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• 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.

• 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 ffprobe consume piped ffmpeg output ?

  19 mai 2020, par slifty

  The Situation

  



  I'm writing a NodeJS script that takes a video stream (or file), pipes it to ffmpeg to standardize the format, and then sends it to various ETL processes to extract data from the video.

  



  I want my node-level data stream to have awareness of how far into the video it is, and it seems the best (only ?) way to do this is to use ffprobe to extract times from the stream packets.

  



  The Problem

  



  Before I actually start spawning ffmpeg commands, I'm trying to test at the CLI level. When I pipe ffmpeg's output directly to ffprobe, I receive a complaint :

  



  av_interleaved_write_frame(): Broken pipe
Error writing trailer of pipe:: Broken pipe


  



  The command in question :

  



  ffmpeg -i /path/to/in.mp4 -f mpegts - | ffprobe -i - -print_format json


  



  The Question

  



  Am I misunderstanding something about what ffprobe accepts ? I haven't found a single example of ffmpeg piping to ffprobe, which makes me nervous.

  



  Is it possible to pipe ffmpeg data directly to ffprobe ?

  



  Bonus points : if you have a better way of extracting timing information from the ffmpeg stream, take a look at this question