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• FFMPEG h.264 stream to VLC from raw YUV444 produces black screen

  30 novembre 2018, par GerbGerb

  Not sure if this fits better here or over on Super User, so please redirect if here is the wrong place.

  I am piping raw YUV444 640x480 frames to ffmpeg from inside a C++ program using stdout. ffmpeg encodes them using h.264 and streams the video via UDP to an IP of my choice.

  When I am not streaming and saving the video as -mp4 file, everything works - But when I stream over the network and try to receive in VLC, the stream is received and the playing timer under the video screen runs, but the image is black, none of the video is displayed. Also I have some crackling sounds on my audio output.

  My FFMPEG settings are as follows :

  ffmpeg -y -loglevel info -f rawvideo -r 25 -c:v rawvideo -pix_fmt yuv444p -s 640x480 -i - -c:v libx264 -preset superfast -framerate 25 -f mpegts udp://192.168.150.1:20001

  in VLC, I just use "open network stream" with udp ://@:20001. The port is open, I tested it with a simple dummy sender/receiver.
  Almost the same cli arguments for the video recording lead to a perfectly playable video when writing to a file and downloading it :

  ffmpeg -y -loglevel info -f rawvideo -r 25 -c:v rawvideo -pix_fmt yuv444p -s 640x480 -i - -c:v libx264 -preset superfast -framerate 25 video.mp4

  If I try to stream the same video using

  ffmpeg -i video.mp4 -v 0 -vcodec mpeg4 -f mpegts udp://192.168.150:20001

  the screen remains black.

  VLC debug output changes between different runs, because other modules are selected, so I assume stream type recognition goes haywire. But why ?

  What am I doing wrong ?

  Here the ffmpeg log
  and the VLC log

• ffmediaplayer playing but screen keeps black

  27 août 2023, par Joergahmann

  I#m coding a video tool for sports with the Windows Template Studio and using the Community Toolkit.MVVM. I finished this with the vlcMediaPlayer and it worked almost fine. I need the Frameback (vlc does not provide) and I like autohiding the controls (which is hard with vlc). So I decided to use the ffmediaelemrnt instead.
Almost everything is ok (I hear sound, i can pause, forward ..), only the Video is not showing !!

  


  I'm using an observable property

  


  `    [ObservableProperty]
     private MediaElement _ffmeMediaElement;`


  


  instead of the original implementation with a complete different basemodel :

  


  public MediaElement MediaElement
        {
            get
            {
                if (m_MediaElement == null)
                    m_MediaElement = (Application.Current.MainWindow as MainWindow)?.Media;

                return m_MediaElement;
            }
        }


  


  —> Could this be the problem ? How do I get the (Application.Current.MainWindow as MainWindow) ? in my case with no mainwindow and a page instead


  


                      



  


  What I tried
When I use a contentcontrol instead : the Video is showing, but the controls are not autohiding anymore

  


  When I compile your WindowsSample, it works completly, but still shows the error Object reference not set to an instance of an object on

  


  I would appreciate any help. Thank you in advance

  


• ffmpeg : real time buffer full frame dropped

  10 mai 2015, par Nyaruko

  I am using ffmpeg to write a simple program to read the webcam.
  However, in some case I get the printing said :

  real time buffer 80% full frame dropped

  But the program still keeps running.
  I’ve checked the internet and the reason is due to the limited buffer size.
  My question is : will this cause any problems ? should I write code to deal with it ?
  For my application, I am just viewing the frames and loss some frames are totally fine.