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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.

• Integrate the FFMPEG in android

  12 juillet 2016, par John Smith

  I’m trying to integrate FFMPEG into my android app(I am trying to implement a video cropper), I was following the steps from an Kevin Law’s answer here :

  quora question

  I have downloaded the android ndk.
  In the step two it says I should modify the package name which I did.
  It also says that I should modify the flags for codecs I’m interested in.
  So my first question is

  1. Which codecs would I need to work with mp4, 3gp and maybe avi files in android ?

  I tried to leave everything by default and build with build.sh script but it fails on the line where I have changed the package name

      FLAGS="$FLAGS --soname-prefix=/data/data/cropit.dassem.com.videocropper/lib/"

  with

  Unknown option "--soname-prefix=/data/data/cropit.dassem.com.videocropper/lib/".
  
  See ./configure --help for available options.

  2. Now is there anyone familiar with FFMPEG integration and sees something that I have missed ?

  I do not want to use the pre-compiled FFMPEG libraries because they are really big, the ones I found take around 15 MB of space. I’ve read somewhere that if i’ll compile and integrate FFMPEG myself it will be much smaller.

  3. Are there any easier ways of cropping video on android ?

  Maybe there is no point in dealing with this, which proves quite a pain I must admit, and there is an easier solution available ?

• Revision 679e4abdd5 : Initial version of alpha channel support This is a mostly-working implementatio

  16 mai 2013, par John Koleszar

  Changed Paths :
   Modify /configure

  
   Modify /vp9/common/vp9_alloccommon.c

  
   Modify /vp9/common/vp9_blockd.h

  
   Modify /vp9/common/vp9_extend.c

  
   Modify /vp9/common/vp9_mbpitch.c

  
   Modify /vp9/common/vp9_onyxc_int.h

  
   Modify /vp9/common/vp9_postproc.c

  
   Modify /vp9/common/vp9_reconinter.c

  
   Modify /vp9/common/vp9_reconinter.h

  
   Modify /vp9/encoder/vp9_encodeframe.c

  
   Modify /vp9/encoder/vp9_encodemb.c

  
   Modify /vp9/encoder/vp9_lookahead.c

  
   Modify /vp9/encoder/vp9_onyx_if.c

  
   Modify /vp9/encoder/vp9_onyx_int.h

  
   Modify /vp9/encoder/vp9_quantize.c

  
   Modify /vp9/encoder/vp9_rdopt.c

  
   Modify /vp9/encoder/vp9_temporal_filter.c

  
   Modify /vp9/vp9_iface_common.h

  
   Modify /vpx_scale/generic/yv12config.c

  
  
  Initial version of alpha channel support

  This is a mostly-working implementation of an extra channel in the
  bitstream. Configure with —enable-alpha to test. Notable TODOs :

  - Add extra channel to all mismatch tests, PSNR, SSIM, etc
  - Configurable subsampling
  - Variable number of planes (currently always uses all 4)
  - Loop filtering
  - Per-plane lossless quantizer
  - ARNR support

  This implementation just uses the same contents as the Y channel
  for the A channel, due to lack of content and general pain in
  playing back 4 channel content. A later patch will use the actual
  alpha channel passed in from outside the codec.

  Change-Id : Ibf81f023b1c570bd84b3064e9b4b8ae52e087592