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• ffmpeg status & quality / cuda (CPU/GPU)

  18 avril 2015, par cocco

  ffmpeg am i doing it right ?

  So much time has passed since i use ffmpeg to convert clips on my home web server, now that mp4 (h264 & aac) is the current overall standard (works on every console, smartphone, smartTV, pc) i decided to convert my old clips from various digital cameras to to this new container/codecs.

  1. less space & the same quality.
  2. compatibility
  3. support for tags (subler for mac)

  after some research i opted for ffmpeg because of various reasons

  1. commandline (i made my simple web interface with default settings wich i execute with php’s exec)
  2. the quality/size amount

  I read that many expensive video conversion softwares are not able to handle low bitrate videos properly. I also tested some of them and personally i could not find the proper export settings or i was not impressed by the results... some had fixed default export setings, most had a lower video quality at the same filesize. ffmpeg allows me to set the -crf (18-24 usually) and -preset (veryslow, fast..) witch allows me to reduce the filesize drastically mantaining the same
  visible quality.

  Said that i’m using the preset at veryslow.(there is also placebo but the final video file is only 1% smaller in size).

  And here is the command i use

  ffmpeg
  
  -y //overwrite the file if it exists
  
  
  
  -i INPUTFILE // replace with the input file
  
  
  
  -metadata title=THETITLE // set a nice title, visible on modern devices
  
  -metadata date=THEDATE // set a nice title, visible on modern devices
  
  
  
  -c:v libx264 // use the h264 codec
  
   -crf 21 // try different numbers between 18-26
  
   -preset veryslow // placebo,slow,fast,ultrafast==big file 
  
   -tune film // tune it a little
  
   -pix_fmt yuv420p // preferred on most modern devices
  
   -profile:v main // preferred on most modern devices
  
   -level 3.1 // preferred on most modern devices 
  
   -refs 4 // preferred on most modern devices
  
  
  
  -c:a libfdk_aac // use aac
  
   -metadata:s:a language=eng // set a language, visible on modern devices 
  
   -b:a 128k // audio bitrate 128k is like mp3 192k
  
   -ar 48000 // 44100 ... whatever
  
   -ac 2 // audiochannels
  
   -movflags +faststart //move the metadata in the front of the video so it loads faster
  
  
  
  OUTPUTFILE

  some camcorder clips with m2ts already have the avc/h264 compatible codec so i just copy the stream.
  some have the ac3/dolby sorround audio. I convert the audio but keep the ac3 as second audio track mapping the ffmpeg streams.this allows me to watch the mp4 on browsers and mobile devices but i’m able to keep the surround sound to playback on some tv’s, advanced media players or devices like apple tv.

  not that i’m not happy with the speed (using quad core’s) but i recently read again about cuda opencl and there is also the simple fact that i’m not using other converters than ffmpeg since alot of time.

  Is ffmpeg (with the setting i use) a good converter to keep the same video quality than the source reducing the space occupied by and average of 30-40% ?

  Is GPU conversion really that bad (cuda .. testing a gtx970) ?
  it would be nice to add some more speed to the conversions by using both the gpu and the cpu..but for my understanding they cannot work together ??? and using only gpu is a drastical quality loss...cpu si more precise, gpu is faster in calculation are too imprecise from what i read.. so expensive softwares use cuda only for preview purpose... right ?

  Is ffmpeg or another software compatible with CPU+GPU encoding ?
  i really don’t remember where, but i read that the ffmpeg is not a good videoconverter.

  i’m really happy with the size/quality, i gained an average of 30% in space with no visible quality loss. With some extra parameters i can adjust some really old analog videos that are deinterlaced in a really bad way.

  maybe i could gain more size/quality with another software ???

  note : i like ffmpeg.it’s free and it has commandline so i can create my own interface with php html & js and use it on various machines without the need to install it in every device i use. i uplad the idevice clips directly to the ffmpeg server.

  btw. : explain the downvotes...

  EDIT :

  @talonmies ...cuda tag removed :

  http://www.nvidia.com/object/cuda_home_new.html

  CUDA® is a parallel computing platform and programming model invented
  by NVIDIA. It enables dramatic increases in computing performance by
  harnessing the power of the graphics processing unit (GPU). With
  millions of CUDA-enabled GPUs sold to date, software developers,
  scientists and researchers are finding broad-ranging uses for GPU
  computing with CUDA. Here are a few examples : - See more at :
  http://www.nvidia.com/object/cuda_home_new.html#sthash.dEYaqae7.dpuf

  isn’t cuda the programming model that a theoretical ffmpeg library should support to handle GPU encoding on nvidia cards like the gtx 970 ?? like the badaboom software http://www.geforce.com/games-applications/pc-applications/badaboom-media-converter.

