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• Black overlay appears when merging a transparent video to another video

  13 juin 2012, par RakeshS

  This is what I have done so far :

  Command to create a transparent PNG image :

  convert -size 640x480 -background transparent -fill blue \
  
  -gravity South label:ROCK image1-0.png

  Command to create a transparent video :

  ffmpeg -loop 1 -f image2 -i image1-0.png -r 20 -vframes 100 \
  
  -vcodec png -pix_fmt bgra mov-1.mov

  (as per this post) - I expect this video to be a transparent video.

  Command to overlay a video with another :

  ffmpeg -i final-video.mov -sameq -ar 44100 \
  
  -vf "movie=mov-1.mov [logo];[in][logo] overlay=0:0 [out]" \
  
  -strict experimental final-video.mov

  Above commands works perfect and I have not faced any problem, but I don't get what I expect which is kinda watermarking effect, I want mov-1.mov to be transparent with final-video.mov.

  Questions :

  1. Is there any way to verify if the generated video is transparent ? other than merging ?
  2. Not sure why the above mov-1.mov is not transparent when it is merged with final-video.mov, any info to solve this problem would be great.

  Please help.

• ffmpeg boxblur filter takes too long

  12 juin 2020, par Prashant_Sarin

  I am using below command to blur a video but it is very slow. Can anyone please help if i can improve the speed somehow.

  



  "ffmpeg -i $inputPath -lavfi [0:v]split=2[original][copy];[copy]scale=ih*16/9:-1,crop=h=iw*9/16,boxblur=luma_radius=50:chroma_radius=25:luma_power=2[blurred];[blurred][original]overlay=(main_w-overlay_w)/2:(main_h-overlay_h)/2[final] -map [final] -map a:0 -g 2 -preset ultrafast $outputPath -y"


  


• Trying to merge two videos from my photo roll with Flutter ffmpeg without success

  4 avril 2023, par Stéphane de Luca

  My goal is to merge too video I pick from my photo roll.
My code starts as follows :

  


  // videos[0] contains: "content://media/external/video/media/2779"
 final v1 = await videos[0].getMediaUrl();
    if (v1 == null) return;
    final v1Path = await LecleFlutterAbsolutePath.getAbsolutePath(uri: v1);


  


  But printing v1Pathgive a path with jpeg extension :
/data/user/0/com.example.shokaze/cache/OutputFile_1669939088711.jpeg' which I though would have bear mp4` as it is a video.

  


  Why is it so ?

  


  Another question I have is how can I make a relevant path so that the ffmpeg video appears in my roll after its creation ? Should I do the following and provide outputPathto the code ?

  


  The command it executes is :
-i /data/user/0/com.example.shokaze/cache/OutputFile_1669940421875.jpeg -i /data/user/0/com.example.shokaze/cache/OutputFile_1669940428723.jpeg -filter_complex '[0:0][1:0]concat=n=2:v=1:a=0[out]' -map '[out]' /data/user/0/com.example.shokaze/app_flutter/output.mp4

  


  And I get an error :
I/flutter (30190): error 1

  


  My code is as follows :

  


      String output = "content://media/external/video/media/output";
    final outputPath = await LecleFlutterAbsolutePath.getAbsolutePath(uri: output);
    if (outputPath == null) return;


  


  The full code is as follows :

  


  // Makes the final video by merging all videos from the mixing table
  void makeFinalVideo() async {
    if (videos.length < 2) return;

    final v1 = await videos[0].getMediaUrl();
    if (v1 == null) return;
    final v1Path = await LecleFlutterAbsolutePath.getAbsolutePath(uri: v1);
    if (v1Path == null) return;
    //String v1 = "";
    final v2 = await videos[1].getMediaUrl();
    if (v2 == null) return;
    final v2Path = await LecleFlutterAbsolutePath.getAbsolutePath(uri: v2);
    if (v2Path == null) return;
    String output = "content://media/external/video/media/output";
    final outputPath = "";
    // await LecleFlutterAbsolutePath.getAbsolutePath(uri: output);
    // if (outputPath == null) return;

    Video.merge(v1Path, v2Path, outputPath);
  }



class Video {
  /// Merges the video [v1] with [v2] as [output] video located in app doc path
  static void merge(String v1, String v2, String output) async {
    final appDocDir = await getApplicationDocumentsDirectory();

    //final appDir = await syspaths.getApplicationDocumentsDirectory();
    String rawDocumentPath = appDocDir.path;
    final outputPath = '$rawDocumentPath/output.mp4';

    final command =
        '-i $v1 -i $v2 -filter_complex \'[0:0][1:0]concat=n=2:v=1:a=0[out]\' -map \'[out]\' $outputPath';
    //await execute(command);
    try {
      final r = await FFmpegKit.execute(command);

      //.then((rc) => print("FFmpeg process exited with rc $rc"));
      print("Result: $r");
    } catch (e) {
      print("Exception: $e");
    }
  }
}