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• vframes option ignored in ffmpeg ?

  25 mars 2016, par cooper

  I have a directory that contains 2001 PNG files. I can convert all of the frames to an mp4 video using ffmpeg and the following command :

  ffmpeg -framerate 60 -start_number 0 \
  
  -i pic.comp2.%07d.png -c:v libx264 -r 30 \
  
  -pix_fmt yuv420p input1ia.mp4

  This works fine. However, I am creating a more complicated application that needs to read only the first 1020 files in the directory (specifically 0 thru 1019). Some googling around led me to the -vframes option. My problem is — it seems to get ignored or at least interpreted differently than I expect.

  My modified command looks like :

  ffmpeg -framerate 60 -start_number 0 \
  
  -i pic.comp2.%07d.png -vframes 1020 -c:v libx264 
  
  -r 30 -pix_fmt yuv420p input1.mp4

  It seems like many other people doing the same thing as me do not encounter this issue. So I did some more digging. I tried changing vframes from 1020 to -vframes 20, and this seemed to work properly. So now I am thinking it might be some kind of mismatch between -framerate and -r ?

  The full resultant video is 33 sec long... which makes sense mathematically.

   1 sec
  
   ---------   x  2001 frames = 33.35 seconds
  
   60 frames

  That’s why I thought that specifying 1/2 of the PNGs as the ’end point’ would result in a video of the first 16-17 seconds. But I always get the full length video from using the -vframes option.

  I assume my input to -vframes must be incorrect mathematically, since a small number of frames seems to work. However, I do not understand why.

  The most educated guess I can seem to make is that it is reading the PNGs as 60fps (-framerate), but the -r makes the output video 30fps or something ? However, then I would assume that the full output video would not be 33 seconds long.

• Metadata is not showing ffmpeg C++

  18 août 2015, par Kaidul Islam

  I am muxing h264 encoded video data and PCM g711 encoded audio data into a .mov media container. I am trying to write metadata on header but the metadata is not showing when I go to file->right click->properties->details on windows and likewise in Ubuntu. This is my code -

  // Instead of creating new AVDictionary object, I also tried following way
  
  // stated here: http://stackoverflow.com/questions/17024192/how-to-set-header-metadata-to-encoded-video 
  
  // but no luck
  
  AVDictionary* pMetaData = m_pFormatCtx->metadata;
  
  av_dict_set(&pMetaData, "title", "Cloud Recording", 0);
  
  av_dict_set(&pMetaData, "artist", "Foobar", 0);
  
  av_dict_set(&pMetaData, "copyright", "Foobar", 0);
  
  av_dict_set(&pMetaData, "filename", m_sFilename.c_str(), 0);
  
  time_t now = time(0);
  
  struct tm tStruct = *localtime(&now);
  
  char date[100];
  
  strftime(date, sizeof(date), "%c", &tStruct); // i.e. Thu Aug 23 14:55:02 2001
  
  av_dict_set(&pMetaData, "date", date, 0);
  
  av_dict_set(&pMetaData, "creation_time", date, 0);
  
  av_dict_set(&pMetaData, "comment", "This video has been created using Eyeball MSDK", 0);
  
  
  
  // ....................
  
  // .................
  
  
  
  /* write the stream header, if any */
  
  int ret = avformat_write_header(m_pFormatCtx, &pMetaData);

  I also tried to see if the file contains any metadata using mediainfo and exiftools in linux. Also I tried ffmpeg -i output.mov but no metadata is shown.

  Whats the problem ? Is the flags value 0 in av_dict_set okay ? DO I need to set different flags for different platform (windows/linux) ?

  I saw this link and it stated that for windows, I have to use id3v2_version 3 and -write_id3v1 1 to make metadata working. If so, how can I do this in C++ ?

• Problems accessing codecs with ggplot and gganimate

  19 décembre 2016, par noLongerRandom

  Using gganimate. Can’t figure out how to properly access functionality of ffmpeg, specifically I want to change the codec I’m using in the video file I’m outputting.

  # load packages
  
  library(ggplot)
  
  library(animation)
  
  library(gganimate)
  
  
  
  # Here's my data.frame
  
  myDf <- data.frame(
  
      year = c(1962, 1963, 1964, 1965, 1966, 1967, 1968, 1969, 1970, 1971, 1972, 1973, 1974, 1975, 1976, 1977, 1978, 1979, 1980, 1981, 1982, 1983, 1984, 1985, 1986, 1987, 1988, 1989, 1990, 1991, 1992, 1993, 1994, 1995, 1996, 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2011, 2012, 2013, 2014), 
  
      bottom50 = c(0.195, 0.191, 0.187, 0.192, 0.196, 0.205, 0.207, 0.210, 0.209, 0.204, 0.203, 0.204, 0.205, 0.203, 0.202, 0.200, 0.200, 0.201, 0.199, 0.195, 0.190, 0.183, 0.179, 0.179, 0.177, 0.172, 0.169, 0.169, 0.168, 0.166, 0.158, 0.159, 0.158, 0.154, 0.151, 0.148, 0.149, 0.148, 0.146, 0.149, 0.148, 0.145, 0.142, 0.138, 0.135, 0.137, 0.137, 0.136, 0.130, 0.127, 0.123, 0.127, 0.125), top1 = c(0.126, 0.127, 0.129, 0.128, 0.126, 0.123, 0.122, 0.115, 0.110, 0.111, 0.111, 0.109, 0.106, 0.105, 0.105, 0.107, 0.108, 0.111, 0.107, 0.110, 0.112, 0.115, 0.125, 0.125, 0.122, 0.133, 0.149, 0.145, 0.145, 0.139, 0.150, 0.146, 0.147, 0.153, 0.160, 0.166, 0.169, 0.177, 0.183, 0.173, 0.171, 0.172, 0.183, 0.194, 0.201, 0.199, 0.195, 0.185, 0.198, 0.196, 0.208, 0.196, 0.202)
  
  )
  
  
  
  #Basic plot
  
  p <- ggplot(myDf, aes(x = year, y = bottom50, frame = year)) + 
  
      geom_line(color = "dodgerblue") + 
  
      geom_line(aes(y = top1), color = "darkred")

  The non-animated version gets me what I want :

  

  And I get an animation version output to video with :

  gganimate(p, interval = .1, title_frame = FALSE, "income.mp4")

  That’s fine, but I want to change some the output parameters, specifically : alter the dimensions, the frame rate, and use a different codec.

  # change some of the options
  
  ani.options(ani.height = 1080, ani.width = 1920, 
  
              interval = 0.04166667, other.opts = "-vcodec qtrle -f mov")
  
  # re-animate
  
  gganimate(p, title_frame = FALSE, "income.mov")

  That gives me the following error :

  Error in animation_saver(saver, filename) : 
  
    Don't know how to save animation of type mov

  I’m using ’.mov’ as my file extension because I’m trying to change to the Animation codec (so it’s no longer a .mp4 wrapper). I’ve got ffmpeg installed, so this is probably a syntax issue. But the documentation isn’t very clear here ; gganimate doesn’t have any documentation on changing codecs (or outputting any video besides an mp4), and the animation package is light on specifics as well.