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• Modify code so each snippets start from begin instead end

  13 décembre 2022, par Ohiowizard

  source : https://davidwalsh.name/video-preview#comment-515168
  
the part of code that trim videos into snippets :

  


   # Loop and generate video snippets
    mkdir $tempdir
    interval=$(($length/$desiredsnippets-$starttimeseconds))
    for i in $(seq 1 $desiredsnippets)
    do
        # Format the second marks into hh:mm:ss format
        start=$(($(($i*$interval))+$starttimeseconds))
        formattedstart=$(printf "%02d:%02d:%02d\n" $(($start/3600)) $(($start%3600/60)) $(($start%60)))
        echo 'Generating preview part ' $i $formattedstart
        # Generate the snippet at calculated time
        ffmpeg -i $sourcefile -vf scale=$dimensions -preset fast -qmin 1 -qmax 1 -ss $formattedstart -t $snippetlengthinseconds -threads $(nproc) $tempdir/$i.mp4
    done


  


  `

  


  Video length is 3600 (60mins)
  
Desired snippets = 30, that mean 2mins each
  
It always start at 0:02:00 to 0:04:00 -> and so on
  
but i want it start at 0:00:00 (1st snippet) -> 0:02:00 (2nd snippet) -> (this put in code because it said invalid code format)

  


  

  • I want to make it trim from start of each snippets instead end of each snippets.

  


  • This code trim video into multiple parts(snippets) that set by user, and then merged all snippets into one video.

  


  


• How to debug ffmpeg c code used in IJKmediaplayer ?

  15 août 2015, par Daniyal Yasin

  I am trying to use the libstagefright codec of ffmpeg to decode an mp4 file using IJKmediaplayer on android. IJKmediaplayer is sort of a wrapper enabling the use of ffmpeg on Android.

  This is the link giving basic info about ijkmediaplayer : https://github.com/Bilibili/ijkplayer

  The link also describes the build process for ijkmediaplayer. First ffmpeg is built then the shared libraries are copied to appropriate places and then I have to import the project in eclipse.

  I use the ijkmediaplayer android project in eclipse as a library project in another android application. The structure is like this :

  |-ijkmediaplayer
  
  | |-jni
  
  |   |-ffmpeg (this folder doesn't have the complete source just headers)
  
  |   |-ijkmedia (some c source files of ijkmediaplayer)
  
  |
  
  |-my_project

  So my question is how do I debug libstagefright.cpp from my application ?

  Libstagefright.cpp is contained in the ffmpeg source not visible in the android ijkmediaplayer project. But used when building the ijkmediaplayer android project as described in the link.

  The debugger easily reaches the code of the ijkmediaplayer android project. But does not proceed to the native code automatically if I press f5.

• FFMPEG — Create New Audio File using aselect filter API call in C code

  17 juin 2021, par AfricanMamba

  I have been working on an a program in C that invokes the use of FFMPEG's libraries to remove some segments of audio from a given audio file. I have created the filter successfully using the API call, const AVFilter* aselect = avfilter_get_by_name("aselect"), linking it with abuffersrc and abuffersink.

  


  However, I am not sure entirely sure what to pass in to the arguments when creating the filter because when I pass in the argument string, "'between(t,10,32)', asetpts = N/SR/TB output.wav", it gives me an error saying : "Invalid chars ',asetpts=N/SR/TBoutput.wav' at the end of expression"

  


  But when I pass in just "'between(t,10,32)'" as the arguments for the filter, the program compiles and runs but no output file is created with just the audio from 10 seconds to 32 seconds. Does anyone happen to know if it is even possible to use the aselect filter API to create new audio files or if there is an example that exists showing how to copy only frames from one audio file to another ? Thanks !