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• How are ARM GPUs supported by Video display/decoding/encoding Programs ?

  7 juillet 2020, par John Allard

  I often see ARM-based chips advertising onboard GPUs, like the RPI3 that came with "Broadcom VideoCore IV @ 250 MHz" and the OdroidC2 that comes with a "Mali-450 GPU". These chips advertise stuff like "Decode 4k/30FPS, Encode 1080p,30FPS" as the capabilities of the GPU for encoding and decoding videos.

  


  My question is this - how does a program like Kodi, VLC, or FFMPEG come to make use of these GPUs for actual encoding and decoding ? When I do research on how to make use of the Mali-450 GPU, for example, I find some esoteric and poorly documented C-examples of sending compressed frames to the GPU and getting decoded frames back. If I were to use a device like the OdroidC2 and install VLC on it, how does VLC make use of the GPU ? Did someone have to write logic into VLC to use the specific encoding/decoding API exposed by the Mali GPU in order to use it or do these GPUs follow some sort of consistent API that is exposed by all GPUs and VLC/Kodi can just program against this system API ?

  


  The reason I ask this question is that VLC and Kodi tend to support these GPUs out of the Box, but a very popular program like FFMPEG that prides itself on supporting as many codecs and accelerators as possible has no support for decoding and encoding with the Mali GPU series. Why would VLC/Kodi support encoding/decoding and not FFMPEG ? Why do these manufacturers claim wild decoding and encoding support if these GPUs are difficult to program against and one must use their custom esoteric APIs instead of something like libavcodec ?

  


  I hope my question makes sense, I guess what I'm curious about is that GPUs on most systems whether it be the Intel HD Graphics, Nvidia cards, AMD cards, etc seem to be used automatically by most video players but when it comes to using something like FFMPEG against these devices the process becomes much more process and you need to custom compile the build and give special flags to use the device as intended. Is there something I'm missing here ? Is VLC programmed to make use of all of these different type of GPUs ? And why, in that case, does FFMEPG not support Mali GPUs out of the Box ?

  


• Playing audio file using libavcodec and libao

  21 août 2013, par sarah john

  Myself trying to play an audio file using libavcodec in qt5 .While trying to play i am unable to play the the file.
  while decoding the file using av_read_frame()
  audioStream->index=0
  and packet.stream_index is some higher nos .so avcodec_decode_audio4() is not getting executed.Why is it so ?
  I am getting output as
  My output

  ---

  File Opend

  Input #0, ogg, from '/home/tel/Downloads/desktop-login.ogg':
  
  Duration: 00:00:07.72, start: 0.000000, bitrate: 108 kb/s
  
  Stream #0:0: Audio: vorbis, 44100 Hz, stereo, fltp, 112 kb/s
  
  audioStream 0x88b3f20
  
  Stream id: 0
  
  Codec ptr: 0x88b4100
  
  Codec Opened
  
  DRIVER ID 1
  
  Sample format 3
  
  Sample format:AV_SAMPLE_FMT_FLT 32
  
  Sample format channels 0
  
  Sample format rate 0
  
  Sample format  4
  
  buffersize  192008

  This is my program. My output is also given below.Please help me in solving this.

  for(i=0; i < container->nb_streams; i++){
  
  
  
      if(container->streams[i]->codec->codec_type==AVMEDIA_TYPE_AUDIO){
  
           stream_id=i;
  
           audioStream=container->streams[i];
  
  
  
           qWarning() <<"audioStream"<streams[stream_id]->codec;
  
  qWarning() <<"Codec ptr:"<< ctx;
  
  AVCodec *codec=avcodec_find_decoder(ctx->codec_id);
  
  if(codec==NULL){
  
          die("cannot find codec!");
  
  }
  
  
  
  if(avcodec_open2(ctx,codec,NULL)<0){
  
          die("Codec cannot be opended!");
  
  }
  
  else
  
          qWarning()<<"Codec Opened";
  
  
  
  
  
          ao_initialize();
  
          driver = ao_default_driver_id();
  
          qWarning()<<"DRIVER ID" <sample_fmt;
  
          qWarning()<<"Sample format"<channels;
  
     qWarning()<<"Sample format channels"<sample_rate;
  
    qWarning()<<"Sample format rate"<codec;
  
    while(av_read_frame(container,&packet)>=0)
  
    {
  
  
  
          if(packet.stream_index==audioStream->index){
  
          len=avcodec_decode_audio4(ctx,frame,&frameFinished,&packet);
  
          qWarning()<<"Enterd if loop";
  
  
  
          if(frameFinished){
  
              qWarning()<<"PLAYING";
  
              ao_play(audio_device, (char*)frame->extended_data[0],frame->linesize[0] );
  
          }
  
    }

• Using Intel QSV in WSL2

  26 janvier 2023, par heebin

  I want to use Intel QSV in WSL2.

  


  Based on the experience of using QSV on a native Ubuntu PC, I installed the same library, but it doesn't work.

  


  ex) ffmpeg, libva, vainfo, intel Media SDK, gmmlib, media-driver ...

  


  My CPU supports QSV, but I can't initialize it.

  


  In vainfo it works like this :

  


  $ ls /dev/dri
card0 renderD128

$ sudo vainfo
Trying display: wayland
error: XDG_RUNTIME_DIR not set in the environment.
Trying display: x11
libva info: VA-API version 1.16.0
libva info: User environment variable requested driver 'iHD'
libva info: Trying to open /usr/lib/x86_64-linux-gnu/dri/iHD_drv_video.so
libva info: Found init function __vaDriverInit_1_14
DRM_IOCTL_I915_GEM_APERTURE failed: Invalid argument
Assuming 131072kB available aperture size.
May lead to reduced performance or incorrect rendering.
get chip id failed: -1 [22]
param: 4, val: 0
libva error: /usr/lib/x86_64-linux-gnu/dri/iHD_drv_video.so init failed
libva info: va_openDriver() returns 18
vaInitialize failed with error code 18 (invalid parameter),exit


  


  I want WSL to be initialized properly so I can use it in C.