether a specific
  
  device provides audio or video output. This patch iterates through all
  
  media formats of all pins exposed by the device to see what types it
  
  provides for capture, and prints this to the console for each device.
  
  Importantly, this now allows to find devices that provide both audio and
  
  video, and devices that provide neither.
  Signed-off-by : Diederick Niehorster <dcnieho@gmail.com>
  
  Reviewed-by : Roger Pack <rogerdpack2@gmail.com>
  

  • [DH] libavdevice/dshow.c

• In ffmpeg command-line, how to show all filter settings and their parameters before encoding ?

  7 décembre 2023, par F.X.

  Is there a way to force the ffmpeg command-line to display a comprehensive list of all filters and their parameters, even those that are applied automatically like -vf scale ?

  


  (EDIT : To clarify, I do not mean filter documentation, but rather displaying filters that are instantiated at runtime for a particular command-line, just before transcoding starts. The goal of this is mostly checking that ffmpeg is indeed doing the right thing and not inserting/changing filters when I do not intend it to.)

  


  There are a few options available, but none are comprehensive enough. For example :

  


  

  • The lavfi module has a dumpgraph option (here) but only if you're using lavfi.

  


  • The -sws_flags print_info option (here) can be used to determine if -vf scale is applied automatically and shows a subset of its parameters, but not all of them.

  


  


  Additionally, this question appears related the answer doesn't answer what I'm looking for.

  


  Are there better ways to achieve that ?

  


• FFMPEG show an Image with specific duration in filter_complex chain

  26 juin 2021, par Digerkam

  I have trouble with showing images with a specific duration in filter_complex.

  


  I have to use filter_complex, and getting error : "No such filter : 'duration'"

  


  So which filter do I need to use ?

  


  ffmpeg \
    -i "music.mp3" \
    -i "01.mp4" \
    -i "02.jpg" \
    -i "03.mp4" \
    -i "04.jpg" \
    -i "05.mp4" \
    -filter_complex " \
        [1:v]scale=300:400,trim=0:2,setpts=PTS-STARTPTS[v1]; \
        // Correct filter needed here: \
        [2:v]scale=300:400,duration=2,setpts=PTS-STARTPTS[v2]; \
        [3:v]scale=300:400,trim=4:6,setpts=PTS-STARTPTS[v3]; \
        // And here:
        [4:v]scale=300:400,duration=2,setpts=PTS-STARTPTS[v4]; \
        [5:v]scale=300:400,trim=8:10,setpts=PTS-STARTPTS[v5]; \
        [v1][v2][v3][v4][v5]concat=n=5:v=1:a=0[out] \
    " \
    -map "[out]" -map "0:a" -t "12" -c:v "libx264" -pix_fmt "yuv420p" -s "300x400" output.mp4