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• How to extract a video snippet from a video file that is being written in by ffmpeg in realtime

  26 février 2015, par alex.b

  At the moment i am recording a LIVE stream video from youtube with youtube-dl (https://github.com/rg3/youtube-dl)

  The command i use for this :

  youtube-dl --id -f 92 https://www.youtube.com/watch?v=VYlQJbsVs48

  92 is a format code that i got after executing a command to get the formats, that gave me this list :

  format code  extension  resolution note
  
  140          m4a        audio only DASH audio  144k , m4a_dash container, aac  @128k (48000Hz)
  
  141          m4a        audio only DASH audio  272k , m4a_dash container, aac  @256k (48000Hz)
  
  160          mp4        256x144    DASH video  124k , 15fps, video only
  
  133          mp4        426x240    DASH video  258k , 30fps, video only
  
  134          mp4        640x360    DASH video  616k , 30fps, video only
  
  135          mp4        854x480    DASH video 1116k , 30fps, video only
  
  136          mp4        1280x720   DASH video 2216k , 30fps, video only
  
  137          mp4        1920x1080  DASH video 4141k , 30fps, video only
  
  151          mp4        72p        HLS
  
  132          mp4        240p       HLS
  
  92           mp4        240p       HLS
  
  93           mp4        360p       HLS
  
  94           mp4        480p       HLS
  
  95           mp4        720p       HLS
  
  96           mp4        1080p      HLS  (best)

  This is creating a file called VYlQJbsVs48.mp4.part that gets bigger and bigger of course.

  Is there a way to extract a video snippet from that live stream or form the part file ? Or maybe there is a better way of doing this ?

  What i have noticed is that if i force quit iTerm2 while youtube-dl is running the .part file it creates wont contain any index information (something to do with an moov atom not being present in the mp4 file - which is the information about the number of frames and other things - metadata i think), so it makes me think i cannot extract from the file.

  Maybe if there would be a way that youtube-dl can write the index information at all times or maybe another way that i can record the live stream and get video snippets while its recording.

  I forgot to mention i am doing this on OSX Yosemite. I have FFMPEG installed with homebrew and youtoube-dl

  I am more than happy to try stuff on UBUNTU if there is a solution.

  Any help would be greatly appreciated.

  Thank you.

  Alex

• FFMPEG Overlay video on top of another video

  19 mai 2014, par James Blackbj Blackburn

  I have looked through all the questions on this on stackoverflow but none of the answers worked for me.

  I have a screen recorded video in mp4 and another video recorded from a webcam in mp4. I want to overlay the webcam video over the top left of the screen recorded video.

  I think I finally found the right command line for doing this but when I step through the ffmpeg process it freezes when it reaches " handler_name :SoundHandler".

  Here is my command line :

  string overlayPosition = "movie=" + '"' + _videoFile.FileName + '"' + "[inner]; [in][inner] overlay [out]";
  
  string overLayCommand = "-i " + '"' + videoList[0].Path + '"' + " -vf " + '"' + overlayPosition + '"' +  + '"' + " C:\\Users\\james\\output.mp4" + '"';

  Does anyone know what I am doing wrong ? I’ve managed to trim audio and video, crop video, join sound, join video, and join sound and video but cannot get overlay to work :(.

• When NVIDIA GPU is used for H265 video decoding acceleration, the video screen may skip forward frames, while AMD GPU does not [closed]

  16 août 2023, par uproar

  We are using NVIDIA GPUs (model : GTX1050TI) to accelerate H.265 video decoding and rendering, and DXVA2 hardware acceleration is used. The version of FFmpeg is 4.2.2.
If the video is played for a long time, there will be frame skipping forward (that is, the video frame of the first few seconds will appear when it is played in normal order), and it will always exist after it appears, and it will not heal itself.
Has anyone been in the same situation or can anyone help ?

  


  We checked the rendering and playback timing of each frame and found that no forward jump occurred. Therefore, the data decoded by the GPU may be incorrect.
We also used AMD GPUs for comparison tests, but this is not the case with AMD GPUs.