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• ffmpeg join multiple audio with acrossfade filter

  30 avril 2017, par alditis

  I have audio file multiple :

  001.ogg, 002.ogg, ..., 100.ogg

  I need join the files with overfade filter between they.

  I did it two in two a cumulative way :

  ffmpeg -i 001.ogg -i 002.ogg -filter_complex acrossfade=d=3:o=1:c1=tri:c2=tri -b:a 128k -o r01.ogg
  
  ffmpeg -i r01.ogg -i 003.ogg -filter_complex acrossfade=d=3:o=1:c1=tri:c2=tri -b:a 128k -o r02.ogg
  
  ffmpeg -i r02.ogg -i 004.ogg -filter_complex acrossfade=d=3:o=1:c1=tri:c2=tri -b:a 128k -o r02.ogg
  
  
  
  ....
  
  ffmpeg -i r98.ogg -i 100.ogg -filter_complex acrossfade=d=3:o=1:c1=tri:c2=tri -b:a 128k -o final.ogg

  But final.ogg does not have good sound on the firsts songs (less quality while more cumulative).

  How can I avoid less quality in the final.ogg ?

  Other way is concat but : How do you define the filter acrossfade using concat ?

  ffmpeg -i "concat:1.ogg|2.ogg|...|100.ogg" copy final.ogg

• ffmpeg cut video and burn subtitle in a single command

  3 janvier 2020, par razvan

  I want to cut a piece out of a video and burn subtitle in that piece.

  I can do this in 3 steps :

  1. cut the video
     ffmpeg -ss 25:00 -to 26:00 -i vid.mp4 -c copy out.mp4

  2. cut the subtitle
     ffmpeg -i sub.srt -ss 25:00 -to 26:00 out.srt

  3. burn subtitle in the video piece
     ffmpeg -i out.mp4  -vf subtitles=out.srt  -c:a copy -y final.mp4

  But I want to do this in a single ffmpeg command.

  If I do this
  ffmpeg -ss 25:00 -to 26:00 -i vid.mp4   -vf subtitles=sub.srt  -c:a copy -y final.mp4
  the video is cut but no subtitle is burned into it.
  This is fast.

  If I do this
  ffmpeg  -i vid.mp4  -ss 25:00 -to 26:00 -vf subtitles=sub.srt  -c:a copy -y final.mp4
  the video is cut and subtitles burned correctly,but there is a delay in starting writing the final.mp4.
  I think ffmpeg is processing vid.mp4 from the beginning till it reach the -ss time (and drop that part)
  then continue processing and writing it to final.mp4

  Is there a way to do this fast and in a single ffmpeg command ?
  Like ffmpeg going directly to -ss time and cut that, process it, burn subtitle in it.

  Thanks

• Is there a way to horizontal flip video captured from flutter front camera

  5 mai 2024, par JoyJoy

  Basically, I'm trying to flip video horizontally after capturing it from flutter front camera. So I start recording, stop recording, flip the video and pass it to another page. I'm fairly new and would appreciate any assistance as my code isn't working

  


  I've tried doing so using the new ffmpeg_kit flutter

  


  Future<void> flipVideo(String inputPath, String outputPath) async{&#xA;final ffmpegCommand = "-i $inputPath -vf hflip $outputPath";&#xA;final session = FFmpegKit.executeAsync(ffmpegCommand);&#xA;await session.then((session) async {&#xA;  final returnCode = await session.getReturnCode();&#xA;  if (ReturnCode.isSuccess(returnCode)) {&#xA;    print(&#x27;Video flipping successful&#x27;);&#xA;  } else {&#xA;    print(&#x27;Video flipping failed: ${session.getAllLogs()}&#x27;);&#xA;  }&#xA;});}&#xA;&#xA;void stopVideoRecording() async {&#xA;XFile videopath = await cameraController.stopVideoRecording();&#xA;&#xA;try {&#xA;  final Directory appDocDir = await &#xA;  getApplicationDocumentsDirectory();&#xA;  final String outputDirectory = appDocDir.path;&#xA;  final String timeStamp = DateTime.now().millisecondsSinceEpoch.toString();&#xA;  final String outputPath = &#x27;$outputDirectory/flipped_video_$timeStamp.mp4&#x27;;&#xA;&#xA;  await flipVideo(videopath.path, outputPath);&#xA;&#xA;  // Once completed,&#xA;   Navigator.push(&#xA;    context,&#xA;    MaterialPageRoute(&#xA;      builder: (builder) => VideoViewPage(&#xA;        path: File(outputPath),&#xA;        fromFrontCamera: iscamerafront,&#xA;        flash: flash,&#xA;      )));&#xA;  print(&#x27;Video flipping completed&#x27;);&#xA;} catch (e) {&#xA;  print(&#x27;Error flipping video: $e&#x27;);&#xA;}&#xA;</void>

  


  }