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• ffmpeg determine frame number for fade filter

  16 juin 2016, par Gert Gottschalk

  I am looking for an easy way to set the time points for the fade filter. Particularly for the fade-out at the end. At best would be a time based format. I understand the fade filter works based on frames. But is there a way to change that to time stamp ? Particularly in the end I have a hard time getting the number of the last frame. Some means to tell the fade filter to start the fade 0.5sec before the end would be awesome. Maybe something like :

  -filter:v 'fade=out:-0.5:0.3'

  Read : ’start fade out 0.5sec before end and have fade take 0.3sec. I.e. have 0.2sec of black at the end.

  I would also be OK if this would be in frame number counts.

  My grief right now is that the frame count i.e. reported by ffprobe seems to be somewhat half of what it really is. A fade filter applied on the count provided by ffprobe turn my video to black about half-way through the clip. I’m not sure what I’m missing there.

  Again my primary question is : How to determine the correct frame number for the fade out filter ?

  Thanks,
  Gert

• ffmpeg : how to determine frame rate automatically ?

  25 décembre 2016, par mrgloom

  I use this simple script to convert video to images using ffmpeg, but frame rate is fixed, how can I determine it automatically ?

  FRAME_RATE="30"
  
  SEPARATOR='/'
  
  
  
  
  
  VIDEO_PATH=$1
  
  
  
  VIDEO_BASE_DIR=`dirname $1`
  
  FRAMES_DIR=$VIDEO_BASE_DIR$SEPARATOR"Frames"
  
  rm -rf $FRAMES_DIR
  
  mkdir $FRAMES_DIR
  
  
  
  #Convert video to images
  
  ./ffmpeg -r $FRAME_RATE -i $VIDEO_PATH $FRAMES_DIR$SEPARATOR"image%d.png"

  UPDATE :

  By ffprobe I checked that my 1st video frame rate is 30.
  Also results are the same (339 frames are produced) even I reduce frame rate, so -r option doesn’t work or work in some other way ?

  These command give the same result :

  ./ffmpeg -r 10 -i $VIDEO_PATH $FRAMES_DIR$SEPARATOR"image%d"$EXTENSION
  
  ./ffmpeg -r 30 -i $VIDEO_PATH $FRAMES_DIR$SEPARATOR"image%d"$EXTENSION
  
  ./ffmpeg -i $VIDEO_PATH $FRAMES_DIR$SEPARATOR"image%d"$EXTENSION

  Output :

  ffmpeg version N-63893-gc69defd Copyright (c) 2000-2014 the FFmpeg developers
  
    built on Jul 16 2014 05:38:01 with gcc 4.6 (Debian 4.6.3-1)
  
    configuration: --prefix=/root/ffmpeg-static/64bit --extra-cflags='-I/root/ffmpeg-static/64bit/include -static' --extra-ldflags='-L/root/ffmpeg-static/64bit/lib -static' --extra-libs='-lxml2 -lexpat -lfreetype' --enable-static --disable-shared --disable-ffserver --disable-doc --enable-bzlib --enable-zlib --enable-postproc --enable-runtime-cpudetect --enable-libx264 --enable-gpl --enable-libtheora --enable-libvorbis --enable-libmp3lame --enable-gray --enable-libass --enable-libfreetype --enable-libopenjpeg --enable-libspeex --enable-libvo-aacenc --enable-libvo-amrwbenc --enable-version3 --enable-libvpx
  
    libavutil      52. 89.100 / 52. 89.100
  
    libavcodec     55. 66.101 / 55. 66.101
  
    libavformat    55. 43.100 / 55. 43.100
  
    libavdevice    55. 13.101 / 55. 13.101
  
    libavfilter     4.  8.100 /  4.  8.100
  
    libswscale      2.  6.100 /  2.  6.100
  
    libswresample   0. 19.100 /  0. 19.100
  
    libpostproc    52.  3.100 / 52.  3.100
  
  Input #0, mov,mp4,m4a,3gp,3g2,mj2, from '/home/user/myvideo1.mp4':
  
    Metadata:
  
      major_brand     : mp42
  
      minor_version   : 0
  
      compatible_brands: isommp42
  
      creation_time   : 2016-01-16 05:30:03
  
    Duration: 00:00:11.33, start: 0.000000, bitrate: 4659 kb/s
  
      Stream #0:0(eng): Video: h264 (High) (avc1 / 0x31637661), yuv420p, 640x480, 4539 kb/s, SAR 65536:65536 DAR 4:3, 30 fps, 30 tbr, 90k tbn, 180k tbc (default)
  
      Metadata:
  
        rotate          : 90
  
        creation_time   : 2016-01-16 05:30:03
  
        handler_name    : VideoHandle
  
      Stream #0:1(eng): Audio: aac (mp4a / 0x6134706D), 48000 Hz, stereo, fltp, 127 kb/s (default)
  
      Metadata:
  
        creation_time   : 2016-01-16 05:30:03
  
        handler_name    : SoundHandle
  
  Output #0, image2, to '/home/user/Frames/image%d.png':
  
    Metadata:
  
      major_brand     : mp42
  
      minor_version   : 0
  
      compatible_brands: isommp42
  
      encoder         : Lavf55.43.100
  
      Stream #0:0(eng): Video: png, rgb24, 640x480 [SAR 1:1 DAR 4:3], q=2-31, 200 kb/s, 30 fps, 90k tbn, 30 tbc (default)
  
      Metadata:
  
        rotate          : 90
  
        creation_time   : 2016-01-12 05:38:03
  
        handler_name    : VideoHandle
  
        encoder         : Lavc55.66.101 png
  
  Stream mapping:
  
    Stream #0:0 -> #0:0 (h264 (native) -> png (png))
  
  Press [q] to stop, [?] for help
  
  frame=  339 fps= 68 q=0.0 Lsize=N/A time=00:00:11.30 bitrate=N/A    
  
  video:195852kB audio:0kB subtitle:0kB other streams:0kB global headers:0kB muxing overhead: unknown

• How to use FFMPEG to determine actual FPS of an RTMP stream

  18 mai 2016, par Dexter1759

  I’m trying to determine the best way to analyse any RTMP stream. I’m currently settled upon the FFMPEG suite of tools, however, I find myself in need of help before I drive myself crazy.

  I’m trying to validate a stream, I’ve been asked to determine the following :

  • Can I connect to the stream ? - this can be done easily with FFProbe
  • Is there video ? (i.e. it’s not all black) - I’ve managed to build a POC so don’t think this will be a problem.
  • Is there audio ? (i.e. not all silent) - Again, don’t think this is a problem based on my POC.
  • Actual FPS - here’s where I get stuck because the meta data shows 25fps and that’s what FFTools return.

  However, using FFPlay I can see the odd message of "no frame !" and would prefer to calculate the actual FPS for comparison.

  Any help/advice with this toolset would be useful.

  (Note : I’ve also had other issues/questions with this toolset but have started with this one rather than dump a list here)

  Many thanks.

  EDIT - Forgot to mention the stream is of a live feed so things like "duration" and "nb_frames" return "N/A"