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• Extract frame at x time and crop [duplicate]

  31 mars 2019, par Thaison Nguyen

  This question already has an answer here :

  • FFmpeg stucks for few seconds on start
    
    1 answer
    

  I use the following cmd line to extract a frame at a certain timestamp and crop the image for analysis

  ffmpeg -i nba2.mp4 -ss 00:00:02 -vf "crop=in_w:in_h/6:0:in_h*.85" -vframes 1 out.png

  I get it just fine at 2 seconds, but the farther I go out, the longer it takes. It takes over 1 minute to extract a frame at 14 minutes and 30 seconds (00:14:30).

  ffmpeg -i nba2.mp4 -ss 00:14:30 -vf "crop=in_w:in_h/6:0:in_h*.85" -vframes 1 out.png

  This is a HD video, it appears that FFMPEG is looping through each frame to get to 00:14:30, is there a way to improve this efficiency ?

• parallel ffmpeg filter complex pipelines

  3 septembre 2021, par Paul Eppner

  Is there a possibility to run ffmpeg filter_complex filter in parallel pipelines ?
On the page http://trac.ffmpeg.org/wiki/Creating%20multiple%20outputs you can find an example under the heading "One filtering instance per each output". However, the filters mentioned there (boxblur,negate,yadif) are executed one after the other, although they could also all be executed simultaneously. I have quite complex filters and therefore long delays when the filters are executed one after the other.

  


  I hope there is another solution.
Cheers

  


  ---

  


  A few hours later I realised that the delay was probably not due to the pipeline, but to the analysis of the imports. However, I then only use the video and audio of the 1st stream. nevertheless, the delay time is then enormously high. Are there any ideas on how I can prevent this delay ?

  


      -i "rtmp://127.0.0.1:1935/$app/$name-de" \
    -i "rtmp://127.0.0.1:1935/$app/$name-en" \
    -i "rtmp://127.0.0.1:1935/$app/$name-fr" \
    -i "rtmp://127.0.0.1:1935/$app/$name-es" \
    -i "rtmp://127.0.0.1:1935/$app/$name-it" \
    -i "rtmp://127.0.0.1:1935/$app/$name-de" \
    -i "rtmp://127.0.0.1:1935/$app/$name-en" \
    -i "rtmp://127.0.0.1:1935/$app/$name-fr" \
    -i "rtmp://127.0.0.1:1935/$app/$name-es" \
    -i "rtmp://127.0.0.1:1935/$app/$name-it" \
    -i "rtmp://127.0.0.1:1935/$app/$name-de" \
    -i "rtmp://127.0.0.1:1935/$app/$name-en" \
    -i "rtmp://127.0.0.1:1935/$app/$name-fr" \
    -i "rtmp://127.0.0.1:1935/$app/$name-es" \
    -i "rtmp://127.0.0.1:1935/$app/$name-it" \
    -vsync -1 \
    -map 0:v -c:v:0 copy \
    -map 0:a \
    -c:a aac -ar 48000 \...```


  


• MobileVlcKit compiling Failed

  25 février 2016, par Bittoo

  Hi i am trying to use MobileVLCKit.For that i am using cocoapads like below
  pod ’MobileVLCKit’

  pod 'MobileVLCKit'

  then i compile my project it is showing plenty of errors below is my error Log

    NOTE: a missing vtable usually means the first non-inline virtual member function has no definition.
  
  ld: symbol(s) not found for architecture x86_64
  
  clang: error: linker command failed with exit code 1 (use -v to see invocation)
  
  
  
  "std::basic_string, std::allocator >::find(wchar_t const*, unsigned long, unsigned long) const", referenced from:
  
    TagLib::String::find(TagLib::String const&, int) const in MobileVLCKit(tstring.cpp.o)
  
    TagLib::String::split(TagLib::String const&) const in MobileVLCKit(tstring.cpp.o)
  
  
  
    dash::mpd::BasicCMParser::parseCommonAttributesElements(dash::xml::Node*, dash::mpd::CommonAttributesElements*, dash::mpd::CommonAttributesElements*) const in MobileVLCKit(libdash_plugin_la-BasicCMParser.o)

  I tried with architecture x86_64 but still showing lot of errors. I don’t know how to clear these errors.so can any body please help me