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• Flutter : Running FFmpeg.execute to generate thumbnails in a different isolate doesn't work ?

  12 novembre 2024, par Vasudev

  This is the current code to generate thumbnails for Video and Audio files.. It is working fine in most cases.

  


  @override&#xA;Future<imageprovider> thumbnail(String path,&#xA;{required double width, required double height}) async {&#xA;&#xA;&#xA;  final FFmpegSession session = await FFmpegKit.executeAsync(&#xA;          "-loglevel quiet -i &#x27;$filePath&#x27; -y -ss 00:00:00.000 -vframes 1 &#x27;$thumbnailPath&#x27;");&#xA;&#xA;&#xA;  final returnCode = await session.getReturnCode();&#xA;  if (returnCode == null || returnCode.isValueError()) {&#xA;    throw Exception("Thumbnail generation failed");&#xA;  }&#xA;&#xA;/* Returns ImageProvider */&#xA;}&#xA;</imageprovider>

  


  Now in iOS, for large files, the thumbnail generation doesn't really fail. But takes a long time and doesn't complete at all.

  


  This causes performance issues. I would like to run this FFmpeg.execute() in a different isolate, but it doesn't work at all.

  


    final FFmpegSession session = await Isolate.run(
    () async {
      return await FFmpegKit.executeAsync(
          "-loglevel quiet -i '$filePath' -y -ss 00:00:00.000 -vframes 1 '$thumbnailPath'");
    },
  );


  


• Xuggle IMediaWriter error

  10 décembre 2013, par prinsen

  Im testing xuggle and ran into a strange error. I have looked at the example in the documentation, and the xuggle-related code is identical. (http://www.xuggle.com/public/documentation/java/api/com/xuggle/mediatool/IMediaWriter.html)

  public class StorageServer {
  
  
  
  private final static String storage = "storage.mp4";
  
  private final static IMediaWriter writer = ToolFactory.makeWriter(storage);
  
  
  
  private final static Dimension dimension = new Dimension(320, 240);
  
  protected final static Logger logger = LoggerFactory.getLogger(StorageServer.class);
  
  
  
  public static void main(String[] args) {
  
  
  
      writer.addVideoStream(0, 0, ICodec.ID.CODEC_ID_MPEG4,
  
              320, 240);
  
      //setup the connection
  
      StreamServerAgent serverAgent = new StreamServerAgent(new StreamFrameListenerIMPL(), dimension);
  
      serverAgent.start(new InetSocketAddress("localhost", 1337));
  
  }
  
  
  
  
  
  protected static class StreamFrameListenerIMPL implements StreamFrameListener {
  
      private volatile long count = 0;
  
  
  
      @Override
  
      public void onFrameReceived(IVideoPicture image) {
  
          logger.info("frame received :{}", count++);
  
          if (count < 100) {
  
              logger.info("Writing frame");
  
              writer.encodeVideo(0, image);
  
          } else if (count > 220) {
  
              // writer.flush(); // doesn't matter
  
              writer.close();
  
          }
  
      }
  
  
  
  }

  When writer.close is called I get a runtime exception :

  Error: cannot write packet to read only container

  Which seems really strange..

• Create 256 color palette video

  2 mars 2020, par rlcabral

  I already have this working by converting the source video to GIF with :

  ffmpeg -y -t 5 source.mp4 -vf fps=10,scale=480:-1,smartblur=ls=-0.5,crop=iw:ih-2:0:0 -hide_banner -loglevel panic output.gif

  And then converting the GIF to MP4, like so :

  ffmpeg -y animated.gif -hide_banner -pix_fmt yuvj420p -loglevel panic -an -loglevel panic final.mp4

  What I want is to convert source.mp4 directly to final.mp4, and have the same 256 color palette as a normal GIF.

  I tried merging both commands together, and although it generates a MP4, the result is a 16 bit video, surprisingly smaller than a 8 bit video.

  Do I need to generate a palette first with palettegen and then re-encode the video with this palette ?