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• Opencv 3.1 compiled with FFMPEG, but won't open https urls

  2 mars 2018, par stalagmite7

  I work on a 16.04 system, and have successfully installed opencv 3.1 with FFMPEG flags enabled. I double checked this was actually the case by cv2.getBuildInformation() and I got FFMPEG = YES.

  I am trying to open a video that is hostel on a private server by my workplace (I am logged in to the VPN, in case thats a concern) and I can access this video over the browser. But videocapture with cv2 fails.

  >>> cap = cv2.VideoCapture("https://xxx.mp4", cv2.CAP_ANY) #dummy url
  
  >>> cap
  
  <videocapture 0x7f63300fa4b0="0x7f63300fa4b0">
  
  >>> cap.isOpened()
  
  False
  
  </videocapture>

  This is always the case for https urls. It seems to be able to work with local videos just fine. I have tried a bunch of different thing : initially thought it was a gstreamer problem so I checked my plugins, had some gst-bad versions (ref : https://github.com/GStreamer/gst-plugins-ugly), removed those and replaced with good versions, no joy. Also tried to explicitly tell videoCapture to use cv2.CAP_ANY and cv2.CAP_FFMPEG flags while reading the video, still no luck.

  I disabled the Gstreamer flag while compiling opencv, but even with it set to ON, there was no difference in my problem.

  I haven’t been able to find a solution to this issue and have been looking and trying different things for days now ! Any ideas ?

• Can ffmpeg seek when using an input stream (or url) ?

  17 janvier 2016, par Roee

  I’ve been using ffmpeg quite a lot in the past few weeks, and recently I’ve encountered a very annoying issue - when I use ffmpeg with an input stream (usually, just a url as the input) and try to set a start time (with -ss option), I always get a warn message that says "could not seek to position : XXX".

  Then, ffmpeg just starts to download the file, and it ouputs nothing until it has downloaded enough data and got to my desired start time.

  I’ll give an example :

  I use this command to execute ffmpeg :

  ffmpeg -ss 50 -re -i https://ascent.usbank.com/acp/videos/041114ascent.flv -b:a 128k -ac 2 -acodec libvorbis -b:v 1024k -vcodec libtheora -strict 2 -preset ultrafast -tune zerolatency -pix_fmt yuv420p -f ogg pipe:1

  and I get the warn message

  https://ascent.usbank.com/acp/videos/041114ascent.flv: could not seek to position 50.000

  Then, it takes about 30 seconds until ffmpeg starts to output data to stdout. And when I try this with longer videos (and longer seek times), it takes even longer.

  My question is, what can I do ? I guess it’s impossible for ffmpeg to seek when it haven’t got the whole input stream... Am I wrong ? Or is there any other solution ?

  Of course I try to avoid downloading the entire file from the web...

  Thanks in advance !

  Roee.

• Can ffmpeg seek when using an input stream (or url) ?

  27 juin 2022, par Roee

  I've been using ffmpeg quite a lot in the past few weeks, and recently I've encountered a very annoying issue - when I use ffmpeg with an input stream (usually, just a url as the input) and try to set a start time (with -ss option), I always get a warn message that says "could not seek to position : XXX".

  



  Then, ffmpeg just starts to download the file, and it ouputs nothing until it has downloaded enough data and got to my desired start time.

  



  I'll give an example :

  



  I use this command to execute ffmpeg :

  



  ffmpeg -ss 50 -re -i https://ascent.usbank.com/acp/videos/041114ascent.flv -b:a 128k -ac 2 -acodec libvorbis -b:v 1024k -vcodec libtheora -strict 2 -preset ultrafast -tune zerolatency -pix_fmt yuv420p -f ogg pipe:1


  



  and I get the warn message

  



  https://ascent.usbank.com/acp/videos/041114ascent.flv: could not seek to position 50.000


  



  Then, it takes about 30 seconds until ffmpeg starts to output data to stdout. And when I try this with longer videos (and longer seek times), it takes even longer.

  



  My question is, what can I do ? I guess it's impossible for ffmpeg to seek when it haven't got the whole input stream... Am I wrong ? Or is there any other solution ?

  



  Of course I try to avoid downloading the entire file from the web...

  



  Thanks in advance !

  



  Roee.