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• Using FFmpeg in .net ?

  15 juillet 2016, par daniel

  So I know its a fairly big challenge but I want to write a basic movie player/converter in c# using the FFmpeg library. However, the first obstacle I need to overcome is wrapping the FFmpeg library in c#. I’ve downloaded ffmpeg but couldn’t compile it on Windows, so I downloaded a precompiled version for me. Ok awesome. Then I started looking for C# wrappers.

  I have looked around and have found a few wrappers such as SharpFFmpeg (http://sourceforge.net/projects/sharpffmpeg/) and ffmpeg-sharp (http://code.google.com/p/ffmpeg-sharp/). First of all, I wanted to use ffmpeg-sharp as its LGPL and SharpFFmpeg is GPL. However, it had quite a few compile errors. Turns out it was written for the mono compiler, I tried compiling it with mono but couldn’t figure out how. I then started to manually fix the compiler errors myself, but came across a few scary ones and thought I’d better leave those alone. So I gave up on ffmpeg-sharp.

  Then I looked at SharpFFmpeg and it looks like what I want, all the functions P/Invoked for me. However its GPL ? Both the AVCodec.cs and AVFormat.cs files look like ports of avcodec.c and avformat.c which I reckon I could port myself ? Then not have to worry about licencing.

  But I want to get this right before I go ahead and start coding. Should I :

  1. Write my own C++ library for interacting with ffmpeg, then have my C# program talk to the C++ library in order to play/convert videos etc.

  OR

  2. Port avcodec.h and avformat.h (is that all i need ?) to c# by using a whole lot of DllImports and write it entirely in C# ?

  First of all consider that I’m not great at C++ as I rarely use it but I know enough to get around. The reason I’m thinking #1 might be the better option is that most FFmpeg tutorials are in C++ and I’d also have more control over memory management than if I was to do it in c#.

  What do you think ?
  Also would you happen to have any useful links (perhaps a tutorial) for using FFmpeg ?

• How to accurately detect the start of the main beat and soundtracks in diverse audio tracks ?

  18 juin 2024, par SnoofFloof

  I'm working on a project where I need to edit soundtracks. The challenge is to detect when the main beat and melody of any given soundtrack is properly developed. I am certain there is better terminology to describe what I am aiming for, but ideally, I want to skip the "build-up" and immediately have the song starting at the "main part". This needs to work for various songs across different genres, which often have different structures and onset patterns, making it difficult to streamline the process.

  


  For example :

  


  https://www.youtube.com/watch?v=P77CNtHrnmI -> I would want to my code to identify the onset at 0:24

  


  https://www.youtube.com/watch?v=OOsPCR8SyRo -> Onset detection at 0:12

  


  https://www.youtube.com/watch?v=XKiZBlelIzc -> Onset detection at 0:19

  


  I've tried using librosa to analyze the onset strength and detect beats, but the current implementation either detects the very beginning of the song or fails to consistently identify when the beat is fully developed.

  


  This was my approach ;

  


  def analyze_and_edit_audio(input_file, output_file):
    y, sr = librosa.load(input_file)
    tempo, beat_frames = librosa.beat.beat_track(y=y, sr=sr)
    beat_times = librosa.frames_to_time(beat_frames, sr=sr)
    main_beat_start = beat_times[0]


  


  I have very little experience with librosa/audio editing, so I would appreciate any suggestions you might have !

  


• FFMPEG : Create timestamp based on actual creation time

  2 juillet 2022, par Peder Wessel

  Desired outcome

  


  Add overlay with timestamp for each frame of a video based on the original creation time for the video. E.g. starting at 2022-03-26T15:51:49.000000Z and a second later in the video present 2022-03-26T15:51.50.000000Z

  


  Approach

  


  Creation_time stored in the file already, e.g. when running ffmpeg -i input.mov" it presents creation_time   : 2022-03-26T15:51:49.000000Z.

  


  Adding overlay with timestamp to video :
ffmpeg -i input.mov -filter_complex "drawtext=text='%{pts\:gmtime\:1507046400\:%d-%m-%Y %T}': x=100 : y=100: box=1" -c:a copy output.mp4

  


  Challenge/ help needed

  


  Need to replace the gmtime\:1507046400 with the actual creation_time. How does one do it ?

  


  Sources

  


  

  • Overlay : https://superuser.com/questions/1013753/how-can-i-overlay-the-captured-timestamp-onto-a-video-using-ffmpeg-in-yyyy-mm-dd

  


  • Creation_time :
FFMPEG - Get creation and/or modification date