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• JW Player fails with error with wma files : Task Queue failed at step 5

  17 mars 2018, par Sabeena

  I have a JW Player which plays MP3 files but with WMA files it gives the error :

  Task Queue failed at step 5: Playlist could not be loaded: Playlist file did not contain a valid playlist

  I thought of two reasons :

  1. There is no support for WMA but please confirm me this.
  2. Somewhere I need to setup the type of file I am using in this player.

  If WMA not supported in JW Player how can I play WMA and MP3 files in my website ?

  Is ffmpeg needed to convert WMA to MP3 while uploading ?

• How can I correctly provide a mock webcam video to Chrome ?

  15 décembre 2022, par doppelgreener

  I'm trying to run end-to-end testing in Chrome for a product that requires a webcam feed halfway through to operate. From what I understand this means providing a fake webcam video to Chrome using the --use-file-for-fake-video-capture="/path/to/video.y4m" command line argument. It will then use that as a webcam video.

  



  However, no matter what y4m file I provide, I get the following error from Chrome running under these conditions :

  



  DOMException: Could not start video source
{
  code: 0,
  message: "Could not start video source",
  name: "NotReadableError"
}


  



  Notably I can provide an audio file just fine using --use-file-for-fake-audio-capture and Chrome will work with it well. The video has been my sticking point.

  



  This error comes out of the following straightforward mediaDevices request :

  



  navigator.mediaDevices.getUserMedia({ video: true, audio: true })
  .then(data => {
    // do stuff
  })
  .catch(err => {
    // oh no!
  });


  



  (This always hits the “oh no !” branch when a video file is provided.)

  



  What I've tried so far

  



  I've been running Chrome with the following command line arguments (newlines added for readability), and I'm using a Mac hence the open command :

  





  open -a "Google Chrome" --args
  --disable-gpu
  --use-fake-device-for-media-stream
  --use-file-for-fake-video-capture="~/Documents/mock/webcam.y4m"
  --use-file-for-fake-audio-capture="~/Documents/mock/microphone.wav"


  



  webcam.y4m and microphone.wav were generated from a video file I recorded.

  



  I first recorded a twenty-second mp4 video using my browser's MediaRecorder, downloaded the result, and converted it using the following command line commands :

  



  ffmpeg -y -i original.mp4 -f wav -vn microphone.wav
ffmpeg -y -i original.mp4 webcam.y4m


  



  When this didn't work, I tried the same using a twenty-second movie file I recorded in Quicktime :

  



  ffmpeg -y -i original.mov -f wav -vn microphone.wav
ffmpeg -y -i original.mov webcam.y4m


  



  When that also failed, I went straight to the Chromium file that explains fake video capture, went to the example y4m file list it provided, and downloaded the grandma file and provided that as a command line argument to Chrome instead :

  



  open -a "Google Chrome" --args
  --disable-gpu
  --use-fake-device-for-media-stream
  --use-file-for-fake-video-capture="~/Documents/mock/grandma_qcif.y4m"
  --use-file-for-fake-audio-capture="~/Documents/mock/microphone.wav"


  



  Chrome provides me with the exact same error in all of these situations.

  



  The only time Chrome doesn't error out with that mediaDevices request is when I omit the video completely :

  



  open -a "Google Chrome" --args
  --disable-gpu
  --use-fake-device-for-media-stream
  --use-file-for-fake-audio-capture="~/Documents/mock/microphone.wav"


  



  Accounting for C420mpeg2

  



  TestRTC suggests Chrome will “crash” if I give it a C420mpeg2 file, and recommends that simply replacing the metadata fixes the issue. Indeed the video file I generate from ffmpeg gives me the following header :

  



  YUV4MPEG2 W1280 H720 F30:1 Ip A1:1 C420mpeg2 XYSCSS=420MPEG2


  



  Chrome doesn't actually crash when run with this file, I just get the error above. If I edit the video file to the following header though per TestRTC's recommendations I get the same situation :

  



  YUV4MPEG2 W1280 H720 F30:1 Ip A1:1 C420 XYSCSS=420MPEG2


  



  The video file still gives me the above error in these conditions.

  



  What can/should I do ?

  



  How should I be providing a video file to Chrome for this command line argument ?

  



  How should I be recording or creating the video file ?

  



  How should I convert it to y4m ?

  


• OpenCV won't open some videos of many videos of the same format

  2 octobre 2013, par OpenMinded

  I am using Visual Studio 2012 with OpenCV 2.4.6.

  I have 4 videos that I recorded one by one with my Nokia Lumia 920. OpenCV won't open .mp4 format from my phone by the default. So I converted all these 4 videos using Sony Vegas to .mp4 with the SAME preferences for all of them. Now the problem is that OpenCV has a problem to open two of them. The other two works like a charm with no problem. Below is the information about codec that I used (Yes, it is the same for all videos) :

  

  And this is the error :

  

  Why is it so that they are the same type but only a few of them are loaded properly ?