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• Fast green screen video processing on android device

  17 mars 2015, par Si-N

  I have written an app in iOS that takes two video sources, one with moving character on a green screen and any other video. The program then uses the GPUImage framework to add a chroma key shader via OpenGL ES 2 and then merges each frame (so the bottom frame now shows where the green pixels are) and outputs to a new video file. This happens very quickly, faster than real time.

  I have now been tasked with porting the app to Android. I thought it would be fairly straightforward. After doing some research I think I am wrong. There is an Android port of GPUImage but it does not handle video at the moment. I have done some research and come up with a very basic idea.

  I was wondering if you think this approach is feasible :

  Convert one video file to match resolution and type of other video using ffmpeg or JavaCV wrappers.

  Read frame by frame of each video using ffmpeg as MediaMetadataRetriever is very slow and convert into some RGB format. Use shader to apply chroma key effect so both frames are merged.

  Use ffmpeg to output result to a new file.

  This sounds slow, but if it sounds feasible I will try it out. I am not at all sure about making sure the 2 video resolutions / bitrate etc match. One video will be fixed at 1280 * 720 and the other video source will come from the camera on the device so will be variable. Also I think ffmpeg means using NDK which is a whole world of pain I wanted to avoid.

  I have a headache thinking about it. Any advice would be greatly appreciated.

• Unable toopen symbol file. Error (20) : Not a directory

  1er avril 2015, par grzebyk

  I am using ffmpeg library on android to stream live video feed. I have complied ffmpeg for android following roman10 instructions. The application is working correctly - it connects to the server, download the feed, transcode it, rescale it and displays on the device’s screen. However after a certain random moment the app crashes with Fatal signal 11 (SIGSEGV), code 1. I have used ndk-stack to find the source of the problem. Here is the crash dump :

  ********** Crash dump: **********
  
  Build fingerprint: 'google/hammerhead/hammerhead:5.0.1/LRX22C/1602158:user/release-keys'
  
  pid: 25241, tid: 25317, name: AsyncTask #5  >>> com.grzebyk.streamapp <<<
  
  signal 11 (SIGSEGV), code 1 (SEGV_MAPERR), fault addr 0x98e74c9c
  
  Stack frame #00 pc 00047924  /data/app/com.grzebyk.streamapp-1/lib/arm/libswscale-3.so: Unable to open symbol file /Users/grzebyk/Documents/New_Eclipse_Projects/StreamApp/libs/armeabi/libStreamApp.so/libswscale-3.so. Error (20): Not a directory
  
  Stack frame #01 pc 00034be8  /data/app/com.grzebyk.streamapp-1/lib/arm/libswscale-3.so (sws_scale+2648): Unable to open symbol file /Users/grzebyk/Documents/New_Eclipse_Projects/StreamApp/libs/armeabi/libStreamApp.so/libswscale-3.so. Error (20): Not a directory

  My native code is located in the StreamApp.cpp file. For me it looks like the app is trying to access libswscale-3.so (part of the ffmpeg) located inside the libStreamApp.so. This seems weird for me…

  All the ffmpeg’s .so files are located in /libs/armeabi/lib*.so. Naturally this includes the "missing" libswscale-3.so. The most disturbing thing is a fact that the app is working perfectly, but it crashes suddenly and it does not need any specific trigger to do so.

  What can I do to either put libswscale-3.so inside labStreamApp.so or to avoid referencing one .so file from another ?

• Révision 23137 : report de r23136

  24 août 2016, par brunobergot@gmail.com

  fix css pour le sélecteur de rubrique

  ne pas appliquer de max-height au select (on traine ça depuis un moment) afin de ne pas tronquer le contenu de celui-ci sur certains environnements