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• Screen capture (video screencast) with FFMPEG with very low FPS

  20 septembre 2023, par jesusda

  I recently changed PCs, I went from having an Intel Core i5 4460 with integrated graphics card to a Xeon E5 2678 v3 with AMD RADEON RX 550 graphics.

  


  On paper, the new PC is on the order of 3 to 7 times more powerful than the old one and I can attest that this is the case in daily use, video and image editing etc. The advantage of having so many cores and threads available is palpable. In terms of games I haven't tried it because I'm not really a gamer and the few games I use are the typical free ones that come with Debian and some emulators that, honestly, already worked fine with the old PC.

  


  However there is one task that brings me head over heels for its terrible performance : video screen capture.

  


  With my old PC I was able to capture at over 60 fps at full screen while doing any task I needed to record.

  


  Even with my lenovo thinkpad x230 I am able to capture screen at over 80fps with total fluency.

  


  The command I have always used is :

  


  ffmpeg  -f x11grab -draw_mouse 1 -framerate 60 -video_size 1920x1200 -i :0.0+1680,0  -qscale 0 -pix_fmt yuv420p -c:v libx264 -preset medium -qp 0 -q:v 1 -s 1920x1200 -f matroska -threads 4 video.mkv


  


  notes :

  


  -video_size 1920x1200 -i :0.0+1680,0 y -s 1920x1200 are the dimensions and position of the region to capture (my right monitor).

  


  Notice that I even used -preset medium and software encoding, so I got very good quality even with that parameter setting and without ever going below 60 fps.

  


  What happens to me now ?

  


  The equipment is unable to capture more than 20 fps which makes any video invalid, with frame drops and not even reach 30fps, which would be the minimum required.

  


  In addition, it is quite noticeable the decrease in responsiveness of the PC as soon as I launch the command. That is, all that fluidity and smoothness that is appreciated when working normally, disappears and even moving a window from one side to another is rough and stumbling.

  


  I have tried with different parameters of ffmpeg, to capture raw, without encoding.

  


  I have tried saving the resulting video directly to RAM disk in order to avoid the possible bottleneck of writing to disk. It doesn't affect it at all.

  


  So, does anyone have any suggestions as to at least where I can dig further to find a solution to the problem ?

  


  Additional data, in case it helps :

  


  $ → inxi
CPU: 12-Core Intel Xeon E5-2678 v3 (-MT MCP-)
speed/min/max: 1201/1200/3300 MHz Kernel: 5.10.0-0.bpo.4-amd64 x86_64
Up: 1d 6h 55m Mem: 6427.6/32012.4 MiB (20.1%)
Storage: 13.76 TiB (55.9% used) Procs: 433 Shell: bash 5.0.18 inxi: 3.0.32


$ → ffmpeg -v
ffmpeg version 4.1.6 Copyright (c) 2000-2020 the FFmpeg developers
  built with gcc 8 (Debian 8.3.0-6)
  configuration: --disable-decoder=amrnb --disable-decoder=libopenjpeg --disable-libopencv --disable-outdev=sdl2 --disable-podpages --disable-sndio --disable-stripping --enable-libaom --enable-avfilter --enable-avresample --enable-gcrypt --disable-gnutls --enable-openssl --enable-gpl --enable-libass --enable-libbluray --enable-libbs2b --enable-libcaca --enable-libcdio --enable-libcodec2 --enable-libfdk-aac --enable-libfontconfig --enable-libfreetype --enable-libfribidi --enable-libgme --enable-libgsm --enable-libilbc --enable-libkvazaar --enable-libmp3lame --enable-libopencore-amrnb --enable-libopencore-amrwb --enable-libopenh264 --enable-libopenjpeg --enable-libopenmpt --enable-libopus --enable-libpulse --enable-librubberband --enable-libshine --enable-libsnappy --enable-libsoxr --enable-libspeex --enable-libtesseract --enable-libtheora --enable-libvidstab --enable-libvo-amrwbenc --enable-libvorbis --enable-libvpx --enable-libx265 --enable-libzimg --enable-libxvid --enable-libzvbi --enable-nonfree --enable-opencl --enable-opengl --enable-postproc --enable-pthreads --enable-shared --enable-version3 --enable-libwebp --incdir=/usr/include/x86_64-linux-gnu --libdir=/usr/lib/x86_64-linux-gnu --prefix=/usr --toolchain=hardened --enable-frei0r --enable-chromaprint --enable-libx264 --enable-libiec61883 --enable-libdc1394 --enable-vaapi --enable-libmfx --enable-libvmaf --disable-altivec --shlibdir=/usr/lib/x86_64-linux-gnu
  libavutil      56. 22.100 / 56. 22.100
  libavcodec     58. 35.100 / 58. 35.100
  libavformat    58. 20.100 / 58. 20.100
  libavdevice    58.  5.100 / 58.  5.100
  libavfilter     7. 40.101 /  7. 40.101
  libavresample   4.  0.  0 /  4.  0.  0
  libswscale      5.  3.100 /  5.  3.100
  libswresample   3.  3.100 /  3.  3.100
  libpostproc    55.  3.100 / 55.  3.100


  


  I have the free amdgpu drivers (not amdgpu-pro), but I activated OpenCL just in case.

