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• Record stream from camera to file / live stream

  8 juillet 2015, par sandman

  I’m trying to stream my camera feed to a webpage. For this I’m trying to use FFmpeg to encode the data from the camera preview and output to a file. (I’m new to this, so I’m only trying to write to a file now)

  The camera feed is captured and it starts writing to a flv file but, it freezes my app after a few seconds and the resulting flv is about half a second long.

  bos is a BufferedOutputStream which servers as an input stream for the Ffmpeg ProcessBuilder.

  When a button is clicked, the Ffmpeg process is executed and the writing begins.
  But as I said, it freezes the app after a while. I tried running the Ffmpeg process in an AsyncTask, but it keeps saying FileDescriptor closed, but the app does not freeze when I do it this way, and there is no output as well.

  Here is my onPreviewFrame() :

  public void onPreviewFrame(byte[] b, Camera c) {
  
      if (recording) {
  
          int previewFormat = p.getPreviewFormat();
  
          Log.v(LOGTAG, "Started Writing Frame");
  
  
  
          im = new YuvImage(b, previewFormat, p.getPreviewSize().width, p.getPreviewSize().height, null);
  
          Rect r = new Rect(0, 0, p.getPreviewSize().width, p.getPreviewSize().height);
  
          if (bos != null)
  
              im.compressToJpeg(r, 40, bos);
  
          im = null;
  
  
  
          Log.v(LOGTAG, "Finished Writing Frame");
  
      }
  
  }

  If I can get this fixed, I can probably move on to live streaming.

• NSTask and FFMpeg losing output

  16 novembre 2011, par Morgan

  I'm trying to call ffmpeg from NSTask in objective-c. I execute the ffmpeg command in terminal and it works flawlessly every time. I make the same command using NSTask, and it never gives me the whole output. It cuts it off half way through the output, at a seemingly random spot every time. Here is my code.

      - (void)applicationDidFinishLaunching:(NSNotification *)aNotification
  
  {
  
      NSString* ffmpegPath = [[NSBundle mainBundle] pathForResource:@"ffmpeg" ofType:@""];
  
      NSString* path = @"test.mov";
  
  
  
      NSTask *task = [[NSTask alloc] init];
  
      NSArray *arguments = [NSArray arrayWithObjects: @"-i", path, nil];
  
      NSPipe *pipe = [NSPipe pipe];
  
      NSFileHandle * read = [pipe fileHandleForReading];
  
  
  
      [task setLaunchPath: ffmpegPath];
  
      [task setArguments: arguments];
  
      [task setStandardOutput: pipe];
  
      [task launch];
  
      [task waitUntilExit];
  
  
  
      NSData* data = [read readDataToEndOfFile];
  
      NSString* stringOutput = [[NSString alloc] initWithData:data encoding:NSUTF8StringEncoding];
  
  
  
  
  
      NSLog(@"%@", stringOutput);
  
      NSLog(@"%i", [task terminationStatus]);
  
      NSLog(@"DONE");
  
  }

• aarch64 : vp8 : Optimize vp8_idct_add_neon for aarch64

  31 janvier 2019, par Martin Storsjö

  aarch64 : vp8 : Optimize vp8_idct_add_neon for aarch64
  The previous version was a pretty exact translation of the arm
  
  version. This version does do some unnecessary arithemetic (it does
  
  more operations on vectors that are only half filled ; it does 4
  
  uaddw and 4 sqxtun instead of 2 of each), but it reduces the overhead
  
  of packing data together (which could be done for free in the arm
  
  version).
  This gives a decent speedup on Cortex A53, a minor speedup on
  
  A72 and a very minor slowdown on Cortex A73.
  Before :        Cortex A53    A72    A73
  
  vp8_idct_add_neon :   79.7   67.5   65.0
  
  After :
  
  vp8_idct_add_neon :   67.7   64.8   66.7
  Signed-off-by : Martin Storsjö <martin@martin.st>
  

  • [DBH] libavcodec/aarch64/vp8dsp_neon.S