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• Rendering video streaming in android

  16 avril 2013, par user1568549

  I've successfully cross-compiled a c++ streaming library to the ICS platform

  This library contains a sample player that uses sdl library to render the resulting decoded streams and libav for decoding that i've also succeeded to cross compile(libav ... classes) .Then, i 've made the necessary jni classes and tested it log tags it seems that everything is fine but now i want to show the result on the screen(show the real streaming not just log messages)

  I am searching for the easiest way to render my video-stream (just to be sure that everything works fine)

  Am i obliged to cross-compile the SDL library too ? Is it possible ? If yes is there any good tutorial ?

  Is there any other solution to render directly FFmpeg decoded frames ?

• Inconsistent behavior when placing adjacent video overlays

  24 juillet 2023, par abingham

  This script uses ffmpeg to overlay a red [1] and blue [2] stream atop a yellow [0] stream. The intent is that the red stream will be exactly adjacent to the blue stream ; at frame 1731 the output video should transition immediately from pure red to pure blue :

  


  # These values result in a blank frame where the videos join at around 58s
LENGTH=1800
SPLIT_AT=1731

# These values work just fine.
# LENGTH=1800
# SPLIT_AT=2

ffmpeg \
-f lavfi -r 30 -i "color=c=yellow:s=1920x1080" \
-f lavfi -r 30 -i "color=c=990000:s=1920x1080" \
-f lavfi -r 30 -i "color=c=000099:s=1920x1080" \
-filter_complex \
"[1]concat=n=1[red_concat];"\
"[red_concat]tpad=start=0[red_pad];"\
"[0][red_pad]overlay=enable=between(n\,0\,$SPLIT_AT):eof_action=repeat[red_overlay];"\
"[2]concat=n=1[blue_concat];"\
"[blue_concat]tpad=start=$SPLIT_AT[blue_pad];"\
"[red_overlay][blue_pad]overlay=enable=between(n\,$SPLIT_AT\,$LENGTH):eof_action=repeat[blue_overlay];"\
"[blue_overlay]trim=end_frame=$LENGTH[full];" \
 -map "[full]" video.mp4 -y


  


  However, what I see is that there is a single black frame between the pure red and pure blue. This black seems to be coming from the frames that tpad adds.

  


  What I don't understand is why I'm seeing that black frame. As far as I can tell, my uses of tpad and overlay/enable-between should produce a seamless transition from red to blue. And indeed, if I change the SPLIT_AT value to almost anything else I get exactly that ; the value 1731 is "special" in some way.

  


  Can anyone explain what's going on ? Maybe more importantly, can anyone reproduce this problem ?

  


  My first thought was that I've got some form of fencepost error in how I'm using tpad or enable-between. However, that doesn't explain why the script works for most values but not 1731. This difference in results feels like there's a rounding error somewhere, but since I'm dealing purely in terms of integer frame numbers, I don't see how I could be introducing them.

  


  A few notes :

  


  


  • This is a drastically reduced example from a larger video compositing system. Things like the use of concat may appear unnecessary, but they're representative of what the larger system is doing.

    


  


  • I'm using ffmpeg-6.0 installed via homebrew on an M1 macbook

    


  


  


• Anomalie #3079 (Nouveau) : articles syndiqués toujours présents en partie publique même sans syndi...

  28 octobre 2013, par Johan .

  Je créé un site syndiqué n°N. Je le publie :

  • spip.php ?siteN affiche bien la liste des articles syndiqués.

  Je modifie le site en décochant l’option de syndication :

  • ecrire/ ?exec=site&id_syndic=N n’affiche plus les articles syndiqués : ok
  • spip.php ?siteN affiche toujours la liste des articles syndiqués : problème

  Lancé les crons dans la liste des travaux n’a aucun effet.

  Solution rustine : resyndiquer le site, Effacer tous les articles syndiqués, « dé-syndiquer » le site.

  J’ai constaté ceci sur un 3.0.10 (en prod) et vient de le reproduire aussi en SPIP 3.1.0-dev SVN [20894] (sans plugins).