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• x86/dcadec : add ff_lfe_fir0_float_{sse,sse2,avx,fma3}

  5 février 2016, par James Almer

  x86/dcadec : add ff_lfe_fir0_float_sse,sse2,avx,fma3
  Up to 4 times faster on x86_64, 8 times on x86_32 if compiling using x87 fp math.
  Reviewed-by : Ronald S. Bultje <rsbultje@gmail.com>
  
  Signed-off-by : James Almer <jamrial@gmail.com>
  

  • [DH] libavcodec/dcadsp.c
  • [DH] libavcodec/dcadsp.h
  • [DH] libavcodec/x86/Makefile
  • [DH] libavcodec/x86/dcadsp.asm
  • [DH] libavcodec/x86/dcadsp_init.c

• ffmpeg decode video to YUV and damaged pixels

  28 août 2021, par user3807476

  I use this example to decode a mpeg1 video

  


  when decode starts

  


  log (every 3 to 10 frames) :

  


  [mpeg1video @ 0x5626caf74e40] ac-tex damaged at 39 15
[mpeg1video @ 0x5626caf74e40] Warning MVs not available
[mpeg1video @ 0x5626caf74e40] concealing 405 DC, 405 AC, 405 MV errors in P frame


  


  and the result is :

  


  

  


  I tried make rgb from YUV using opencv but the rgb results is same

  


      cv::Size actual_size(frame->width, frame->height);
    cv::Size half_size(frame->width/2, frame->height/2);
    cv::Mat y(actual_size, CV_8UC1, frame->data[0]);
    cv::Mat u(half_size, CV_8UC1, frame->data[1]);
    cv::Mat v(half_size, CV_8UC1, frame->data[2]);

    cv::Mat u_resized, v_resized;
    cv::resize(u, u_resized, actual_size, 0, 0, cv::INTER_NEAREST); //repeat u values 4 times
    cv::resize(v, v_resized, actual_size, 0, 0, cv::INTER_NEAREST); //repeat v values 4 times

    cv::Mat yuv; 
    std::vector yuv_channels = { y, u_resized, v_resized };
    cv::merge(yuv_channels, yuv);

    cv::Mat bgr;
    cv::cvtColor(yuv, bgr, cv::COLOR_YUV2BGR);
    
    cv::imshow("x",bgr);
    cv::waitKey(1000/25);


  


  

  


• How to split multiple audio files by 10 seconds each on OSX ?

  23 juin 2020, par LA_

  Let's say I have 100 audio files and I would like to split each file into several files with 10 seconds length.

  


  I think the following should work :

  


  for i in *.ogg; do
  echo -n $i ...
  ffmpeg -i $i.ogg -ss 0  -t 10 $i_1.ogg
  ffmpeg -i $i.ogg -ss 10 -t 10 $i_2.ogg
  ffmpeg -i $i.ogg -ss 20 -t 10 $i_3.ogg
done


  


  But I don't understand how many times ffmpeg commands should be repeated.