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• Looking for method to combine images to make a video through phonegap platform for android and ios

  28 novembre 2012, par Pat

  I'm looking to write an application that could combine images and then to form a video. I'm working with Phonegap framework to be available for use on Android and IOS.

  My question is what sort of process is involved to achieve this ?

  At this stage I've tried to read about ffmpeg, most of the questions existing on stackoverflow talk of having to get the source, compiling to make a series of libraries for use. With those libraries it needs to be tied in with the Android/IOS libraries ? (I notice there is an 'android.jar' with the project file in eclipse. Would it exist in there ?) Afterwards my confusion lies with how is this implemented into Phonegap. Develop a plugin ?

  Just to add, libav according to wiki, has hardware accelerated H.264 decoding whilst using x.264 for encoding for Android. How does that work ? Is this something accessed from libav libraries and then have to compiled in within the android.jar ?

  I may have confused terms in trying to describe what I do not know.

  Any help would be appreciated.

• How to batch convert mp4 files to ogg with ffmpeg using a bash command or Ruby

  3 avril 2013, par TJ Sherrill

  I am running a OSX, don't know tons about video conversions. But I have like 200 videos that are all in mp4 format and won't play in Firefox. I need to convert them to ogg to use the html5 video tag.

  These files live in a folder structure that makes it hard to do files one at a time. I would like the bash command or Ruby command to go through all child folders and find all .mp4's and convert them.

  I found one reference of how to do this with Google : http://athmasagar.wordpress.com/2011/05/12/a-bash-script-to-convert-mp4-files-to-oggogv/

  #!/bin/bash
  
  for f in $(ls *mp4 | sed ‘s/\(.*\)\..*/\1/’)
  
  do
  
  ffmpeg -i $f.mp4 -acodec vorbis -vcodec libtheora $f.ogg
  
  done

  But have no idea how to convert this from linux to osx.

• Displaying YUV420 data using Opengles shader is too slow

  28 novembre 2012, par user1278982

  I have a child thread called A to decode video using ffmpeg on iPhone 3GS, another thread called B to display yuv data, in thread B, I used glSubTexImage2D to upload Y U V textures, and then convert yuv data to RGB in shader, but the frame rate in the decode thread is only 15fps.Why ?

  Update :
  The frame size is 720 * 576.
  I also found something interesting that if I didn't start the thread displaying the YUV data, the frame rate calculated in the decode thread is 22 fps,otherwise 15 fps.So I think that my displaying method must be inefficient.the code as below.

  I have a callback in the decode thread :

  typedef struct _DVDVideoPicture
  
  {
  
     char *plane[4];
  
     int iLineSize[4];
  
  }DVDVideoPicture;
  
  
  
  void YUVCallBack(void *pYUVData, void *pContext)
  
  {
  
     VideoView *view = (VideoView *)pContext;
  
     [view.glView copyYUVData:(DVDVideoPicture *)pData];
  
     [view calculateFrameRate];
  
  }

  The copyYUVData method extract the y u v planes separately. The following is displaying thread method.