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• Removing audio noise (hissing) in C++ from 16bit PCM

  4 juillet 2016, par hockeyislife

  I have been going through the posts of stack overflow but I am not understanding how to remove hissing sound from my audio being grabbed from the microphone.

  I implemented a simple low pass filter but I must be doing something wrong.

  unsigned short *buf = "audio data in PCM format";
  
  double out_sample = 0;
  
  int sample_size = "number of samples of audio";
  
  for (int n = 0; n < sample_size/2; n++)
  
  {
  
      out_sample = (out_sample * 90 + buf[n] * 10) / 100;
  
      buf[n] = (unsigned short) out_sample;
  
  }

  The above produces really corrupt audio.

  I know I need to make a low pass filter on the PCM data. Can anyone shed some light into what I am doing wrong.

  Thanks in advance.

• Working Directory : null Environment : null

  8 février 2017, par Mert

  I am trying to use ffmpeg.so on Android I am getting Working Directory : null Environment : null error.

  try {
  
      Process p = Runtime.getRuntime().exec("/data/data/com.example.foo/files/ffmpeg -f image2 -i "
  
  + Environment.getExternalStorageDirectory().getAbsolutePath() + "/img/b%d.jpg " 
  
  + Environment.getExternalStorageDirectory().getAbsolutePath() + "/DCIM/Camera/a444.mp4");   
  
  } catch (IOException e) {
  
      e.printStackTrace();
  
  }

  ERROR LOG

  04-09 01:50:45.683: I/Adreno-EGL(18393): : EGL 1.4 QUALCOMM Build: I0404c4692afb8623f95c43aeb6d5e13ed4b30ddbDate: 11/06/13
  
  04-09 01:50:45.713: D/OpenGLRenderer(18393): Enabling debug mode 0
  
  04-09 01:53:56.487: D/dalvikvm(18551): Trying to load lib /data/app-lib/com.example.sodeneme-1/libffmpeg.so 0x423d7d00
  
  04-09 01:53:56.487: D/dalvikvm(18551): Added shared lib /data/app-lib/com.example.sodeneme-1/libffmpeg.so 0x423d7d00
  
  04-09 01:53:56.487: D/dalvikvm(18551): No JNI_OnLoad found in /data/app-lib/com.example.sodeneme-1/libffmpeg.so 0x423d7d00, skipping init
  
  04-09 01:53:56.537: W/System.err(18551): java.io.IOException: Error running exec(). Command: [/data/data/com.example.sodeneme/files/ffmpeg, -f, image2, -i, /storage/emulated/0/img/b%d.jpg, /storage/emulated/0/DCIM/Camera/a444.mp4] Working Directory: null Environment: null
  
  04-09 01:53:56.537: W/System.err(18551):    at java.lang.ProcessManager.exec(ProcessManager.java:211)
  
  04-09 01:53:56.537: W/System.err(18551):    at java.lang.Runtime.exec(Runtime.java:173)
  
  04-09 01:53:56.537: W/System.err(18551):    at java.lang.Runtime.exec(Runtime.java:246)
  
  04-09 01:53:56.537: W/System.err(18551):    at java.lang.Runtime.exec(Runtime.java:189)
  
  04-09 01:53:56.537: W/System.err(18551):    at com.example.sodeneme.MainActivity.onCreate(MainActivity.java:40)
  
  04-09 01:53:56.537: W/System.err(18551):    at android.app.Activity.performCreate(Activity.java:5231)
  
  04-09 01:53:56.537: W/System.err(18551):    at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1087)
  
  04-09 01:53:56.537: W/System.err(18551):    at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2159)
  
  04-09 01:53:56.537: W/System.err(18551):    at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2245)
  
  04-09 01:53:56.537: W/System.err(18551):    at android.app.ActivityThread.access$800(ActivityThread.java:135)
  
  04-09 01:53:56.537: W/System.err(18551):    at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1196)
  
  04-09 01:53:56.537: W/System.err(18551):    at android.os.Handler.dispatchMessage(Handler.java:102)
  
