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• time progress bar does not scale by sec in FFMPEG chopped mp4 in iOS and Android devices

  10 juillet 2017, par Xi Xiao

  I have used the below command to cut out a 44sec length video. The result video can be found here.

  ffmpeg -i friends.mkv -ss 00:15:30.0 -t 44 -vf scale=640:360  video.mp4

  One odd issue appears from the generated video.mp4.

  when playing it in iphone 7 and huawei honor8 android, the time progress bar does not scale by second.

  What I mean is, for example, the video can start to play either from 0 second or 6 second. But, if I drag the progress bar to time between 0 - 6, such as 4, the video player will jump to 0 and play, instead of playing from 4 second.

  When I use Javascript to setTime for 2 second for html5 video player, it does not work either, i.e. the player will play from 0 second instead of 2. Code is as below :

  var vid = document.getElementById("video1");
  
  vid.currentTime = 2;
  
  vid.play();

  screenshot made in iphone 7

  I stop the video, try set the progress bar between 0 and 6 as in screenshot. When I click play, the player will play from 0.

  

  In what devices have I tested it ?

  • This issue appears in iphone 7, huawei honor8 android phone.
  • This issue does not appear in PC browser, nor in ipad.

  At last, I suspect that the issue roots from video codec, but had no success to locate the keyword to explain my issue and google the solution.

• Reading geolocation data from a video file using FFMpeg/Xuggler

  23 décembre 2015, par agent154

  Using the MediaInfo application, I am able to see that a file taken with an iPhone 5 contains geolocation metadata, tagged both with ©xyz and com.apple.quicktime.location.ISO6709. I am not able to find any way to get this data using xuggler, however.

  Format                                   : MPEG-4
  
  Format profile                           : QuickTime
  
  Codec ID                                 : qt   0000.00 (qt  )
  
  File size                                : 7.50 MiB
  
  Duration                                 : 3s 537ms
  
  Overall bit rate                         : 17.8 Mbps
  
  Recorded date                            : 2015-12-17T14:32:23-0330
  
  Encoded date                             : UTC 2015-12-17 18:02:23
  
  Tagged date                              : UTC 2015-12-17 18:02:27
  
  Writing application                      : 8.4.1
  
  Writing library                          : Apple QuickTime
  
  Model                                    : iPhone 5
  
  ©xyz                                     : +47.5184-052.8046+133.390/
  
  Make                                     : Apple
  
  com.apple.quicktime.make                 : Apple
  
  com.apple.quicktime.creationdate         : 2015-12-17T14:32:23-0330
  
  com.apple.quicktime.location.ISO6709     : +47.5184-052.8046+133.390/
  
  com.apple.quicktime.software             : 8.4.1
  
  com.apple.quicktime.model                : iPhone 5

  As an aside, there seems to be a lot of metadata on this file that I can’t immediately find while debugging via xuggler.

  The question at Reading Geolocation from Quicktime Movies with Java (Xuggler) ? is asking the exact same question, but has no answers or comments at all, and is over 4 years old.

  Is anybody aware of a way to be able to get this data using xuggler as it is, or how I can modify the source and re-compile to make it work ? I am required to get this data for a work project. Thanks.

• Connect external cameras to iOS and decompress to a usable form

  27 septembre 2017, par Ping Chen

  I want to create a 2 camera setup which can send 1 of the camera views out as an RTMP stream depending on the motion intensity detected. The chosen camera view can change if motion intensity on the views changes.

  I imagine that I could use an iPhone/iPad as encoding/streaming hub as well as 1 of the cameras. And connect a WiFi camera to the iPad/iPhone to feed the 2nd camera view.

  My goals for the iOS side are :

  1. Connect with a WiFi camera on the local network
  2. Decode the data and run motion intensity detection on the WiFi camera feed AND the iPhone/iPad’s own camera feed with Brad Larson’s GPUImage framework https://github.com/BradLarson/GPUImage
  3. Stream out the chosen camera view. depending on motion detected

  Larson’s GPUImage framework works with an AVCaptureSession subclass. I’m only familiar with AVFoundation objects, but am a complete noob with it comes to VideoToolbox and some of the lower level iOS video stuff. Through googling, I kind of know that VTDecompressionSession is what I’d get from the WiFi camera. I have no clue how I can manipulate that to a usable form for my purposes.

  I’ve dug through stackoverflow answers such as : https://stackoverflow.com/a/29525001/7097455

  Very informative, but maybe I don’t even know to ask the correct questions