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• ffmpeg command for overlaying a video onto am image with blend

  6 décembre 2022, par tebowner

  I have these requirements but cant seem to get this even close :

  


  

  • ffmpeg to produce a mp4 video

  


  • inputs : an image of varying size, an audio wav of X length, a video for the overlay such as particles or dust

  


  • create an mp4 with the image as the final video size, the overlay video light blended into the image using zoom/crop (no stretching of size), length of video is size of audio

  


  • assume the video overlay is bigger than the image as far as height and width

  


  


• Debugging Gstreamer pipeline with tee and a filesink in C

  28 septembre 2020, par NicolasBourbaki

  There is an excellent example on how to construct a C program using GStreamer and its tee and filesink elements on https://gist.github.com/crearo/a49a8805857f1237c401be14ba6d3b03.
(Another one can be found on https://gstreamer.freedesktop.org/documentation/tutorials/basic/multithreading-and-pad-availability.html?gi-language=c).

  


  The idea of the tee element in a pipeline is similar like the tee program in Unix : Like a T-shaped tube, it allows to add a bifurcation to a pipeline, which is in my case used to display a video stream to the screen (which works perfectly) and writing it at the same time to a file (which doesn't work - the file is created but stays empty, i.e. has a size of 0 bytes after closing the program).

  


  I deviated from the examples mentioned above by neither having a queue element for recording (because I also don't have one for displaying, which works) as well as neither having an encoder nor a muxer. Although this might be a problem for what gets written to the file in the end, I would expect that there is written something to the file at all.

  


  The program does compile. What additional diagnostics could I run in order to pin down the problem ?

  


• Unwrap mp4 from flv video

  16 mai 2012, par Matt C

  I used ffmpeg to wrap an mp4 (h264) file in an flv container. I need to do this to inject metadata into the flv for pseudostreaming to Flash players.

  My question, once the wrapped flv file is on my server, is there a way to output the mp4 file to a browser using PHP ? That way I can just have the one flv file, but send it as an mp4 to mobile devices and as an flv to Flash capable devices ?

  From what I understand the mp4 was not re-encoded, but just given a flv header. I am hoping there is a way to get the mp4 data and spit it out on the fly.