Advanced search

On other websites (12572)

• converting png to movies with R via ffmpeg

  10 May 2021, by user237554

  I want to convert a series of *.png files to a movie with R and have installed ffmpeg in the root directory. I think the installation has been successful because if I type

  


       ffmpeg -version


  


  in terminal I get all of the version information etc., etc.

  


  I have my *.png files saved in the wd and in R I say

  


      imgs <- list.files(pattern="*.png")
        saveVideo({
        for(img in imgs){
          im <- magick::image_read(img)
          plot(as.raster(im))
        }
      })


  


  I get an error message that "the command ""ffmpeg"" is not available in your system. Please install FFmpeg". Is there something I need to do to get R and ffmpeg to talk to each other? Again, from terminal, ffmpeg is in the directory and it looks like it installed.

  


  thanks

  


• Is "begin" param dead in Youtube's *.c.youtube.com/videoplayback?

  23 January 2013, by Minime

  I tested Youtube video download with begin param using ytdl, and realized that it's not working properly. Below is an URL with begin param. (It won't work on your side because it's session-IP address based.)

  http://r4---sn-o097znee.c.youtube.com/videoplayback?ratebypass=yes&cp=U0hUTVNOT19JTENONF9LSFNIOmtjaWozaFd5Vnhl&newshard=yes&source=youtube&ipbits=8&fexp=916600%2C906072%2C923114%2C914093%2C916626%2C920704%2C912806%2C922403%2C922405%2C929901%2C913605%2C925710%2C929104%2C929110%2C908493%2C920201%2C913302%2C919009%2C911116%2C926403%2C910221%2C901451&id=58dafac107cd7cae&key=yt1&mt=1358307193&gcr=us&ms=au&itag=46&upn=efQT2cDue5M&ip=xxxx&sparams=cp%2Cgcr%2Cid%2Cip%2Cipbits%2Citag%2Cratebypass%2Csource%2Cupn%2Cexpire&expire=1358331742&sver=3&mv=m&signature=C957313FEC2AC174F72CEFE52BF663ABAC8D0E4B.27F8485A36BE654CA25D3CA75A927D443523CA68&begin=12000

  I traced Youtube site by myself to see if there are any recent changes on their black boxed
  API. And I found that begin param is no longer put in videoplayback, but put in user_watch as below.

  http://www.youtube.com/user_watch?video_id=-YFiHW59ASs&ptk=StyleHaul&referrer=None&t=vjVQa1PpcFPiDK6v9s-rWrDn8gNv0QvpjyCIjiAgsm0=&asv=3&fmt=34&cpn=BOOMP-Bzbv1jikj9&el=detailpage&plid=AATTaqGSIR9CQ-MJ&begin=70000

  Its response is

  <?xml version="1.0" encoding="utf-8"?>

  And videoplayback only has range param, which indicate byte range where to pull. However, I couldn't figure out exact mechanism how new begin param works.

  http://r8---sn-p5q7yne6.c.youtube.com/videoplayback?algorithm=throttle-factor&burst=40&cp=U0hUTVNSVl9IT0NONF9LTFpGOlY5MU5RYVYtWHFw&cpn=BOOMP-Bzbv1jikj9&expire=1358378535&factor=1.25&fexp=919361%2C910207%2C916612%2C913112%2C912806%2C922403%2C922405%2C929901%2C913605%2C925710%2C929104%2C929110%2C908493%2C920201%2C913302%2C919009%2C911116%2C910221%2C901451&gcr=us&id=f981621d6e7d012b&ip=xxxx&ipbits=8&itag=34&keepalive=yes&key=yt1&ms=au&mt=1358354777&mv=m&newshard=yes&ratebypass=yes&signature=AA38C7074D8FA9DA44D01D9BB3675C78D05B9794.66D67C5AB111D8FB9EC3C8A141BBB11D9D70545D&source=youtube&sparams=algorithm%2Cburst%2Ccp%2Cfactor%2Cgcr%2Cid%2Cip%2Cipbits%2Citag%2Csource%2Cupn%2Cexpire&sver=3&upn=aLby9GtO0sU&range=3563520-5345279

  Can anyone explain how to pull a video starting from specific position(msec) in new API?

• How to mix images and movies with ffmpeg

  30 July 2014, by Catalin

  I have a bunch if h264 encoded mp4 files (of about 10-15 seconds) and I want to mix them with another bunch of jpegs (which should be displayed for x seconds each).
  So I’ve setup the concat.txt file :

  file slide_1.jpg
  
  duration 3
  
  file movie_1.mp4
  
  file slide_2.jpg
  
  duration 5
  
  file movie_2.mp4

  and I am trying to run

  yes | scripts/ffmpeg -f concat -i concat.txt -vcodec copy -c:a copy final.mp4

  which generates a movie with the length of 6 hours (6:48:34) and in which I can only see the 1st picture.

  How do I fix this ?