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• Re-sampling H264 video to reduce frame rate while maintaining high image quality

  31 mars 2016, par BrianTheLion

  Here’s the mplayer output for a video of interest :

  br@carina:/tmp$ mplayer foo.mov 
  
  mplayer: Symbol `ff_codec_bmp_tags' has different size in shared object, consider re-linking
  
  MPlayer 1.0rc4-4.5.2 (C) 2000-2010 MPlayer Team
  
  mplayer: could not connect to socket
  
  mplayer: No such file or directory
  
  Failed to open LIRC support. You will not be able to use your remote control.
  
  
  
  Playing foo.mov.
  
  libavformat file format detected.
  
  [lavf] stream 0: video (h264), -vid 0
  
  [lavf] stream 1: audio (aac), -aid 0, -alang eng
  
  VIDEO:  [H264]  1280x720  24bpp  59.940 fps  2494.2 kbps (304.5 kbyte/s)
  
  ==========================================================================
  
  Opening video decoder: [ffmpeg] FFmpeg's libavcodec codec family
  
  Selected video codec: [ffh264] vfm: ffmpeg (FFmpeg H.264)
  
  ==========================================================================
  
  ==========================================================================
  
  Opening audio decoder: [faad] AAC (MPEG2/4 Advanced Audio Coding)
  
  AUDIO: 44100 Hz, 2 ch, s16le, 128.0 kbit/9.07% (ratio: 15999->176400)
  
  Selected audio codec: [faad] afm: faad (FAAD AAC (MPEG-2/MPEG-4 Audio))
  
  ==========================================================================
  
  AO: [pulse] 44100Hz 2ch s16le (2 bytes per sample)
  
  Starting playback...
  
  Movie-Aspect is 1.78:1 - prescaling to correct movie aspect.
  
  VO: [vdpau] 1280x720 => 1280x720 Planar YV12

  I’d like to use ffmpeg, mencoder, or some other command-line video transcoder to re-sample this video to a lower framerate without loss of image quality. That is, each frame should remain as crisp as possible.

  Attempts

  ffmpeg -i foo.mov -r 25 -vcodec copy bar.mov

  • The target frame rate — 25fps — is achieved but individual frames are "blocky."

  mencoder -nosound -ovc copy foo.mov -ofps 25 -o bar.mov

  • Videos are effectively un-viewable.

  Help !

  This seems like a simple enough use case. I’m very surprised that obvious things are not working. Is there something wrong with my approach ?

• lavu/opt : add API for retrieving array-type option values

  25 juillet 2024, par Anton Khirnov

  lavu/opt : add API for retrieving array-type option values
  Previously one could only convert the entire array to a string, not
  
  access individual elements.
  

  • [DH] doc/APIchanges
  • [DH] libavutil/opt.c
  • [DH] libavutil/opt.h
  • [DH] libavutil/tests/opt.c
  • [DH] libavutil/version.h
  • [DH] tests/ref/fate/opt

• Automating FFmpeg/ multi-core support

  23 juillet 2018, par Pablowako

  I need help with FFmpeg/batch. I have a couple of large batches of images (+14000 files each batch, +5 MB each image, .TIFF all of them) and I’m stringing them together into a .mp4 video using FFmpeg.

  The date in the metadata is broken because of the way they’re stored upon creation, so the time and date (T/D) are on the file_name. I need each frame to have its respective T/D (so its File_Name) burnt onto them for accurate measurements (scientific purpose).

  With the help of google and reddit, I’ve managed to semi-automate it like so :

  Master.bat :

  forfiles /p "D:\InputPath" /m "*.TIFF" /S /C "cmd /c C:\SlavePath\slave.bat @file @fname"

  Slave.bat :

  ffmpeg -i "%~1" -vf "drawtext=text=%~2: fontcolor=white: fontsize=30: fontfile='C\:\\FontPath\\OpenSans-Regular.ttf'" "D:\OutputPath\mod_%~1"

  Running Master.bat will output each individual image with the text burnt onto them and change the File_Name to mod_'File_name'.TIFF

  Real example : 2018-06-05—16-00-01.0034.TIFF turns into mod_2018-06-05—16-00-01.0034.TIFF

  The problem is that FFmpeg doesn’t like it when my files have "—" in them ("date—time.miliseconds.TIFF") and doesn’t like the miliseconds either, so I have to change the name of all files "manually" using Bulk Rename Utility (BRU). So, using BRU I rename all files to 00001.TIFF, 00002.TIFF, etc. and FFmpeg likes me again. It works great, but it means I can’t be AFK.

  After that, I have to go back to cmd and manually start the image to video conversion.

  Also, FFmpeg doesn’t seem to be using all cores.

  ---

  I need help finding a way to :

  1. Change master.bat’s output to 00001.TIFF etc. automatically in order of processing (i.e. first to be processed is 1.TIFF, 2nd is 2.TIFF)
  2. Add ffmpeg’s img-to-vid function to the automating system
  3. Get my CPU to use all the cores effectively if possible. 2014/15 posts found on google make it seem as though FFmpeg doesn’t support multi-core or hyperthreading.

  ---

  64bit Windows, i7 7700hq, gtx 1050 4Gb, C : SSD, D : HDD