  04-09 01:53:56.537: W/System.err(18551):    at android.os.Looper.loop(Looper.java:136)
  
  04-09 01:53:56.537: W/System.err(18551):    at android.app.ActivityThread.main(ActivityThread.java:5017)
  
  04-09 01:53:56.537: W/System.err(18551):    at java.lang.reflect.Method.invokeNative(Native Method)
  
  04-09 01:53:56.537: W/System.err(18551):    at java.lang.reflect.Method.invoke(Method.java:515)
  
  04-09 01:53:56.537: W/System.err(18551):    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:779)
  
  04-09 01:53:56.537: W/System.err(18551):    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:595)
  
  04-09 01:53:56.537: W/System.err(18551):    at dalvik.system.NativeStart.main(Native Method)
  
  04-09 01:53:56.547: W/System.err(18551): Caused by: java.io.IOException: No such file or directory
  
  04-09 01:53:56.547: W/System.err(18551):    at java.lang.ProcessManager.exec(Native Method)
  
  04-09 01:53:56.547: W/System.err(18551):    at java.lang.ProcessManager.exec(ProcessManager.java:209)
  
  04-09 01:53:56.547: W/System.err(18551):    ... 18 more
  
  04-09 01:53:56.577: I/Adreno-EGL(18551): : EGL 1.4 QUALCOMM Build: I0404c4692afb8623f95c43aeb6d5e13ed4b30ddbDate: 11/06/13
  
  04-09 01:53:56.607: D/OpenGLRenderer(18551): Enabling debug mode 0

  PERMISSIONS

• Revision e890c2579b : add a context tree structure to encoder This patch sets up a quad_tree structur

  17 avril 2014, par Jim Bankoski

  Changed Paths :
   Modify /vp9/encoder/vp9_block.h

  
   Add /vp9/encoder/vp9_context_tree.c

  
   Add /vp9/encoder/vp9_context_tree.h

  
   Modify /vp9/encoder/vp9_encodeframe.c

  
   Modify /vp9/encoder/vp9_firstpass.c

  
   Modify /vp9/encoder/vp9_onyx_if.c

  
   Modify /vp9/vp9cx.mk

  
  
  add a context tree structure to encoder

  This patch sets up a quad_tree structure (pc_tree) for holding all of
  pick_mode_context data we use at any square block size during encoding
  or picking modes. That includes contexts for 2 horizontal and 2 vertical
  splits, one none, and pointers to 4 sub pc_tree nodes corresponding
  to split. It also includes a pointer to the current chosen partitioning.

  This replaces code that held an index for every level in the pick
  modes array including : sb_index, mb_index,
  b_index, ab_index.

  These were used as stateful indexes that pointed to the current pick mode
  contexts you had at each level stored in the following arrays

  array ab4x4_context[][][],
  sb8x4_context[][][], sb4x8_context[][][], sb8x8_context[][][],
  sb8x16_context[][][], sb16x8_context[][][], mb_context[][], sb32x16[][],
  sb16x32[], sb32_context[], sb32x64_context[], sb64x32_context[],
  sb64_context

  and the partitioning that had been stored in the following :
  b_partitioning, mb_partitioning, sb_partitioning, and sb64_partitioning.

  Prior to this patch before doing an encode you had to set the appropriate
  index for your block size ( switch statement), update it ( up to 3
  lookups for the index array value) and then make your call into a recursive
  function at which point you'd have to call get_context which then
  had to do a switch statement based on the blocksize, and then up to 3
  lookups based upon the block size to find the context to use.

  With the new code the context for the block size is passed around directly
  avoiding the extraneous switch statements and multi dimensional array
  look ups that were listed above. At any level in the search all of the
  contexts are local to the pc_tree you are working on (in ?).

  In addition in most places code that used to call sub functions and
  then check if the block size was 4x4 and index was > 0 and return
  now don't preferring instead to call the right none function on the inside.

  Change-Id : I06e39318269d9af2ce37961b3f95e181b57f5ed9