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• Is it possible to merge two or more videos in real-time like this ?

  25 février 2015, par Marko

  Is it possible to play video online that’s made of two or more video files ?

  Since my original post wasn’t clear enough, here’s expanded explanation and question.

  My site is hosted on Linux/Apache/PHP server. I have video files in FLV/F4V format. I can also convert them to other available formats if necessary. All videos have same aspect ratio and other parameters.

  What I want is to build (or use if exist) online video player that plays video composed of multiple video files concatenated together in real-time, i.e. when user clicks to see a video.

  For example, visitor comes to my site and sees video titled "Welcome" available to play. When he/she clicks to play that video, I take video files "Opening.f4v", "Welcome.f4v" and "Ending.f4v" and join/merge/concatenate them one after another to create one continuous video on the fly.

  Resulting video looks like one video, with no visual clues, lags or even smallest observable delay between video parts. Basically what is done is some form of on-the-fly editing or pre-editing, and user sees the result. This resulting video is not saved on the server, it’s just composed and played that way real-time.

  Also, if possible, user shouldn’t be made to wait for this merging to be over before he/she sees resulting video, but to be able to get first part of the video playing immediately, while merging is done simultaneously.

  Is this possible with flash/actionscript, ffmpeg, html5 or some other online technology ? I don’t need explanation how it’s possible, just a nod that it’s possible and some links to further investigate.

  Also, if one option is to use flash, what are alternatives for making this work when site is visited from iphone/ipad ?

• FFMPEG Generate video clips and concatenate them all

  8 février 2020, par lms702

  I have a bunch of images (.png) and audio files (.wav) that I want to combine and concatenate. For example, if I have a1.wav, i1.png, a2.wav, and i2.png, I want to output a video that is a1.wav overlayed onto i1.png, then (concatenated to a2.wav overlayed onto i2.png.

  Currently, my approach is to save each individual clip and then concatenate them all at the end.

  To save each clip, I use this command (in a loop for all of my clips) :

  ffmpeg -i {imageFile} -i {audioFile} -nostdin -qscale:v 1 -vcodec libx264 -pix_fmt yuv420p {outputFile.mp4}``

  It outputs an mp4 that kind of works - the playback is really buggy but works in full screen.

  My current approach to concatenating has not been at all successful. I create a list of the clip names and put it into filename then call this command :

  ffmpeg -f concat -i {filename} -c copy clips/finalOutput.mp4

  This outputs a pretty jumbled video and this error repeated :

  [mp4 @ 000001cdec110740] Non-monotonous DTS in output stream 0:1; previous: 1045041, current: 604571; changing to 1045042. This may result in incorrect timestamps in the output file.

  So, a few questions.

  What is the best way to go about this process ?

  Should I be saving each clip or is there a better way to do it all in one command ?

  If I do save each clip, is there a better file format I should use ?

  Plz help with the concatenation command.

  Also note that because I am automating this with python I can build arbitrarily large commands, though that might not be ideal.

  I am very new to this and I would really appreciate any help !

• vp9 : split superframes in the filtering stage before actual decoding

  13 novembre 2016, par Anton Khirnov

  vp9 : split superframes in the filtering stage before actual decoding
  Significantly increases the efficiency of frame threading, since
  
  individual frames in a superframe can now be decoded in parallel.
  

  • [DBH] configure
  • [DBH] libavcodec/vp9.c