  


  I followed this tutorial.

  


  $ → glxinfo | grep OpenGL
OpenGL vendor string: AMD
OpenGL renderer string: Radeon RX550/550 Series (POLARIS12, DRM 3.40.0, 5.10.0-0.bpo.4-amd64, LLVM 11.0.1)
OpenGL core profile version string: 4.6 (Core Profile) Mesa 20.3.4
OpenGL core profile shading language version string: 4.60
OpenGL core profile context flags: (none)
OpenGL core profile profile mask: core profile
OpenGL core profile extensions:
OpenGL version string: 4.6 (Compatibility Profile) Mesa 20.3.4
OpenGL shading language version string: 4.60
OpenGL context flags: (none)
OpenGL profile mask: compatibility profile
OpenGL extensions:
OpenGL ES profile version string: OpenGL ES 3.2 Mesa 20.3.4
OpenGL ES profile shading language version string: OpenGL ES GLSL ES 3.20
OpenGL ES profile extensions:





$ → clinfo
Number of platforms                               1
  Platform Name                                   Clover
  Platform Vendor                                 Mesa
  Platform Version                                OpenCL 1.1 Mesa 20.3.4
  Platform Profile                                FULL_PROFILE
  Platform Extensions                             cl_khr_icd
  Platform Extensions function suffix             MESA

  Platform Name                                   Clover
Number of devices                                 1
  Device Name                                     Radeon RX550/550 Series (POLARIS12, DRM 3.40.0, 5.10.0-0.bpo.4-amd64, LLVM 11.0.1)
  Device Vendor                                   AMD
  Device Vendor ID                                0x1002
  Device Version                                  OpenCL 1.1 Mesa 20.3.4
  Driver Version                                  20.3.4
  Device OpenCL C Version                         OpenCL C 1.1
  Device Type                                     GPU
  Device Profile                                  FULL_PROFILE
  Device Available                                Yes
  Compiler Available                              Yes
  Max compute units                               8
  Max clock frequency                             1183MHz
  Max work item dimensions                        3
  Max work item sizes                             256x256x256
  Max work group size                             256
  Preferred work group size multiple              64
  Preferred / native vector sizes
    char                                                16 / 16
    short                                                8 / 8
    int                                                  4 / 4
    long                                                 2 / 2
    half                                                 0 / 0        (n/a)
    float                                                4 / 4
    double                                               2 / 2        (cl_khr_fp64)
  Half-precision Floating-point support           (n/a)
  Single-precision Floating-point support         (core)
    Denormals                                     No
    Infinity and NANs                             Yes
    Round to nearest                              Yes
    Round to zero                                 No
    Round to infinity                             No
    IEEE754-2008 fused multiply-add               No
    Support is emulated in software               No
    Correctly-rounded divide and sqrt operations  No
  Double-precision Floating-point support         (cl_khr_fp64)
    Denormals                                     Yes
    Infinity and NANs                             Yes
    Round to nearest                              Yes
    Round to zero                                 Yes
    Round to infinity                             Yes
    IEEE754-2008 fused multiply-add               Yes
    Support is emulated in software               No
  Address bits                                    64, Little-Endian
  Global memory size                              3221225472 (3GiB)
  Error Correction support                        No
  Max memory allocation                           1717986918 (1.6GiB)
  Unified memory for Host and Device              No
  Minimum alignment for any data type             128 bytes
  Alignment of base address                       32768 bits (4096 bytes)
  Global Memory cache type                        None
  Image support                                   No
  Local memory type                               Local
  Local memory size                               32768 (32KiB)
  Max number of constant args                     16
  Max constant buffer size                        67108864 (64MiB)
  Max size of kernel argument                     1024
  Queue properties
    Out-of-order execution                        No
    Profiling                                     Yes
  Profiling timer resolution                      0ns
  Execution capabilities
    Run OpenCL kernels                            Yes
    Run native kernels                            No
  Device Extensions cl_khr_byte_addressable_store cl_khr_global_int32_base_atomics cl_khr_global_int32_extended_atomics cl_khr_local_int32_base_atomics cl_khr_local_int32_extended_atomics cl_khr_int64_base_atomics cl_khr_int64_extended_atomics cl_khr_fp64

