Recherche avancée

Sur d’autres sites (8128)

• Video playing, how to play a video back a a rapid rate at random timestamp locations

  10 avril 2020, par Zarc Rowden

  Note : this is a mildly general question that is looking more for pointers in the right direction and not exactly requiring a concise coded answer. I appreciate any and all input, thank you for lending your brain power to me for this moment :)

  



  I have a script that receives midi messages in real time and triggers playback of a single video on various timestamps that are changed/selected regularly and randomly by a user. Currently this is working in the browser, however, I've realized that there is some noticeable latency between (i'm guessing the cause here so please correct me) the moment a request to play a video at a specific time is made(note : the video is not being requested over the wire, this action does not take place until a JS Blob Url is loaded into the player) and the moment where that request is fulfilled and delivered from storage to pixels on the screen.

  



  My question is : Is it reasonable to assume that there is a tool out there, that given the correct video format and optimizations both in the code and in the file that could load an entire, say : 1 gb video into memory and play it back at random timestamps every 60 milliseconds at completely random, constantly changing timestamps.

  



  If you're now all the way down here... Thanks for reading this far, or scanning ! Please let me know if this question makes any sense / could be improved, I'm happy to clarify further.

  


• Use ffmpeg Windows batch script on OS X

  3 novembre 2015, par andisk

  I got an ffmpeg batch script written by someone. The script takes all video clips of a specific folder, cuts off first and last frame, converts the clips to ProRes and saves them in a new folder. I got it running under Windows (just have to double-click the *.bat file and it does what it’s supposed to do).
  But now I need that same script running on a mac. I’ve installed ffmpeg over homebrew. Then I tried to make a Automator-Service, but with no success. Best thing would be if I could just right click on the folder with the videos, go to services and click on convert. I’m not really into coding and scripting, but the people who should use the script are happy when they find the power switch of the computer..
  Can anyone help me with this ?
  Cheers andisk

  Edit : Here’s the code

      `@echo off
  
  
  
  
  
      mkdir tmp
  
      mkdir converted
  
  
  
  
  
      set pathtofind=%~dp0
  
      echo Searching for files in %pathtofind%%1\
  
  
  
  
  
      setlocal enableextensions
  
      setlocal ENABLEDELAYEDEXPANSION
  
  
  
  
  
  
  
      for %%f in (%pathtofind%%1\*) do (
  
              echo Handling file %%f
  
              ffmpeg -y -loglevel quiet -i %%f tmp\%%d.png
  
              set count=0
  
              for %%x in (tmp\*) do set /a count +=1
  
              echo Deleting frames 1 and !count!
  
              del tmp\1.png
  
              del tmp\!count!.png
  
              echo Saving %%~nf.mov
  
              ffmpeg -y -loglevel verbose -f image2 -r 24 -i tmp\%%d.png -vcodec prores -profile:v 1 -r 24 converted\%%~nf.mov
  
              del /q tmp\*.*
  
  
  
              echo ---------------------------
  
      )
  
  
  
  
  
      rd tmp`

• Video processing to support different web players and qualities [closed]

  15 mai 2013, par Linas

  I am trying to accomplish something similar to youtube player.

  The biggest issues I'm facing now is how should I process user uploaded video file.

  For example since i want to switch between 240p, 360p, 480p and 720p I need to convert uploaded video file to 4 different files for each resolution, and because not all browsers can play mp4 i need ogg, mp4, webm, so that makes 12 video files, and say if it takes 10 minutes to process 1h video file it would take me about 2h just to process that file which is insane. I know that youtube is ussing cloud servers to process each video file and they have a lot of processing power but I think there some kind of trick to this.

  So my question is what can i do about this, and how does youtube deal with this ?

  My second question is ffmpeg suited for this kind of work, and if so why does this command takes pretty much for ever to finish, I ran this command on a 720p 3minutes long video file and after 15minutes of processing I just canceled the process.

  ffmpeg -i hd.webm a.mp4

  This one on the other hand took about 7 minutes to finish but it generated 200mb video file out of 25mb file

  ffmpeg -i hd.webm -c:v libx264 -preset ultrafast a.mp4