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• How to add dynamic captions with animations on a video in a cross-platform Android & iOS app and export it as a final video ? [closed]

  29 avril, par Danial Qsk

  I'm building a cross-platform mobile app using Flutter (or React Native) where users can :

  


  Add dynamic text captions with animations over a video, similar to TikTok

  


  See these changes in real-time during video playback

  


  Export the video with the animated captions burned into the output (e.g., MP4)

  


  What I’ve implemented so far :

  


  Video playback using video_player in Flutter (or react-native-video).

  


  Captions are rendered using Canvas/UI layer during playback.

  


  Problem : While I can overlay animated text in the UI, I can't figure out how to include these in the exported video. I’m considering using FFmpeg to burn in the captions, but I’m unclear how to integrate it with the animated UI overlays or render them into a final video on both Android and iOS.

  


  What I want to achieve :

  


  Efficient way to render animated text overlays onto a video and export it as a final video file on both Android and iOS.

  


  Maintain good performance for real-time playback and smooth export.

  


  What approaches or processing pipelines could achieve this ?
(For example, rendering the UI layer to an offscreen video, integrating with FFmpeg, or using native rendering techniques.)

  


• optimizing ffmpeg in windows platform for processing with web-cam

  22 août 2013, par user2320537

  I have to develop a tool in java that will capture frames from webcam, Now what I have done for that is, I have used Runtime class to run ffmpeg and other commands, when it starts capturing frames from my web-cam,
  I am using following method for that.

  public class FFMPEGClass {
  
  
  
      private String ffmpegExeLocation, line;
  
      private final String FRAME_DIGITS = "010";
  
  
  
      public FFMPEGClass(String capturingDName, String outputImagesLocation, int framesPerSecond) {
  
          ffmpegExeLocation = System.getProperty("user.dir") + "\\bin\\";
  
          System.out.println(ffmpegExeLocation);
  
          try {            
  
              System.out.println(ffmpegExeLocation + "ffmpeg -t 100000 "
  
                      + "-f vfwcap -s 640x480 -i 0 -r 1/" + framesPerSecond + " -f image2 " + outputImagesLocation + "\\camera%"+FRAME_DIGITS+"d.jpg");
  
              Process pp = Runtime.getRuntime().exec(ffmpegExeLocation + "ffmpeg -t 100000 "
  
                      + "-f vfwcap -s 640x480 -i 0 -r 1/" + framesPerSecond + " -f image2 " + outputImagesLocation + "\\camera%"+FRAME_DIGITS+"d.jpg");
  
              BufferedReader br = new BufferedReader(new InputStreamReader(pp.getErrorStream()));
  
              while((line = br.readLine()) != null){
  
                   System.out.println(line);
  
              }
  
          } catch (Exception ex) {
  
              ex.printStackTrace();
  
          }
  
      }
  
  }

  In my case capturingDName is USB2.0 UVC VGA WebCam
  outputImagesLocation is e :\myfolder\frames and
  framesPerSecond is 10

  This code works well but it is unable to capture frames efficiently, In other words I want to say that its processing is very slow, can anyone please tell that how can I optimize it so that it can capture frames very fastly.

  I have Intel Core i3 processor with 6 GB of RAM

  I have already checked many answers from google and stackoverflow but these are not working in my case

• Applying same filter_complex many times before output [duplicate]

  19 août 2019, par Fabián

  This question already has an answer here :

  • FFmpeg command to apply multiple filters and limit the final file size [closed]
    
    1 answer
    
  • Applying multiple filters at once with FFMPEG
    
    2 answers
    
  • FFMpeg - Combine multiple filter_complex and overlay functions
    
    1 answer
    
  • ffmpeg : multiple video filter order issue
    
    1 answer
    

  It’s not a duplicate. This is about using filter_complex, not -vf.

  In my video there’s an object that has shades of yellow (more orange-like) and a solid yellow as background.

  I need to output all frames into a png sequence, using a color key filter to replace the yellow from the background :

  ffmpeg -ss 4 -i original.mp4 -t 2 -filter_complex "[0:v]colorkey=0xfff31b:0.125:0[ckout]" -map "[ckout]" colorkey-%d.png

  This removes the specific color, but leaves some pints behind, and some items are yellow-themed, so blending value is a no-no for this scenario.

  I need to get rid of 4 specific yellow-colors from the frames : 0xfff31b, 0xfae56b, 0xfaec46 and 0xeee2a0, and I plan to run the same filter for specific colors before getting the final result.

  So first I tried this :

  ffmpeg -ss 4 -i original.mp4 -t 2 -filter_complex "[0:v]colorkey=0xfff31b:0.4:0[ckout1];[0:v]colorkey=0xfae56b:0.4:0[ckout2];[0:v]colorkey=0xfaec46:0.4:0[ckout3];[0:v]colorkey=0xeee2a0:0.4:0[ckout4]" -map "[ckout4]" colorkeyrefined-%d.png

  Then this :

  ffmpeg -ss 4 -i original.mp4 -t 2 -filter_complex "[0:v]colorkey=0xfff31b:0.4:0[ckout]" -filter_complex "[0:v]colorkey=0xfae56b:0.4:0[ckout]" -filter_complex "[0:v]colorkey=0xfaec46:0.4:0[ckout]" -filter_complex "[0:v]colorkey=0xeee2a0:0.4:0[ckout]" -map "[ckout]" colorkeyrefined-%d.png

  But both display the same error :

  Filter colorkey has an unconnected output.

  Is there a way to apply the colorkey feature 4 times (with the mentioned values) in one go ?