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• VBV-CBR and ABR in X264

  11 décembre 2013, par xkfz007

  In x264 VBV-CBR RC mode is based on ABR and vbv-maxrate and vbv-bufsize are set. On the basis of frame QP decided by ABR, the MB row QP is decided by VBV-CBR for each row. I test these two modes and the command lines are listed: ABR: -o BasketballDrill_832x480_50_20131210102507.264 BasketballDrill_832x480_50.yuv 832x480 --fps 50 --frames 300 --bitrate 1120 --profile baseline --threads -1 -I 50 -v --psnr VBV-CBR: -o BasketballDrill_832x480_50_20131210102507_mb.264 BasketballDrill_832x480_50.yuv 832x480 --fps 50 --frames 300 --bitrate 1120 --vbv-maxrate 1120 --vbv-bufsize 1680 --profile baseline --threads 1 -I 50 -v --psnr

  The final results are: ABR: Y-PSNR 31.530dB, bitrate 1146.93kbps VBV-CBR: Y-PSNR 31.728dB, bitrate 1230.25kbps Compared to ABR, VBV-CBR achieved 4.9% bitrate promotion and 0.198dB PSNR promotion. But the PSNR promotion is lower than bitrate (1% bitrate=0.05dB).

  Having talked so much, I just want to ask what is the advantage of VBV-CBR compared ABR? If ABR can get the reasonable results, why the VBV-cBR is needed? In my opinion, VBV-CBR maybe can promote the subjective quality owing to deciding the QP for each MB row. But the bitrate also rises. Also I have compared some frames of the two modes, they are almost the same. Maybe there are some situations that are fit for VBV-CBR and I don't know. So guys, give me, the new to x264, some professional explanation.

• How to know if x264 uses multiple processors Windows

  3 décembre 2013, par fessy

  I have Linphone open source application that uses x264 encoder. By default it runs on one thread:

  x264_param_t *params= ..... 
  params->i_threads=1;
  

  I added ability to use all processors:

  long num_cpu=1;
  SYSTEM_INFO sysinfo;
  GetSystemInfo( &sysinfo );
  num_cpu = sysinfo.dwNumberOfProcessors;
  params->i_threads=num_cpu;  
  

  The question is how do I know that during video streaming x264 runs on (in my case) 4 processors?

  Because from Task Manager -> Performance -> CPU usage history doesn't clear.

  I use windows 7

  Thanks,

• Compiling x264 for iOS 5

  28 novembre 2013, par user1220345

  I'm trying to compile the latest version of libx264 to iOS 5 arm.

  In mid-2010, the Gabriel script for building worked.

  It doesn't anymore.

  It says "No working C compiler found."

  Can anyone give me straight answer? It's 2012 and no one in google seems to have compiled it.

• I'm creating opensource GPL H264 encoding lib/app (based on x264) do I need to pay for the license ?

  27 novembre 2013, par Spender

  I'm creating opensource GPL H264 encoding lib/app (based on x264) do I need to pay for the license?

• link error Xcode libx264.a ARM

  19 novembre 2013, par user1558688

  I'm trying to build libx264.a to run on my iphone 4s ( running iOS 6.1.3 )

  I'm building it using the MACOSX 10.9 Terminal application:

  CC=/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/clang ./configure 
  --host=arm-apple-darwin 
  --sysroot=/Applications/Xcode.app/Contents/Developer/Platforms/iPhoneOS.platform/Developer/SDKs/iPhoneOS7.0.sdk 
  --prefix=armv7 
  --extra-cflags='-no-integrated-as -arch armv7' 
  --extra-ldflags="-L/Applications/Xcode.app/Contents/Developer/Platforms/iPhoneOS.platform/Developer/SDKs/iPhoneOS7.0.sdk/usr/lib/system -arch armv7" 
  --enable-pic --enable-static
  

  Which guives me the output:

  platform:      ARM
  system:        MACOSX
  cli:           yes
  libx264:       internal
  shared:        no
  static:        yes
  asm:           yes
  interlaced:    yes
  avs:           avxsynth
  lavf:          no
  ffms:          no
  mp4:           no
  gpl:           yes
  thread:        posix
  opencl:        yes
  filters:       crop select_every 
  debug:         no
  gprof:         no
  strip:         no
  PIC:           yes
  bit depth:     8
  chroma format: all
  

  Then I run 'make' and it generates a libx264.a archive.

