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• Capturing frames from h264 video in android froyo

  21 janvier 2013, par Grzegorz Patyn

  The problem : "How to capture image frames from video in Android api level 8"
  Description : In api level 10 there was released MediaDataRetriever class, which has method "captureFrame". It doesn't work in api level 8.
  I made many studying around a problem :
  Trying to install android-support-v13 library - fail, because it doesn't have MediaDataRetriever class.
  I tried using ffmpeg.
  I compiled ffmpeg using ndk, for arm processors in many ways. Basically You can have problem Collect2: cannot find ld in ndkr8d, so i finally compiled with ndkr8b and got ffmpeg executable file.
  Now, having executable ffmpeg from this project : https://github.com/guardianproject/android-ffmpeg-java
  there is a problem :
  The library needs root access but i don't have it. I want my app work on most android apps. In order to execute ffmpeg, i do :

      String path = ( Environment.getExternalStorageDirectory() ).getAbsolutePath();
  
  String ffmpegBin = path+"/test/ffmpeg";
  
  String komenda = ffmpegBin+" -vframes 1 -ss 10 -i video.mp4 -f image2 -vcodec mjpeg "+path+"/test/frame%d.jpg";
  
  Runtime rt = Runtime.getRuntime();
  
  try {
  
      Process proc = rt.exec("chmod 700"+ffmpegBin);
  
      rt.exec(ffmpegBin,null,null);
  
  } catch (IOException e) {
  
      // TODO Auto-generated catch block
  
      e.printStackTrace();
  
  }

  Expecting to run ffmpeg command.
  I get the following error :

     01-21 15:29:24.129: W/System.err(10051): java.io.IOException: Error running exec(). Command: [/mnt/sdcard/test/ffmpeg] Working Directory: null Environment: null
  
  01-21 15:29:24.137: W/System.err(10051):    at java.lang.ProcessManager.exec(ProcessManager.java:226)
  
  01-21 15:29:24.137: W/System.err(10051):    at java.lang.Runtime.exec(Runtime.java:196)
  
  01-21 15:29:24.137: W/System.err(10051):    at java.lang.Runtime.exec(Runtime.java:285)
  
  01-21 15:29:24.137: W/System.err(10051):    at com.example.ff.MainActivity.onStart(MainActivity.java:50)
  
  01-21 15:29:24.137: W/System.err(10051):    at android.app.Instrumentation.callActivityOnStart(Instrumentation.java:1129)
  
  01-21 15:29:24.137: W/System.err(10051):    at android.app.Activity.performStart(Activity.java:3781)
  
  01-21 15:29:24.137: W/System.err(10051):    at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2641)
  
  01-21 15:29:24.137: W/System.err(10051):    at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2684)
  
  01-21 15:29:24.137: W/System.err(10051):    at android.app.ActivityThread.access$2300(ActivityThread.java:126)
  
  01-21 15:29:24.137: W/System.err(10051):    at android.app.ActivityThread$H.handleMessage(ActivityThread.java:2038)
  
  01-21 15:29:24.137: W/System.err(10051):    at android.os.Handler.dispatchMessage(Handler.java:99)
  
  01-21 15:29:24.137: W/System.err(10051):    at android.os.Looper.loop(Looper.java:123)
  
  01-21 15:29:24.137: W/System.err(10051):    at android.app.ActivityThread.main(ActivityThread.java:4632)
  
  01-21 15:29:24.137: W/System.err(10051):    at java.lang.reflect.Method.invokeNative(Native Method)
  
  01-21 15:29:24.137: W/System.err(10051):    at java.lang.reflect.Method.invoke(Method.java:521)
  
  01-21 15:29:24.137: W/System.err(10051):    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:858)
  
  01-21 15:29:24.137: W/System.err(10051):    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616)
  
  01-21 15:29:24.137: W/System.err(10051):    at dalvik.system.NativeStart.main(Native Method)
  
  01-21 15:29:24.137: W/System.err(10051): Caused by: java.io.IOException: Permission denied
  
  01-21 15:29:24.137: W/System.err(10051):    at java.lang.ProcessManager.exec(Native Method)
  
  01-21 15:29:24.137: W/System.err(10051):    at java.lang.ProcessManager.exec(ProcessManager.java:224)
  
  01-21 15:29:24.137: W/System.err(10051):    ... 17 more

  In test directory there is a video.mp4 file, which is a valid file. The directory also contains ffmpeg binary compiled for arm with ndkr8b from this source : https://github.com/guardianproject/android-ffmpeg

  Is there any way to use compiled ffmpeg in applications, can i set some permissions in AndroidManifest etc. without su ?

• Android video conversion [on hold]

  28 octobre 2013, par Jeffrey Grima

  I am a student who is doing his bachelors degree thesis. I need to implement a mobile application to convert video files from one format to another and also using a mobile service to do the same thing and compare how long did it take to perform the same tests but with different approaches.

  After doing some research on how to implement the conversion on the mobile application I have only found FFMpeg. I would like to know if any of you guys have in mind like other video converting API`s for android or something that i should consider before submitting my proposal.

• X264 & ARM encoding on Android

  20 janvier 2013, par Tishu

  I recently built a Video encoding class that runs on Android using ffmpeg and native code. I am surprised by the time it takes to encode a video, about 1 frame / second at best. I have tried with x264 and settings optimised for speed and with mpeg as well - no real difference.

  The x264 library now has support for ARM architecture and is meant to be quite efficient on these boasting over 20fps encoding speed. I am not sure I am using it correctly. Here the script I use for compiling :

  ./configure --prefix=$PREFIX \
  
  --enable-shared \
  
  --enable-static \
  
  --disable-gpac \
  
  --enable-debug \
  
  --extra-cflags=" -I$ARM_INC -fPIC -DANDROID -fpic -mthumb-interwork -ffunction-sections -funwind-tables -fno-short-enums -D__ARM_ARCH_5__ -D__ARM_ARCH_5T__ -D__ARM_ARCH_5E__ -D__ARM_ARCH_5TE__ -Wno-psabi -march=armv5te -msoft-float -mthumb -O3 -fomit-frame-pointer -fno-strict-aliasing -finline-limit=64 -DANDROID -Wa,--noexecstack -MMD -MP " \
  
  --extra-ldflags=" -nostdlib -Bdynamic -Wl,--no-undefined -Wl,-z,noexecstack -Wl,-z,nocopyreloc -Wl,-soname,/usr/lib/libz.so -Wl,-rpath-link=$ARM_LIB,-dynamic-linker=/system/bin/linker -L$ARM_LIB -lc -lm -ldl -lgcc" \
  
  --cross-prefix=${ARM_PRE}- \
  
  --disable-asm \
  
  --host=arm-linux \

  I believe the last line should so what I am after ie enable ARM optimisations. Maybe I am missing something.

  For info I am encoding a 640x480 video on a Nexus 7 tablet. Here are my encoder settings (x264)

  c->gop_size       = 12;
  
  c->pix_fmt        = PIX_FMT_YUV420P;
  
  c->max_b_frames   = 0;
  
  c->scenechange_threshold = 0;
  
  c->rc_buffer_size = 0;

  Thanks