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• FFMPEG Dash with tiles of thumbnail images

  31 juillet 2020, par martyn Gilbert

  As of DASH-IF IOP version 4.2, section 6.2.6 defines the notion of image-based tracks in DASH :
https://dashif.org/docs/DASH-IF-IOP-v4.3.pdf.

  



  This is the ability to have an adaption set made up of mime type images that themselves are a strip of low resolution thumbnails. 
A player will use these thumbnails when the user hovers their mouse over the video timeline and get a 
preview of the the frame at that approximate timecode.

  



  Theo player website has a page dedicated to this function for playback :
https://www.theoplayer.com/blog/in-stream-thumbnail-support-dvr-dash-streams

  



  I need to generate a dash stream (not live) using ffmpeg that also contains these thumbnails. 
I already have an ffmpeg command that will generate the film strip of jpgs which outputs a thumbnail every 5 seconds of input video and joins 5 of these together in a single jpg :

  



  ffmpeg -i INPUT -q:v 20 -vf "select=not(mod(n\,125)),scale=480:270,tile=5x1" -vsync vfr output%d.jpg

  



  and the mpeg dash itself :

  



  ffmpeg -i INPUT -y -map 0 -acodec aac -ac 2 -ar 48000 -s 960x540 -vcodec libx264 -f dash -preset veryfast -b:v:2 1500k -seg_duration 2 output.mpd

  



  But I cannot find a way in ffmpeg to include the thumbnails in the dash mpd file.

  


• Optimizing Adaptive Streaming with FFMPEG

  25 octobre 2018, par Ramesh Navi

  I am working on a video on demand website, I am using laravel 5.7, FFMPEG and DASH player from (dashif.org). Got some questions.

  Extracting audio like :

  ffmpeg -i original.mp4 -vn -acodec libvorbis -ab 128k -dash 1 my_audio.webm

  Converting video like :

  ffmpeg -i original.mp4 -c:v libvpx-vp9 -keyint_min 150 \
  
  -g 150 -tile-columns 4 -frame-parallel 1  -f webm -dash 1 \
  
  -an -vf scale=160:190 -b:v 250k -dash 1 video_160x90_250k.webm \
  
  -an -vf scale=320:180 -b:v 500k -dash 1 video_320x180_500k.webm \
  
  -an -vf scale=640:360 -b:v 750k -dash 1 video_640x360_750k.webm \
  
  -an -vf scale=1280:720 -b:v 1500k -dash 1 video_1280x720_1500k.webm

  Creating manifest like :

  ffmpeg \
  
  -f webm_dash_manifest -i video_160x90_250k.webm \
  
  -f webm_dash_manifest -i video_320x180_500k.webm \
  
  -f webm_dash_manifest -i video_640x360_750k.webm \
  
  -f webm_dash_manifest -i video_1280x720_1500k.webm \
  
  -f webm_dash_manifest -i my_audio.webm \
  
  -c copy \
  
  -map 0 -map 1 -map 2 -map 3 -map 4 \
  
  -f webm_dash_manifest \
  
  -adaptation_sets "id=0,streams=0,1,2,3 id=1,streams=4" \
  
  my_video_manifest.mpd

  Now the problems :

  1. Video conversion takes a lot of time on the latest i5 8gb
     think-pad running Ubuntu 18. 4minute mp4 took more than 30minute. 10minute, 720p MP4 took forever, had to kill the process. Is
     that normal ? Any idea to optimize ?
  2. Need to find out original
     video’s dimension so that I can avoid dimension conversion more than
     the original. ffprob looks fine in command but produces too much of
     information than required, is there any simple function ?
  3. Converted webm file is bigger in size than original mp4, original
     mp4 of 720p was 33MB, but 640p webm is 76MB. Is that normal or
     something wrong ?

  Any suggestions to optimize the process are welcome.

• sh file imagemagick modification

  16 avril 2013, par Love

  I have an .sh script that generate thumbnail sprites' images from video. The below codes in the script will output the image similar this : http://s1-www.ltvimg.com/cdn/farfuture/7NO-FuBvaWJK_v34cJrAmHi6L3ywPn1YtImQNzXgTic/mtime:1362848979/sites/default/files/tooltipthumbs-sprite.jpg

  For now, the dimension of each thumbnail is 108x60, maximum 25 thumbnails(5x5) per image and per image dimension is 540x300. The thumbnail is capture every second of the video, which mean if i have a 75 seconds of video, it will output 75 thumbnails with 3 images.

  What i need now, i want the script generate only 1 image per video. Which mean 75 thumbnails all in 1 image. What i need to change on the below codes to make this works ?

  mogrify -verbose -resize 108x60 -gravity center -quality 100 -background black 
  
  -extent 108x60 MONTAGE*.png
  
  
  
  numimages=`ls -1 *.png | wc -l | cut -d " " -f1`
  
  
  
  montage -verbose MONTAGE*.png -geometry +0+0 -tile 5x5 -quality 100 -background 
  
  black "$basename"-%04d.jpg
  
  
  
  mogrify -verbose -resize 540x300 -gravity north -extent 540x300 -quality 100 
  
  -background black "$basename"-*.jpg