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• iOS SDK avcodec_decode_video Optimization

  6 août 2013, par Johny Cage

  I've recently started a project that relies on streaming FLV directly to an iOS device. As most famous i went with ffmpeg (and an iOS wrapper - kxmovie). To my surprise iPhone 4 is incapable of playing even SD low-bitrate FLV videos. The current implementation i'm using is decoding the video/audio/sub frames in dispatch_async while loop and copies the YUV frame data to a object, where the object is parsed to 3 textures - Y/U/V (in case of RGB color space - just parse the data) and rendered on screen. After much trial and error, i've decided to kill the whole rendering pipeline and leave only the avcodec_decode_video2 function to run. Surprisingly the FPS did not improve and videos are still unplayable.

  My question is : What can i do to improve the performance of avcodec_decode_video2 ?

  Note :
  I've tried a few commercial apps and they play the same file perfectly fine with no more than 50-60% cpu usage.

  The library is based off the 1.2 branch and this is are the build args :

  '--arch=arm',
  
  '--cpu=cortex-a8',
  
  '--enable-pic',
  
  "--extra-cflags='-arch armv7'",
  
  "--extra-ldflags='-arch armv7'",
  
  "--extra-cflags='-mfpu=neon -mfloat-abi=softfp -mvectorize-with-neon-quad'",
  
  '--enable-neon',
  
  '--enable-optimizations',
  
  '--disable-debug',
  
  '--disable-armv5te',
  
  '--disable-armv6',
  
  '--disable-armv6t2',
  
  '--enable-small',
  
  '--disable-ffmpeg',
  
  '--disable-ffplay',
  
  '--disable-ffserver',
  
  '--disable-ffprobe',
  
  '--disable-doc',
  
  '--disable-bzlib',
  
  '--target-os=darwin',
  
  '--enable-cross-compile',
  
  #'--enable-nonfree',
  
  '--enable-gpl',
  
  '--enable-version3',

  And according to Instruments the following functions take about 30% CPU usage each :

  Running Time    Self        Symbol Name
  
  37023.9ms   32.3%   13874,8                   ff_h264_decode_mb_cabac
  
  34626.2ms   30.2%   9194,7                    loop_filter
  
  29430.0ms   25.6%   173,8                     ff_h264_hl_decode_mb

• ffmpeg ios, decoding rtsp stream causes memory leak

  5 août 2013, par Simone M

  i have an ios application that stream a rtsp video via network using ffmpeg library.
  In random time i have a crash without error message, the only message in console is "Memory warning".
  Using instrument i detect some memory leaks, this link a screenshot about error : http://vincentvega.it/iphone/video.png, i think the problem is in the point of code where i make uiimage to show on screen :

  - (void)convertFrameToRGB
  
  {
  
      sws_scale(img_convert_ctx,
  
                pFrame->data,
  
                pFrame->linesize,
  
                0,
  
                pCodecCtx->height,
  
                picture.data,
  
                picture.linesize);
  
  
  
  }
  
  
  
  - (UIImage *)imageFromAVPicture:(AVPicture)pict width:(int)width height:(int)height
  
  {
  
      CGBitmapInfo bitmapInfo = kCGBitmapByteOrderDefault;
  
      CFDataRef data = CFDataCreateWithBytesNoCopy(kCFAllocatorDefault, pict.data[0], pict.linesize[0]*height,kCFAllocatorNull);
  
      CGDataProviderRef provider = CGDataProviderCreateWithCFData(data);
  
      CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB();
  
      CGImageRef cgImage = CGImageCreate(width, 
  
                                         height, 
  
                                         8, 
  
                                         24, 
  
                                         pict.linesize[0], 
  
                                         colorSpace, 
  
                                         bitmapInfo, 
  
                                         provider, 
  
                                         NULL, 
  
                                         NO, 
  
                                         kCGRenderingIntentDefault);
  
      CGColorSpaceRelease(colorSpace);
  
      UIImage *image = [[UIImage alloc] initWithCGImage:cgImage];
  
  
  
  
  
  
  
      return [image autorelease];
  
  }

  how can i detect the function that causes memory problem ?

  SOLVED ! I just neeed to add the following code in "imagefromavcapture" :

  CGImageRelease(cgImage);
  
      CGDataProviderRelease(provider);
  
      CFRelease(data);

• hls live streaming using ffmpeg in iOS

  25 mars 2015, par chetan

  I am new to ffmpeg and I am trying to create live streaming app (HLS) and I want Live broadcasting rather than VOD.

  I am able to use ffmpeg through terminal and create .ts files from m4v but I am not getting how to achieve the same thing in iPhone.

  My approach is to create .ts files at iPhone end and then send it to server.

  I am not sure if this approach is correct, If this correct how I can create .ts files then otherwise what’s the right approach ?