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• avformat_write_header() doesn't work when writing data to memory instead of file

  12 novembre 2020, par Mohamed Kandeel

  i want to resample a given input format from memory to memory everything is good so far.

  


  but when trying to get the output header from ffmpeg it doesn't work.

  


  here i allocate the context and pass the write_buffer function pointer so that it doesn't write to a file but instead it will call my function with the required data

  


  unsigned char * aviobuffer = (unsigned char *) av_malloc (32768);
AVIOContext * avio = avio_alloc_context (aviobuffer, 32768,1, NULL, NULL, write_buffer, NULL);

AVFormatContext* containerContext;
avformat_alloc_output_context2(&containerContext, NULL, "s16le", NULL);
containerContext->pb = avio;


  


  here is my write_buffer function

  


  std::vector<char>* data;&#xA;int write_buffer(void *opaque, uint8_t *buf, int buf_size)&#xA;{&#xA;    std::vector<char> tmp;&#xA;    tmp.assign(buf, buf &#x2B; buf_size);&#xA;    data->insert(data->end(), tmp.begin(), tmp.end());&#xA;    return buf_size;&#xA;}&#xA;</char></char>

  


  now when i call avformat_write_header() it doesn't call my write_buffer() function + it returns 0 which means success.

  


  int ret = avformat_write_header(containerContext, NULL);


  


  after that i call the appropriate functions to get the data body itself and my write_buffer() get called normally so i am now left with the data body with no header !!

  


  how can i get the output header anyways ?

  


• FFmpeg doesn't work in Rails 3 app with Apache and Passenger in GoDaddy CentOS

  29 décembre 2011, par pablo89

  I try to upload a .mp4 video file, and it works ; I made a Bash script that calls ffmpeg in order to get the thumbs of the video. It works fine in localhost, but when I uploaded the project to a dedicated server in GoDaddy with CentOS it doesn't work, it doesn't create the thumbnails, and it shows no error. The Rails App is running under Apache with Passenger. I have tried everything, even I gave 0777 permissions to the action and to the Bash script, but nothing, it doesn't show any error, but it doesn't work.

  This is the action in Rails (as you can see, I use the commands system and exec) :

  def create
  
    if !params[:video][:video].nil?
  
      videoName = params[:video][:video].original_filename.gsub(/\s/,'_') 
  
      @video = Video.new({:title => params[:video][:title], :video => "/worshipvideos/#{videoName}"})
  
    else
  
      @video = Video.new({:title => params[:video][:title]})
  
    end
  
  
  
    if !params[:video][:video].nil?
  
      tmp = params[:video][:video].tempfile
  
      file = File.join("public/worshipvideos", videoName)
  
      FileUtils.cp tmp.path, file
  
      FileUtils.rm tmp
  
    end
  
  
  
    respond_to do |format|
  
      if @video.save
  
        if !params[:video][:video].nil?
  
          logger.debug "./createVideoPics.sh '#{videoName}'"
  
          fork do
  
            system("./createVideoPics.sh '#{videoName}'")
  
            #exec("./createVideoPics.sh '#{videoName}'")
  
          end
  
  
  
          @video.update_attribute("pic1", "worship_pics/#{videoName}_1.jpg")
  
          @video.update_attribute("pic2", "worship_pics/#{videoName}_2.jpg")
  
          @video.update_attribute("pic3", "worship_pics/#{videoName}_3.jpg")
  
        end
  
  
  
        format.html { redirect_to @video, notice: 'Video was successfully created.' }
  
        format.json { render json: @video, status: :created, location: @video }
  
      else
  
        format.html { render action: "new" }
  
        format.json { render json: @video.errors, status: :unprocessable_entity }
  
      end
  
    end
  
  end

  This is the script in Bash :

  #!/bin/bash
  
  chmod 0777 "public/worshipvideos/$1"
  
  ffmpeg -i "public/worshipvideos/$1" -an -ss 00:00:20 -r 1 -vframes 1 -f mjpeg -y "app/assets/images/worship_pics/${1}_1.jpg"
  
  ffmpeg -i "public/worshipvideos/$1" -an -ss 00:00:40 -r 1 -vframes 1 -f mjpeg -y "app/assets/images/worship_pics/${1}_2.jpg"
  
  ffmpeg -i "public/worshipvideos/$1" -an -ss 00:01:00 -r 1 -vframes 1 -f mjpeg -y "app/assets/images/worship_pics/${1}_3.jpg"
  
  echo "End of making thumbs"

  If I try to make the command in terminal ./createVideoPics.sh "abc.mp4" it works, it makes the thumbs ; it only doesn't work inside the Rails App.

  What do you think would be the problem ? thanks in advance

• Streaming to localhost using FFmpeg doesn't work

  16 février 2023, par jostanise

  I'm trying to stream my screen using FFmpeg, but I can't access it using VLC player - it keeps loading the stream and doesn't show anything.

  


  The command I use :

  


  ffmpeg -f gdigrab -s 1920x1080 -i desktop -preset ultrafast -vcodec libx264 -tune zerolatency -b 900k -f rtp rtp://localhost:1234


  


  The network URL I put in VLC :

  


  udp://localhost:1234


  


  What am I doing wrong ?