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• How to write the *args of function "avfilter_graph_send_command"(ffmpeg) when there has multiple drawtext targets ?

  19 août 2020, par cube_sun

  I add 2 drawtext on ffmpeg drawtext filter, my filters descr is like this
"drawtext=fontfile=simhei.ttf:fontcolor=#ff00ff@%1.0:fontsize=20:box=1.0:boxcolor=#00ff00@%1.0:x=0:y=0:text='123',drawtext=fontfile=simhei.ttf:fontcolor=#ff00ff@%1.0:fontsize=20:box=1.0:boxcolor=#00ff00@%1.0:x=0:y=200:text='456'", so there have two characters watermark on video.
And this filter supports altering parameters via commands : reinit, so I use function : avfilter_graph_send_command(m_filter_graph, "drawtext", "reinit", m_filters_args, NULL, 0, 0) to modify the watermarks on realtime.(m_filters_args is my *arg variate)
I try snprintf the m_filters_args as
"fontfile=simhei.ttf:fontcolor=#ff00ff@%1.0:fontsize=20:box=1.0:boxcolor=#00ff00@%1.0:x=0:y=10:text='112233',fontfile=simhei.ttf:fontcolor=#ff00ff@%1.0:fontsize=20:box=1.0:boxcolor=#00ff00@%1.0:x=0:y=200:text='445566'", but it doesn't work as I wanted, it can only modify one drawtext, I want they can be both modified, I tried some other ways, but all failed.
can u tell me how to write the *arg or there has other ways to solve the problem.

  


  Any help would be very appreciated !

  


• Framerate vs r vs Filter fps

  7 juillet 2018, par Matt McManis

  I’m trying to better understand FFmpeg framerate.

  Example : If I wanted to convert a 30 fps video to 23.976 fps.

  ---

  What are the differences between :

  Option
  -framerate 24000/1001

  Option
  -r 24000/1001

  Filter
  -vf "fps=24000/1001"

  x265 params
  -x265-params "fps=24000/1001"

  ---

  What I’ve read is :

  -framerate is image sequence fps (input video fps ?)

  -vf "fps=" is encoding fps

  -r is output fps

  However I don’t know if that is correct, or if it changes depending on what order you place them in the options.

  ---

  Questions

  1. -x265-params "fps=" Is it required use it’s own fps param ? Can it not use default options ?

  2. Should multiple Options, Filters ,and Params be combined, or should you only use one ?

  3. Input/Output Framerate

     https://ffmpeg.org/ffmpeg.html#toc-Video-Options

     -r[:stream_specifier] fps (input/output,per-stream)

     If in doubt use -framerate instead of the input option -r.

     Is -r input or output ? How do you specify, by putting before or after the -i ?

• ffmpeg writing the output of the command to a text file doesn't work with C#

  5 février 2021, par Lifshitz

  I am using ffmpeg commands with C# processes. I used a command to change the audio of a video and it was working but I also wanted to write the output to a text file. The new command works from cmd but apparently, it does not work while using a C# process.
The command that does not work with the Process is :

  


  ffmpeg -i videoPath -i audioPath -c:v copy -map 0:v:0 -map 1:a:0 -shortest newVideoPath > textFilePath 2>&1


  


  And the working command is the same without the last part :

  


  ffmpeg -i videoPath -i audioPath -c:v copy -map 0:v:0 -map 1:a:0 -shortest newVideoPath


  


  Here is the C# code :

  


   Process proc = new Process();
 proc.StartInfo.FileName = ffmpegPath;
 proc.StartInfo.RedirectStandardError = true;
 proc.StartInfo.RedirectStandardOutput = true;
 proc.StartInfo.UseShellExecute = false;
 proc.StartInfo.CreateNoWindow = true;
 proc.StartInfo.Arguments = "-i " + videoPath + " -i " + newAudioPath + " -c:v copy" + " -map" + " 0:v:0 " + "-map 1:a:0 " + "-shortest " + newVideoPath + " > " + @"F:\Videos\log.txt"+ " 2>&1";
 proc.EnableRaisingEvents = true;
 proc.Exited += UpdateVideoSource;
 proc.Start();


  


  I checked the arguments over and over again, and looked for missing spaces but nothing worked.
What can be the problem ?