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• Failed to hard-ware accelerate video decoding via Tesla P40

  20 mai 2018, par Potemkin

  While I am writing a surveillance video recognition demo, I find it is much slower to simply play a video in the server(Xeon E5-2680 2.4GHz, Tesla P40) than in my laptop(i7-8550 1.8GHz, Intel UHD Graphics 620).

  I use DXVA-Checker to see the video decoder device, and notice that my laptop use the GPU for decoding, but the server use no GPU for the job. Then I check ’nvidia-smi’, and it shows all of GPUs are running in TCC driver model, not WDDM driver model. And I cannot turn it to WDDM because nvidia-smi says it is not supported.

  The video play demo is written via OPENCV, in which the video decoding part is from ffmpeg. The server runs in Windows-server-2012, and my laptop is on Windows 10.

  The question is how can I get the server decoding videos with GPUs, and is this the reason for the slowness or there is something else ?

• Using ffmpeg, the function av_find_input_format("avfoundation") return null

  28 avril 2019, par guojing

  I run this code in iPad mini 4 (Model A1538), iOS 11.2.6

  Try to record audio by FFmpeg.

  av_register_all();
  
  avcodec_register_all();
  
  avdevice_register_all();
  
  
  
  AVFormatContext *pFormatCtx = avformat_alloc_context();
  
  AVDictionary* options = NULL;
  
  av_dict_set(&options,"list_devices","true",0);
  
  AVInputFormat *iformat = av_find_input_format("avfoundation");
  
  printf("==AVFoundation Device Info===\n");
  
  avformat_open_input(&pFormatCtx,"",iformat,&options);
  
  printf("=============================\n");
  
  
  
  if(avformat_open_input(&pFormatCtx,"0",iformat,NULL)!=0){
  
      printf("Couldn't open input stream.\n");
  
      return;
  
  }

  pFormatCtx = NULL, and iformat = NULL.

  Why should this happen, did I missed anything to set ?

• Error inclunding in FFMPEG project on a Mac using clang

  3 juillet 2018, par benwiz

  I’m having trouble running the remuxing.c example code. I get the following error. I have confirmed that the files can be found in /usr/local/include. I am running macOS Sierra 10.12.6.

  $ cc -v playground/remuxing.c
  
  Apple LLVM version 9.0.0 (clang-900.0.39.2)
  
  Target: x86_64-apple-darwin16.7.0
  
  Thread model: posix
  
  InstalledDir: /Library/Developer/CommandLineTools/usr/bin
  
   "/Library/Developer/CommandLineTools/usr/bin/clang" -cc1 -triple x86_64-apple-macosx10.12.0 -Wdeprecat
  
  ed-objc-isa-usage -Werror=deprecated-objc-isa-usage -emit-obj -mrelax-all -disable-free -disable-llvm-v
  
  erifier -discard-value-names -main-file-name remuxing.c -mrelocation-model pic -pic-level 2 -mthread-mo
  
  del posix -mdisable-fp-elim -fno-strict-return -masm-verbose -munwind-tables -target-cpu penryn -target
  
  -linker-version 305 -v -dwarf-column-info -debugger-tuning=lldb -resource-dir /Library/Developer/Comman
  
  dLineTools/usr/lib/clang/9.0.0 -fdebug-compilation-dir /Users/myuser/github/personal/synthesthesi
  
  a -ferror-limit 19 -fmessage-length 103 -stack-protector 1 -fblocks -fobjc-runtime=macosx-10.12.0 -fenc
  
  ode-extended-block-signature -fmax-type-align=16 -fdiagnostics-show-option -fcolor-diagnostics -o /var/
  
  folders/8s/2xc3v8dd7zz2c2trymzybvd534bnhg/T/remuxing-819223.o -x c playground/remuxing.c
  
  clang -cc1 version 9.0.0 (clang-900.0.39.2) default target x86_64-apple-darwin16.7.0
  
  #include "..." search starts here:
  
  #include <...> search starts here:
  
   /usr/local/include
  
   /Library/Developer/CommandLineTools/usr/lib/clang/9.0.0/include
  
   /Library/Developer/CommandLineTools/usr/include
  
   /usr/include
  
   /System/Library/Frameworks (framework directory)
  
   /Library/Frameworks (framework directory)
  
  End of search list.
  
   "/Library/Developer/CommandLineTools/usr/bin/ld" -demangle -lto_library /Library/Developer/CommandLineTools/usr/lib/libLTO.dylib -no_deduplicate -dynamic -arch x86_64 -macosx_version_min 10.12.0 -o a.out /var/folders/8s/2xc3v8dd7zz2c2trymzybvd534bnhg/T/remuxing-819223.o -lSystem /Library/Developer/CommandLineTools/usr/lib/clang/9.0.0/lib/darwin/libclang_rt.osx.a
  
  Undefined symbols for architecture x86_64:
  
    "_av_dump_format", referenced from:
  
        _main in remuxing-819223.o
  
    "_av_freep", referenced from:
  
        _main in remuxing-819223.o
  
    "_av_interleaved_write_frame", referenced from:
  
        _main in remuxing-819223.o
  
    "_av_mallocz_array", referenced from:
  
        _main in remuxing-819223.o
  
    "_av_packet_unref", referenced from:
  
        _main in remuxing-819223.o
  
    "_av_read_frame", referenced from:
  
        _main in remuxing-819223.o
  
    "_av_rescale_q", referenced from:
  
        _main in remuxing-819223.o
  
    "_av_rescale_q_rnd", referenced from:
  
        _main in remuxing-819223.o
  
    "_av_strerror", referenced from:
  
        _av_make_error_string in remuxing-819223.o
  
    "_av_write_trailer", referenced from:
  
        _main in remuxing-819223.o
  
    "_avcodec_parameters_copy", referenced from:
  
        _main in remuxing-819223.o
  
    "_avformat_alloc_output_context2", referenced from:
  
        _main in remuxing-819223.o
  
    "_avformat_close_input", referenced from:
  
        _main in remuxing-819223.o
  
    "_avformat_find_stream_info", referenced from:
  
        _main in remuxing-819223.o
  
    "_avformat_free_context", referenced from:
  
        _main in remuxing-819223.o
  
    "_avformat_new_stream", referenced from:
  
        _main in remuxing-819223.o
  
    "_avformat_open_input", referenced from:
  
        _main in remuxing-819223.o
  
    "_avformat_write_header", referenced from:
  
        _main in remuxing-819223.o
  
    "_avio_closep", referenced from:
  
        _main in remuxing-819223.o
  
    "_avio_open", referenced from:
  
        _main in remuxing-819223.o
  
  ld: symbol(s) not found for architecture x86_64
  
  clang: error: linker command failed with exit code 1 (use -v to see invocation)