Recherche avancée

Sur d’autres sites (11147)

• How to get output from ffmpeg process in c#

  13 juillet 2018, par Anirudha Gupta

  In the code I written in WPF, I run some filter in FFmpeg, If I run the command in terminal (PowerShell or cmd prompt) It will give me information line by line what’s going on.

  I am calling the process from C# code and it’s work fine. The problem I have with my code is actually I am not able to get any output from the process I run.

  I have tried some answers from StackOverflow for FFmpeg process. I see 2 opportunities in my code. I can either fix it by Timer approach or secondly hook an event to OutputDataReceived.

  I tried OutputDataReceived event, My code never got it worked. I tried Timer Approach but still, it’s not hitting my code. Please check the code below

          _process = new Process
  
          {
  
              StartInfo = new ProcessStartInfo
  
              {
  
                  FileName = ffmpeg,
  
                  Arguments = arguments,
  
                  UseShellExecute = false,
  
                  RedirectStandardOutput = true,
  
                  RedirectStandardError = true,
  
                  CreateNoWindow = true,
  
              },
  
              EnableRaisingEvents = true
  
          };
  
  
  
          _process.OutputDataReceived += Proc_OutputDataReceived;
  
  
  
          _process.Exited += (a, b) =>
  
          {
  
              System.Threading.Tasks.Task.Run(() =>
  
              {
  
                  System.Threading.Tasks.Task.Delay(5000);
  
                  System.IO.File.Delete(newName);
  
              });
  
  
  
              //System.IO.File.Delete()
  
          };
  
  
  
          _process.Start();
  
          _timer = new Timer();
  
          _timer.Interval = 500;
  
          _timer.Start();
  
          _timer.Tick += Timer_Tick;
  
      }
  
  
  
  
  
      private void Timer_Tick(object sender, EventArgs e)
  
      {
  
          while (_process.StandardOutput.EndOfStream)
  
          {
  
             string line = _process.StandardOutput.ReadLine();
  
          }
  
          // Check the process.
  
  
  
      }

• compat/w32pthreads : change pthread_t into pointer to malloced struct

  12 décembre 2024, par Anton Khirnov

  compat/w32pthreads : change pthread_t into pointer to malloced struct
  pthread_t is currently defined as a struct, which gets placed into
  
  caller's memory and filled by pthread_create() (which accepts a
  
  pthread_t*).
  The problem with this approach is that pthread_join() accepts pthread_t
  
  itself rather than a pointer to it, so it gets a _copy_ of this
  
  structure. This causes non-deterministic failures of pthread_join() to
  
  produce the correct return value - depending on whether the thread
  
  already finished before pthread_join() is called (and thus the copy
  
  contains the correct value), or not (then it contains 0).
  Change the definition of pthread_t into a pointer to a struct, that gets
  
  malloced by pthread_create() and freed by pthread_join().
  Fixes random failures of fate-ffmpeg-error-rate-fail on Windows after
  
  433cf391f58210432be907d817654929a66e80ba.
  See also [1] for an alternative approach that does not require dynamic
  
  allocation, but relies on an assumption that the pthread_t value
  
  remains in a fixed memory location.
  [1] https://code.videolan.org/videolan/x264/-/commit/23829dd2b2c909855481f46cc884b3c25d92c2d7
  Reviewed-By : Martin Storsjö <martin@martin.st>
  

  • [DH] compat/w32pthreads.h

• FFMPEG - C API - GIF creation

  6 mars 2020, par Vuwox

  I have an image processing pipeline, and I have images in memory that I convert into AVFrame and I try to create a GIF with those.

  I started from this topic and I just replaced the video decoder part with a conversion of my image in memory to an AVFrame.

  This work pretty well, but I have issue with the GIF framerate.

  Into the init_filters(...) method, I don’t understand the time_base and pixel_aspect variables of the argument structure :

      snprintf(args, sizeof(args),
  
           "video_size=%dx%d:pix_fmt=%d:time_base=%d/%d:pixel_aspect=%d/%d",
  
           width, height, in_fmt, time_base.num, time_base.den,
  
           pixel_aspect.num, pixel_aspect.den);

  I would like to have a FPS=12, so should I define them as follow ?

  AVRational time_base = AVRational{1, 12};
  
  AVRational pixel_aspect= AVRational{1, 1}; 

  Next, in the loop where I feed the frame to the filter buffer (for the palettegen), I also have an options that I don’t understand, what the AVFrame->pts refers to ?

      // palettegen need a whole stream, just add frame to buffer.
  
      ret = av_buffersrc_add_frame_flags(buffersrc_ctx, picture_rgb24, AV_BUFFERSRC_FLAG_KEEP_REF);
  
      if (ret < 0) {
  
          av_log(nullptr, AV_LOG_ERROR, "error add frame to buffer source %s\n", av_make_error_string(msg_v2, MSG_LEN, ret));
  
      }
  
  
  
      picture_rgb24->pts += 1; // HERE

  As far as I understand, its supposed to be the timestamp of the frame, in my case, I have a GIF, should I increase by 1 every time ? or 1000ms / 12 frame = 83.33 ms ? Im not sure, I tried to found the information but no luck so far.

  There is also the init_muxer(...) method where its possible to set the time_base of the output (GIF) :

      o_codec_ctx->time_base = AVRational{1, 12};

  So I get a bit confused with all the place where we have to set the framerate.

  Right now, the GIF is well generated (with the palette) in memory using FFMPEG C API, the only problem is that the GIF is way too fast and not at the right framerate.