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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 ?

• ffmpeg scale filter takes too long

  17 juin 2020, par Prashant_Sarin

  I am using below command to scale and 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"


  


• Flutter Animated Thumbnails

  2 septembre 2020, par user433575

  I'm using the camera package to record videos and want to have animated thumbnails. I don't see any packages other than ffmpeg which might be able to do it but I'm stuck.

  


  I need to capture videos using the camera package, save them to mp4 and generate webp animated images from it. Any help or suggestions greatly appreciated.

  


  Here's some of my code :

  


      static Future<string> getThumb(videoPath, width, height) async {&#xA;assert(File(videoPath).existsSync());&#xA;&#xA;final String outPath = &#x27;$videoPath.webp&#x27;;&#xA;final arguments =&#xA;    &#x27;-y -i $videoPath -vcodec webp -loop 0 -pix_fmt yuv420p $outPath&#x27;;&#xA;&#xA;    &#xA;final int rc = await _encoder.execute(arguments);&#xA;assert(rc == 0);&#xA;assert(File(outPath).existsSync());&#xA;&#xA;return outPath;&#xA;</string>

  


  }

  


  Thanks