NULL platform behavior
  clGetPlatformInfo(NULL, CL_PLATFORM_NAME, ...)  Clover
  clGetDeviceIDs(NULL, CL_DEVICE_TYPE_ALL, ...)   Success [MESA]
  clCreateContext(NULL, ...) [default]            Success [MESA]
  clCreateContextFromType(NULL, CL_DEVICE_TYPE_DEFAULT)  Success (1)
    Platform Name                                 Clover
    Device Name                                   Radeon RX550/550 Series (POLARIS12, DRM 3.40.0, 5.10.0-0.bpo.4-amd64, LLVM 11.0.1)
  clCreateContextFromType(NULL, CL_DEVICE_TYPE_CPU)  No devices found in platform
  clCreateContextFromType(NULL, CL_DEVICE_TYPE_GPU)  Success (1)
    Platform Name                                 Clover
    Device Name                                   Radeon RX550/550 Series (POLARIS12, DRM 3.40.0, 5.10.0-0.bpo.4-amd64, LLVM 11.0.1)
  clCreateContextFromType(NULL, CL_DEVICE_TYPE_ACCELERATOR)  No devices found in platform
  clCreateContextFromType(NULL, CL_DEVICE_TYPE_CUSTOM)  No devices found in platform
  clCreateContextFromType(NULL, CL_DEVICE_TYPE_ALL)  Success (1)
    Platform Name                                 Clover
    Device Name                                   Radeon RX550/550 Series (POLARIS12, DRM 3.40.0, 5.10.0-0.bpo.4-amd64, LLVM 11.0.1)

ICD loader properties
  ICD loader Name                                 OpenCL ICD Loader
  ICD loader Vendor                               OCL Icd free software
  ICD loader Version                              2.2.12
  ICD loader Profile                              OpenCL 2.2


  


  This would not be a tearing problem, as no tearing is visible when playing videos and the TearFree driver policy is enabled.

  


  $ → xrandr --verbose | grep TearFree
    TearFree: on
    TearFree: on
    TearFree: on


  


• FFMpeg - Trimming out the video after removing duplicate frames

  29 avril 2021, par MarianD

  I removed many duplicate frames from video (and completely removed audio) by this command

  



  ffmpeg -i scene.mkv -vf mpdecimate,setpts=N/FRAME_RATE/TB -map:v 0  scene3.mp4


  



  (by an Mulvya's answer, thanks again).

  



  The resulting video is OK but the total duration will not change - the last frame of original video is frozen to fill the remaining time (when playing back the video).

  



  Is there some way to trim the video so that it will finish at this last frame ?

  


• Anomalie #3234 (Nouveau) : Upload gros fichiers

  19 juin 2014, par Eric Camus

  Bonjour,

  Avec SPIP 3.0.16 sans plugins (sur serveur WIMP et LAMP).

  Si on demande le téléchargement d’un poids de fichiers (un ou plusieurs) supérieur à POST_MAX_SIZE on se retrouve avec la page d’édition de l’article dans lequel on était dans le cadre de téléchargement : c’est super chouette artistiquement mais c’est tout (cf P.J.).

  Pour résoudre ce problème, j’ai placé dans ’mes_options.php’ le code suivant qui permet d’afficher un texte dans le cadre :
  

  // capturer un formulaire post en surcharge !!!
  if($_SERVER[’REQUEST_METHOD’]==’POST’ and strlen($_SERVER[’CONTENT_TYPE’])>0 and
      substr($_SERVER[’CONTENT_TYPE’],0,19)==’multipart/form-data’ and
      $_SERVER[’CONTENT_LENGTH’]>inigetoctets(’post_max_size’)) 
      // on est en hors quota donc erreur
          echo ’
  
  Erreur de chargement :
  
              
  le poids total des fichiers dépasse la limite autorisée (’.ini_get(’post_max_size’).
  
              ’o).
  Pour recommencer, veuillez recharger cette page.
  
  ’ ;
  
          exit ;
  
  
  function inigetoctets($var) 
  
      $val=trim(ini_get($var)) ;
  
      if($val !=’’) 
  
          $last=strtolower($val[strlen($val)-1]) ;
  
      
  
      else 
  
          $last=’’ ;
  
      
  
      switch($last)  // The ’G’ modifier is available since PHP 5.1.0
  
          case ’g’ :
  
              $val*=1024 ;
  
          case ’m’ :
  
              $val*=1024 ;
  
          case ’k’ :
  
              $val*=1024 ;
  
      
  
      return $val ;
  
  
  

  Comme il me semble que les formulaires de téléchargement sont dans des cadres ’java’ cela ne doit pas poser d’autres problèmes ?
  Si c’est le cas, il faudrait envisager de placer un code de ce type quelque part dans le core de SPIP pour pallier à tout formulaire de téléchargement.

  Nota : si taille des données POST > POST_MAX_SIZE alors les variables $_POST et $_FILES sont vides.