  So far, so good.

  On my Xcode (Version 5.0.2 (5A3005)) application I set:

  1) Build Settings -> Header Search Path -> x264 parent directory (../x264 )
  2) Build Phases -> Link Library with Binaries -> Add Other... ( ../x264/libx264.a )
  3) Build Settings -> Other Linker Flags: -ObjC

  In my AppDelegate.mm:

  #import "AppDelegate.h"
  #import "x264.h"
  
  @implementation AppDelegate
  
  - (BOOL)application:(UIApplication *)application 
  didFinishLaunchingWithOptions:(NSDictionary *)launchOptions
  {    
      x264_param_t x264param;
      x264_param_default(&x264param);
  
      // Override point for customization after application launch.
      return YES;
  }
  
  ...
  

  When i try to run it on the device I get the error:

  Undefined symbols for architecture armv7:
    "x264_param_default(x264_param_t*)", referenced from:
    -[AppDelegate application:didFinishLaunchingWithOptions:] in AppDelegate.o
  ld: symbol(s) not found for architecture armv7
  clang: error: linker command failed with exit code 1 
  (use -v to see invocation)
  

  Here is the command invoked by xcode:

  Ld /Users/danieldantas/Library/Developer/Xcode/DerivedData/testingCpp-bvawshyhjcybwvadwwwjqxuomjts/Build/Products/Debug-iphoneos/testingCpp.app/testingCpp normal armv7
  cd /Users/danieldantas/Desktop/projects/testingCpp
  setenv IPHONEOS_DEPLOYMENT_TARGET 6.0
  setenv PATH "/Applications/Xcode.app/Contents/Developer/Platforms/iPhoneOS.platform/Developer/usr/bin:/Applications/Xcode.app/Contents/Developer/usr/bin:/usr/bin:/bin:/usr/sbin:/sbin"
  /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/clang++ -arch armv7 -isysroot 
  /Applications/Xcode.app/Contents/Developer/Platforms/iPhoneOS.platform/Developer/SDKs/iPhoneOS7.0.sdk 
  -L/Users/danieldantas/Library/Developer/Xcode/DerivedData/testingCpp-bvawshyhjcybwvadwwwjqxuomjts/Build/Products/Debug-iphoneos 
  -L/Users/danieldantas/Desktop/projects/testingCpp -L/Users/danieldantas/Desktop/projects/x264 
  -F/Users/danieldantas/Library/Developer/Xcode/DerivedData/testingCpp-bvawshyhjcybwvadwwwjqxuomjts/Build/Products/Debug-iphoneos 
  -filelist /Users/danieldantas/Library/Developer/Xcode/DerivedData/testingCpp-bvawshyhjcybwvadwwwjqxuomjts/Build/Intermediates/testingCpp.build/Debug-iphoneos/testingCpp.build/Objects-normal/armv7/testingCpp.LinkFileList 
  -dead_strip -ObjC -stdlib=libc++ -fobjc-arc -fobjc-link-runtime -miphoneos-version-min=6.0 -lx264 -framework CoreGraphics -framework UIKit -framework Foundation -Xlinker -dependency_info -Xlinker 
  /Users/danieldantas/Library/Developer/Xcode/DerivedData/testingCpp-bvawshyhjcybwvadwwwjqxuomjts/Build/Intermediates/testingCpp.build/Debug-iphoneos/testingCpp.build/Objects-normal/armv7/testingCpp_dependency_info.dat -o 
  /Users/danieldantas/Library/Developer/Xcode/DerivedData/testingCpp-bvawshyhjcybwvadwwwjqxuomjts/Build/Products/Debug-iphoneos/testingCpp.app/testingCpp
  

  Any idea how to fix this ?

  Thanks