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• Problems in my sample C code using FFmpeg API

  11 juillet 2019, par Tina J

  I’ve been trying to change an FFmpeg’s example code HERE to call other filters using its C APIs. Say the filter be freezedetect=n=-60dB:d=8 which normally runs like this :

  ffmpeg -i small.mp4 -vf "freezedetect=n=-60dB:d=8" -map 0:v:0 -f null -

  And prints outputs like this :

  [freezedetect @ 0x25b91c0] lavfi.freezedetect.freeze_start: 5.005
  
  [freezedetect @ 0x25b91c0] lavfi.freezedetect.freeze_duration: 2.03537
  
  [freezedetect @ 0x25b91c0] lavfi.freezedetect.freeze_end: 7.04037

  However, the original example displays frames, not these metadata information. How can I change the code to print this metadata information (and not the frames) ?

  I’ve been trying to change the display_frame function below into a display_metadata function. Looks like the frame variable has a metadata dictionary which looks promising, but my attempts failed to use it. I’m also new to C language.

  Original display_frame function :

  static void display_frame(const AVFrame *frame, AVRational time_base)
  
  {
  
      int x, y;
  
      uint8_t *p0, *p;
  
      int64_t delay;
  
  
  
      if (frame->pts != AV_NOPTS_VALUE) {
  
          if (last_pts != AV_NOPTS_VALUE) {
  
              /* sleep roughly the right amount of time;
  
               * usleep is in microseconds, just like AV_TIME_BASE. */
  
              delay = av_rescale_q(frame->pts - last_pts,
  
                                   time_base, AV_TIME_BASE_Q);
  
              if (delay > 0 && delay < 1000000)
  
                  usleep(delay);
  
          }
  
          last_pts = frame->pts;
  
      }
  
  
  
      /* Trivial ASCII grayscale display. */
  
      p0 = frame->data[0];
  
      puts("\033c");
  
      for (y = 0; y < frame->height; y++) {
  
          p = p0;
  
          for (x = 0; x < frame->width; x++)
  
              putchar(" .-+#"[*(p++) / 52]);
  
          putchar('\n');
  
          p0 += frame->linesize[0];
  
      }
  
      fflush(stdout);
  
  }

  My new display_metadata function that needs to be completed :

  static void display_metadata(const AVFrame *frame)
  
  {
  
  
  
  //    printf("%d\n",frame->height);
  
  
  
      AVDictionary* dic = frame->metadata;
  
  
  
      printf("%d\n",*(dic->count));
  
  
  
  //    fflush(stdout);
  
  } 

• Revision 80577dff4b : Revert "Changing webmenc to use libwebm" Temporary revert. Problems with confli

  2 avril 2014, par Paul Wilkins

  Changed Paths :
   Modify /build/make/Makefile

  
   Modify /configure

  
   Modify /examples.mk

  
   Modify /vpxenc.c

  
   Add /webmenc.c

  
   Delete /webmenc.cc

  
   Modify /webmenc.h

  
  
  Revert "Changing webmenc to use libwebm"

  Temporary revert.
  Problems with conflicting definitions of type off_t
  in MSVC builds that need resolving.

  c :\Program Files (x86)\
  Microsoft Visual Studio 9.0\VC\include\wchar.h(479) :
  "error C2371 : 'off_t' : redefinition ; different basic types
  c :\on2experimental\libvpx\tools_common.h(26) :
  see declaration of 'off_t'"

  This reverts commit 92a4c591122fa406a1d7aed834a5283a86d9758a.

  Change-Id : I535e40a18842a92e3e6e0b29e5fba66313010803

• FFmpeg / Avconv video playback problems - black or green tint

  21 octobre 2014, par scottpaterson

  I am using FFmpeg / Avconv to convert a raw video file to a MP4 or AVI. Both FFmpeg and Avconv have the same problem.

  • The output video, both MP4 or AVI, play 100% percent perfect on Linux Mint in the default video player.

  • On Windows in WMP the MP4 plays, but the video is black, and the AVI plays and shows video but it has a green tint. On Windows in Quicktime both formats video is black.

  Here is the command I am using :

   avconv -i /home/scott/Desktop/out.wav -f rawvideo -pix_fmt rgb32 -s:v 540x240 -i 
  
   /home/scott/Desktop/out.raw -c:v libx264 -strict -2 -preset ultrafast -b:v 160k  
  
   /home/scott/Dropbox/code/out.avi

  • I have spent a lot of time messing with the -pix_fmt and trying different pixel format, so far rgb32 returns the best results.

  • I have also tried -sws_flags options such as lanczos+accurate_rnd - but this did not help.

  How can I get this to play the same in all video players ?

  Thanks !