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• Problems cropping videos with ffmpeg -ss -t

  8 décembre 2016, par Alex Bollbach

  I have been trying to figure out how to precisely crop out sub-sections of a video final.mp4, for example a cropped video with range [0.2, 0.28] or [9.1, 10.2]. So I’ve been using ffmpeg with -ss and -t options. The following command (or some similar form) is what I’ve seen prescribed :

  ffmpeg -y -i final.mp4 -ss 00:00:01 -t 00:00:01.5 -acodec copy -vcodec copy crop1.mp4

  What I expect is a cropped video of length 1.5 starting at time 1.0, but I get a broken video that doesn’t play. Or I’ll try :

  ffmpeg -y -i final.mp4 -ss 1 -c copy -t 1.5 crop1.mp4

  and get a video with the audio cropped to 1.5 seconds but the video lasting much longer freeze framed.

  The point is this should be a relatively straightforward operation but I’m running into problems at every turn. What is wrong with these commands ? My original video is a 7 minute youtube ripped mp4 which I trimmed down to 10 seconds (this seemed to work). But now further finer-grain trimming of that video is showing confusing behavior. Perhaps my video file is somehow in a bad state from the first trimming ?

• Flutter app crashes in release mode when initializing FlutterFFmpegConfig() ;

  18 février 2021, par Mahmoud Eidarous

  The app is working on Android on Debug mode(only) with no errors in the logcat/terminal.
But when I tested it on iOS (even in debug mode), it crashes on a specific page.
After long tests, I could know that this line was causing the app to crash.

  


  FlutterFFmpegConfig _flutterFFmpegConfig = FlutterFFmpegConfig();


  


  If I comment that line, the app won't crash, but I need that line to manipulate videos in the app.

  


  I'm using flutter_ffmpeg: ^0.3.0 in pubspec.yaml, and full-gpl package is set in android\build.gradle

  


  ext {
    flutterFFmpegPackage  = "full-gpl"
}


  


  Related package initializations code snippet :

  


  final FlutterFFmpegConfig _flutterFFmpegConfig = new FlutterFFmpegConfig();
final FlutterFFmpeg _flutterFFmpeg = new FlutterFFmpeg();
final FlutterFFprobe _flutterFFprobe = new FlutterFFprobe();


  


  I'm not sure, but it seems like the app can't handle creating all these objects at the same class !
Anyone familiar with this problem ?

  


• FFMPEG concatenate multiply files with various extensions and properties

  28 juillet 2022, par KRUK

  I'm trying to create a movie on Windows using ffmpeg from files that are from different devices and in different extensions (.mp4, .mov). Is there any way to combine any file extensions into one final movie that will play properly ?

  


  I'm thinking of such an approach, to first normalize all files to the same format (What is the recommended final format ?) and only then combine them into a final file.

  


  I am experimenting with this approach :

  


  ffmpeg -i [input.anyFormatX] outputX.mp4


  


  and then

  


  ffmpeg -f concat -i [List of files] output.mp4


  


  But unfortunately this does not work for all files, should pay attention to the codecs or maybe some other intermediate format ? The biggest problem appears with files recorded with Iphone and in extension .mov. After the first stage, these videos look overburnt, as if they have a lot of raised brightness, how to correct this ?

  


  Do you know perhaps any generic solution, which would allow the assembly of videos from different devices (including Iphone) and with different parameters such as frame rate or resolution ?