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• Flutter (Dart) : Record two videos, merge them and then view new video in gallery

  14 juin 2020, par Ittai Barkai

  I am aware that there already exists a solution to a very similar question, which can be found on the following link : Flutter/Dart : Find two video segments and merge them into a single valid video file ? However, being relatively new to Flutter (and programming in general) I cannot seem to replicate the desired result.

  



  My app is very simple and currently looks like this :

  



  

  



  I click on the button "Record Video" to record two videos, which are both successfully stored into the device's gallery. Using the Flutter image_picker and gallery_saver packages and the following piece of code :

  



      void _recordVideo() async {
    ImagePicker.pickVideo(source: ImageSource.camera)
        .then((File recordedVideo) {
      if (recordedVideo != null && recordedVideo.path != null) {
        setState(() {
          _buttonText = 'Saving in Progress...';
        });
        GallerySaver.saveVideo(recordedVideo.path).then((_) {
          setState(() {
            _buttonText = 'Video Saved!\n\nClick to Record New Video';
            if (_storedVideoOne == null) {
              _storedVideoOne = recordedVideo;
              print('video 1 stored');
            } else {
              _storedVideoTwo = recordedVideo;
              print('video 2 stored');
              _videoMerger();
            }
          });
        });
      }
    });
  }


  



  I can view these videos when I click on the button at the bottom "View Video From Gallery".

  



  Next I try to merge these two stored video files, using the flutter_ffmpeg package, as well as following the solution provided in the stack overflow question mentioned above. I try and do this using the following function I wrote :

  



  void _videoMerger() async {


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

    final FlutterFFmpeg _flutterFFmpeg = new FlutterFFmpeg();

        String commandToExecute = '-i ${_storedVideoOne.path} -i ${_storedVideoTwo.path} -filter_complex \'[0:0][1:0]concat=n=2:v=0:a=1[out]\' -map \'[out]\' outputPath';
        _flutterFFmpeg.execute(commandToExecute).then((rc) => print("FFmpeg process exited with rc $rc"));

  }


  



  But after running the function I do not seem to get a new combined video, which should be stored in outputPath and ideally also viewable in the gallery. Uploaded the Flutter project onto GitHub here :

  



  https://github.com/IttaiBarkai/Flutter-Video-Merger

  



  Any help would be greatly appreciated :)

  


• Strange "pause" in video after concatenation of two mp4 videos

  3 octobre 2016, par user606521

  I am concatenating two mp4 videos. The problem is that first video (intro.mp4) lasts 5 seconds, second video (output.mp4) lasts 2 seconds and video created by concatenating them lasts 9 seconds (and should last 5+2 = 7 seconds). In final.mp4 video the last frame from first video (intro.mp4) i shown for additional 2 seconds before second video (output.mp4) is played. It looks like a lag when watching video. What I am doing wrong ?

  list.txt :

  file 'data/intro.mp4'
  
  file 'output.mp4'

  command :

  ./bin/ffmpeg -f concat -i list.txt -c copy final.mp4

  output :

  ffmpeg version 2.7.2 Copyright (c) 2000-2015 the FFmpeg developers
  
    built with llvm-gcc 4.2.1 (LLVM build 2336.11.00)
  
    configuration: --prefix=/Volumes/Ramdisk/sw --enable-gpl --enable-pthreads --enable-version3 --enable-libspeex --enable-libvpx --disable-decoder=libvpx --enable-libmp3lame --enable-libtheora --enable-libvorbis --enable-libx264 --enable-avfilter --enable-libopencore_amrwb --enable-libopencore_amrnb --enable-filters --enable-libgsm --enable-libvidstab --enable-libx265 --disable-doc --arch=x86_64 --enable-runtime-cpudetect
  
    libavutil      54. 27.100 / 54. 27.100
  
    libavcodec     56. 41.100 / 56. 41.100
  
    libavformat    56. 36.100 / 56. 36.100
  
    libavdevice    56.  4.100 / 56.  4.100
  
    libavfilter     5. 16.101 /  5. 16.101
  
    libswscale      3.  1.101 /  3.  1.101
  
    libswresample   1.  2.100 /  1.  2.100
  
    libpostproc    53.  3.100 / 53.  3.100
  
  [mov,mp4,m4a,3gp,3g2,mj2 @ 0x7f8a6a80e600] Auto-inserting h264_mp4toannexb bitstream filter
  
  Input #0, concat, from 'list.txt':
  
    Duration: N/A, start: 0.000000, bitrate: 1296 kb/s
  
      Stream #0:0: Video: h264 (High) (avc1 / 0x31637661), yuv420p, 960x540, 1163 kb/s, 23.98 fps, 23.98 tbr, 11988 tbn, 47.95 tbc
  
      Stream #0:1: Audio: aac (LC) (mp4a / 0x6134706D), 48000 Hz, stereo, fltp, 133 kb/s
  
  [mp4 @ 0x7f8a6c006a00] Codec for stream 0 does not use global headers but container format requires global headers
  
