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• 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

• How to estimate bandwidth / speed requirements for real-time streaming video ?

  19 juin 2016, par Vivek Seth

  For a project I’m working on, I’m trying to stream video to an iPhone through its headphone jack. My estimated bitrate is about 200kbps (If i’m wrong about this, please ignore that).

  I’d like to squeeze as much performance out of this bitrate as possible and sound is not important for me, only video. My understanding is that to stream a a real-time video I will need to encode it with some codec on-the-fly and send compressed frames to the iPhone for it to decode and render. Based on my research, it seems that H.265 is one of the most space efficient codecs available so i’m considering using that.

  Assuming my basic understanding of live streaming is correct, how would I estimate the FPS I could achieve for a given resolution using the H.265 codec ?

  The best solution I can think of it to take a video file, encode it with H.265 and trim it to 1 minute of length to see how large the file is. The issue I see with this approach is that I think my calculations would include some overhead from the video container format (AVI, MKV, etc) and from the audio channels that I don’t care about.

• iFrameExtractor no ffmpeg with build_universal script

  15 août 2016, par AlecGamble

  I’m trying to follow this tutorial on how to extract the frames from an iphone video :

  http://www.codza.com/extracting-frames-from-movies-on-iphone#more-343

  It says to do the following :

  • open Terminal
  • clone the repository : git clone git://github.com/lajos/iFrameExtractor.git
  • go to the ffmpeg folder in the project : cd iFrameExtractor/ffmpeg
  • build the ffmpeg libraries : ./build_universal

  So there’s no ffmpeg folder in iFrameExtractor after cloning the repository so I went to the github page and it says to download the latest version of ffmpeg and move to to the ffmpeg folder (I presume it just means within iFrameExtractor) :

  • Download the latest ffmpeg (0.11.1 tested) :
    git clone git://source.ffmpeg.org/ffmpeg.git

  So I’ve done that but there’s no file or directory when I try to run ./build_universal and I can see that there isn’t.

  Any ideas what I’m doing wrong ?

  Alternatively I was also looking at just installing ffmpeg-ios and trying to extract the frames myself :

  https://github.com/kewlbear/FFmpeg-iOS-build-script

  and I’ve run the script so I’ve got that folder in my xcode project as well but I’m unsure on how to link it properly ?