• Compiling x264 on a Mac : "No working C compiler found" and "arm-linux-androideabi-gcc : command not found"

  29 novembre 2014, par Xavi Gil

  I am trying to compile the x264 library for Android, following this post.

  I have cloned the x264 project git clone git://git.videolan.org/x264.git and tried to compile with the following configuration :

  NDK=~/development/android-ndk-r10c    
  
  TOOLCHAIN=$NDK/toolchains/arm-linux-androideabi-4.6/prebuilt/linux-x86_64
  
  PLATFORM=$NDK/platforms/android-21/arch-arm
  
  
  
  ./configure \
  
  --cross-prefix=$TOOLCHAIN/bin/arm-linux-androideabi- \
  
  --sysroot=$PLATFORM \
  
  --host=arm-linux \
  
  --enable-pic \
  
  --enable-static \
  
  --disable-cli

  The problem is that I get a No working C compiler found. error.

  The conftest.log output :

  $ cat conftest.log 
  
  ./configure: line 153: arm-linux-androideabi-gcc: command not found

  But the arm-linux-androideabi-gcc is the toolchain’s bin folder !!

  Looking at this other question it looks like for some reason, even though the file exists, since it is a 64bit Mac, it won’t execute the arm-linux-androideabi-gcc file and will return this weird error and log.

  ---

  I am in a Mac OS X 10.10 and I have installed the XCode Command Line Tools :

  $ xcode-select -p
  
  /Applications/Xcode.app/Contents/Developer

  GCC version :

  $ gcc --version
  
  Configured with: --prefix=/Applications/Xcode.app/Contents/Developer/usr --with-gxx-include-dir=/usr/include/c++/4.2.1
  
  Apple LLVM version 6.0 (clang-600.0.54) (based on LLVM 3.5svn)
  
  Target: x86_64-apple-darwin14.0.0
  
  Thread model: posix

  ---

  Can anyone tell me how to fix this please ?

• Display YUV420P video using OpenGLES on iPhone

  25 décembre 2014, par user3487978

  I am writing an app displaying YUV420p video using ffmpeg library on iPhone, every thing works fine, but the OpenGL color is a little strange, see picture, the bellow image is displaying using AVPicture in RGB format, above is using AVPicture in YUV format.
  any ideas ?

  my shader

  varying highp vec2 varTexcoord;
  
  uniform sampler2D SamplerY;
  
  uniform sampler2D SamplerUV;
  
  void main (void)
  
  {
  
      mediump vec3 yuv;
  
      lowp vec3 rgb;
  
      yuv.x = texture2D(SamplerY, varTexcoord).r;
  
      yuv.yz = texture2D(SamplerUV, varTexcoord).rg - vec2(0.5, 0.5);
  
      // Using BT.709 which is the standard for HDTV
  
      rgb = mat3(      1,       1,      1,
  
                  0, -.18732, 1.8556,
  
                  1.57481, -.46813,      0) * yuv;
  
      gl_FragColor = vec4(rgb,1.0);
  
  }

  Renderer :

  glActiveTexture(GL_TEXTURE0);
  
  glTexImage2D(GL_TEXTURE_2D,
  
               0,
  
               GL_LUMINANCE,
  
               (GLsizei)model.width,
  
               (GLsizei)model.height,
  
               0,
  
               GL_LUMINANCE,
  
               GL_UNSIGNED_BYTE,
  
               [model.y bytes]);
  
  glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
  
  glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
  
  glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
  
  glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
  
  
  
  glActiveTexture(GL_TEXTURE1);
  
  glTexImage2D(GL_TEXTURE_2D,
  
               0,
  
               GL_LUMINANCE,
  
               (GLsizei)model.width/2,
  
               (GLsizei)model.height/2,
  
               0,
  
               GL_LUMINANCE,
  
               GL_UNSIGNED_BYTE,
  
               [model.uv bytes]);
  
  glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
  
  glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
  
  glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
  
  glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);