  [mp4 @ 0x7f8a6c006a00] Codec for stream 1 does not use global headers but container format requires global headers
  
  Output #0, mp4, to 'final.mp4':
  
    Metadata:
  
      encoder         : Lavf56.36.100
  
      Stream #0:0: Video: h264 ([33][0][0][0] / 0x0021), yuv420p, 960x540, q=2-31, 1163 kb/s, 23.98 fps, 23.98 tbr, 11988 tbn, 11988 tbc
  
      Stream #0:1: Audio: aac ([64][0][0][0] / 0x0040), 48000 Hz, stereo, 133 kb/s
  
  Stream mapping:
  
    Stream #0:0 -> #0:0 (copy)
  
    Stream #0:1 -> #0:1 (copy)
  
  Press [q] to stop, [?] for help
  
  [mov,mp4,m4a,3gp,3g2,mj2 @ 0x7f8a6a80e600] Auto-inserting h264_mp4toannexb bitstream filter
  
  frame=  258 fps=0.0 q=-1.0 Lsize=     997kB time=00:00:09.84 bitrate= 829.5kbits/s    
  
  video:897kB audio:93kB subtitle:0kB other streams:0kB global headers:0kB muxing overhead: 0.634306%

• Strange "pause" in video after concatenation of two mp4 videos

  23 janvier 2021, par user606521

  I am concatenating two mp4 videos. The problem is that first video (intro.mp4) lasts 5 seconds, second video (output.mp4) lasts 2 seconds and video created by concatenating them lasts 9 seconds (and should last 5+2 = 7 seconds). In final.mp4 video the last frame from first video (intro.mp4) i shown for additional 2 seconds before second video (output.mp4) is played. It looks like a lag when watching video. What I am doing wrong ?

  



  list.txt :

  



  file 'data/intro.mp4'
file 'output.mp4'


  



  command :

  



  ./bin/ffmpeg -f concat -i list.txt -c copy final.mp4


  



  output :

  



  ffmpeg version 2.7.2 Copyright (c) 2000-2015 the FFmpeg developers
  built with llvm-gcc 4.2.1 (LLVM build 2336.11.00)
  configuration: --prefix=/Volumes/Ramdisk/sw --enable-gpl --enable-pthreads --enable-version3 --enable-libspeex --enable-libvpx --disable-decoder=libvpx --enable-libmp3lame --enable-libtheora --enable-libvorbis --enable-libx264 --enable-avfilter --enable-libopencore_amrwb --enable-libopencore_amrnb --enable-filters --enable-libgsm --enable-libvidstab --enable-libx265 --disable-doc --arch=x86_64 --enable-runtime-cpudetect
  libavutil      54. 27.100 / 54. 27.100
  libavcodec     56. 41.100 / 56. 41.100
  libavformat    56. 36.100 / 56. 36.100
  libavdevice    56.  4.100 / 56.  4.100
  libavfilter     5. 16.101 /  5. 16.101
  libswscale      3.  1.101 /  3.  1.101
  libswresample   1.  2.100 /  1.  2.100
  libpostproc    53.  3.100 / 53.  3.100
[mov,mp4,m4a,3gp,3g2,mj2 @ 0x7f8a6a80e600] Auto-inserting h264_mp4toannexb bitstream filter
Input #0, concat, from 'list.txt':
  Duration: N/A, start: 0.000000, bitrate: 1296 kb/s
    Stream #0:0: Video: h264 (High) (avc1 / 0x31637661), yuv420p, 960x540, 1163 kb/s, 23.98 fps, 23.98 tbr, 11988 tbn, 47.95 tbc
    Stream #0:1: Audio: aac (LC) (mp4a / 0x6134706D), 48000 Hz, stereo, fltp, 133 kb/s
[mp4 @ 0x7f8a6c006a00] Codec for stream 0 does not use global headers but container format requires global headers
[mp4 @ 0x7f8a6c006a00] Codec for stream 1 does not use global headers but container format requires global headers
Output #0, mp4, to 'final.mp4':
  Metadata:
    encoder         : Lavf56.36.100
    Stream #0:0: Video: h264 ([33][0][0][0] / 0x0021), yuv420p, 960x540, q=2-31, 1163 kb/s, 23.98 fps, 23.98 tbr, 11988 tbn, 11988 tbc
    Stream #0:1: Audio: aac ([64][0][0][0] / 0x0040), 48000 Hz, stereo, 133 kb/s
Stream mapping:
  Stream #0:0 -> #0:0 (copy)
  Stream #0:1 -> #0:1 (copy)
Press [q] to stop, [?] for help
[mov,mp4,m4a,3gp,3g2,mj2 @ 0x7f8a6a80e600] Auto-inserting h264_mp4toannexb bitstream filter
frame=  258 fps=0.0 q=-1.0 Lsize=     997kB time=00:00:09.84 bitrate= 829.5kbits/s    
video:897kB audio:93kB subtitle:0kB other streams:0kB global headers:0kB muxing overhead: 0.634306%