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• Gnuplot how to set a variable to standard-input if not passed

  27 août 2020, par DDS

  I have a gnuplot script (plot.script) that is invoked like

  


  C:> ffmpeg -i '.\my_awesome_audio_file.wav' -filter_complex aformat=channel_layouts=mono -acodec pcm_s16le -ar 4000 -f data - | gnuplot -e "fileout='plot';fileformat='png';wid=500;" .\plot.script        


  


  Now I'd want to default filein variable to stdin if it is not passed as argument. This because I want to be able to call this script as a 1-liner command with ffmpeg data generation and also as step-by-step procedure

  


  My idea was to use

  


  if(!exists('filein')){
filein = '-';
}


  


  but this throws warning: Skipping data file with no valid points

  


  if i print the variable datafile I got - (I expected something like stdin).

  


  this is the plot.script script :

  


  
if(!exists('filein')){
    filein = '-';
    }

if (!exists("hei")){
    hei = 4444;
    }
if (!exists("wid")){
    wid = 5555;
    }
if(!exists("fileformat")){
     fileformat = 'png';
     }
if(!exists("fileout")){
     fileout = 'risultato';
   }
   
fileout = fileout . '.' . fileformat;
   
if(!exists("dataformat")){
    dataformat = '%int16';
    }
if(fileformat eq 'png'){
  set terminal png transparent size larghezza,altezza;
  
  }else{
  set terminal fileformat size wid,hei;
  }
  set output fileout;
  unset key;
  unset tics;
  unset border;
  set lmargin 0;
  set rmargin 0;
  set tmargin 0;
  set bmargin 0;


print filein;
plot filein binary filetype=bin format=dataformat endian=little array=1:0 with lines linecolor "0x009900";


  


  But I also want to call this command-by-command :
generate the data-file :

  


  c:> ffmpeg -i '.\my_awesome_audio_file.wav' -filter_complex aformat=channel_layouts=mono -acodec pcm_s16le -ar 4000 -f data audio.dat


  


  plot the data :

  


  c:> gnuplot -e "filein='audio.dat';fileout='plot';fileformat='png';wid=500;" .\plot.script


  


• Converting videos to flv using ffmpeg

  6 janvier 2012, par user703526

  In my c# application, i am writing code for converting any video format to flv format. For this FFMPEG is used.

  Some times an exceptions is occuring like :

  Attempted to read or write protected memory. This is often an indication that other memory is corrupt

  Below is my code from where the exception throwing,

      IntPtr pFormatContext;
  
      FFmpeg.av_register_all();
  
  
  
      int ret;
  
      ret = FFmpeg.av_open_input_file(out pFormatContext, this.Filename, IntPtr.Zero, 0, IntPtr.Zero);
  
  
  
      if (ret < 0)
  
      {
  
          Trace.WriteLine("couldn't open input file");
  
  
  
          FFmpeg.av_free_static();
  
          return;
  
      }
  
  
  
  
  
      try
  
      {
  
          ret = FFmpeg.av_find_stream_info(pFormatContext);
  
  
  
          if (ret < 0)
  
          {
  
              Trace.WriteLine("couldnt find stream informaion");
  
              FFmpeg.av_close_input_file(pFormatContext);
  
              FFmpeg.av_free_static();
  
              return;
  
          }
  
  
  
  
  
          FFmpeg.AVFormatContext formatContext = (FFmpeg.AVFormatContext)Marshal.PtrToStructure(pFormatContext, typeof(FFmpeg.AVFormatContext));
  
  
  
          Duration = formatContext.duration / FFmpeg.AV_TIME_BASE;
  
  
  
          for (int i = 0; i < formatContext.nb_streams; ++i)
  
          {
  
              FFmpeg.AVStream stream = (FFmpeg.AVStream)Marshal.PtrToStructure(formatContext.streams[i], typeof(FFmpeg.AVStream));
  
              FFmpeg.AVCodecContext codec = (FFmpeg.AVCodecContext)Marshal.PtrToStructure(stream.codec, typeof(FFmpeg.AVCodecContext));
  
  
  
              if (codec.codec_type == FFmpeg.CodecType.CODEC_TYPE_VIDEO)
  
              {
  
                  Height = codec.height;
  
                  Width = codec.width;
  
  
  
                          Type = FileType.flv;
  
                          MimeType = "video/x-flv";
  
  
  
              }
  
  
  
          }
  
      }
  
      catch (Exception ex)
  
      {
  
          Trace.WriteLine("FFMpeg failed to understand the file");
  
      }
  
  
  
      FFmpeg.av_close_input_file(pFormatContext);
  
      FFmpeg.av_free_static();
  
  }

  And from the above code this ret = FFmpeg.av_find_stream_info(pFormatContext); line throws memory corrupt exception.
  Please help me to solve this issue.

• Encoding videos with mixed aspect ratios in hevc [closed]

  25 octobre 2020, par bader515

  I have a huge library of movies, TV Shows, Anime, and Cartoons (about 16tb sorted by plex on my NAS).

  


  Most of them are encoded in h.264, and each video has a different aspect ratio (1920x1080,1280x720...etc).

  


  Is there a way to re-encode them using any tool to hevc with the same aspect ratio and bit per pixel ?

  


  I have already tried using this command using ffmpeg, but the result is a bigger size video (with the sd videos) :

  


  pushd "%2"
SET paths=paths.txt
SET /A ffmpeg_qv=24
if EXIST %paths% (
for /f "tokens=*" %%a in (%paths%) do (
    echo Changing to directory %%a
    pushd "%%a"
    CALL :ffmpeg
    )
) else (
CALL :ffmpeg
)
pause
EXIT /B %ERRORLEVEL%
  :ffmpeg
    for /R %%A in (*.mp4, *.avi, *.mov, *.wmv, *.ts, *.m2ts, *.mkv, *.mts) do 
(
        echo Processing "%%A"
    ffmpeg -hwaccel auto -i "%%A" -pix_fmt yuv420p -map 0:v -map 0:a -map_metadata 0 -c:v hevc_nvenc -rc constqp -qp %ffmpeg_qv% -b:v 0K -c:a aac -b:a 384k -movflags +faststart -movflags use_metadata_tags "%%A_CRF%ffmpeg_qv%_HEVC.mp4"
    echo Processed %%A
)
GOTO :EOF