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• Avoiding ffmpeg audio drift for live dash output

  22 mai 2021, par mdale

  Have people experienced playback drift with ffmpeg based dash segment generation ? For example :

  


  ffmpeg -threads 2 -re -fflags +genpts -stream_loop -1 -i AVSyncTest.mp4 \
-af "aresample=async=1:min_hard_comp=0.100000:first_pts=0" \
-c:v:0 libx264 \
-pix_fmt:0 yuv420p \
-preset:0 medium \
-a53cc:0 1 \
-nal-hrd:0 cbr \
-x264opts:0 scenecut=-1:rc_lookahead=0 -b:v:0 5000k -bufsize:0 500k \
-force_key_frames:0 "expr:gte(t,n_forced*2)" \
-bf:0 8 \
-r 30 \
-c:a:0 aac  -ar 48000 \
-b:a:1 96k  \
-f tee -map 0:v \
-map 0:a "[f=dash:media_seg_name='chunk-stream_\$RepresentationID\$-\$Number%05d\$.mp4':init_seg_name='init-stream_\$RepresentationID\$.mp4':seg_duration=2:utc_timing_url=https\\\://time.akamai.com\\?iso:remove_at_exit=0:use_timeline=0:http_user_agent=ffmpeg_encoder.0:streaming=1:index_correction=1:timeout=1:dash_segment_type=mp4:method=PUT:http_persistent=1:adaptation_sets='id=0,streams=v\:0 id=1,streams=a' ]http://localhost:5000/out.mpd "


  


  After a bit of playback it starts audio starts to drift. Analysis of the moof (with tools like mp4box) shows 1024 sample size with 93 Moofs with Moof->traf->default_sample_duration=1024 at 48000 sample rate giving segment duration of 1.984 seconds with every 3rd segment or so with 92 Moofs with duration of 1.962 … While each segment starts aligned ( if you reset playback you get alignment) it drifts against continuous playback.

  


  Other examples like Akamai’s public stream. show 94 Moofs or 2.005 duration with every 3rd segment or so at the 1.984 duration. (what one would want)

  


  Akamai’s (presumably ffmepg based) stream is averaging out to the 2s target where the above ffmpeg command is not …

  


• Anomalie #4729 (Nouveau) : problème d’affichage dans la colone date

  13 avril 2021, par Franck D

  Hello, j’ai essayer en local mais aussi chez ovh en php 8 et cela fait pareil.
  spip SPIP 3.3.0-dev GIT [master : 235be9bc] sans même un article dedans

  Installation d’un spip tout neuf vierge avec uniquement gd2 et les miniatures d’aciver et le plug simplog que j’ai eu via svp
  J’ai fait l’ajout d’un fichier mes_options après l’installation avec dedans :
  define(’_NO_CACHE’, -1) ;
  define(’_INTERDIRE_COMPACTE_HEAD_ECRIRE’, true) ;
  error_reporting(E_ALL^E_NOTICE) ;
  ini_set ("display_errors", "On") ;
  define(’SPIP_ERREUR_REPORT’,E_ALL) ;
  $GLOBALS[’taille_des_logs’] = 500 ;
  define(’_MAX_LOG’, 500000) ;
  define(’_LOG_FILELINE’,true) ;
  define(’_LOG_FILTRE_GRAVITE’,8) ;
  define(’_DEBUG_SLOW_QUERIES’, true) ;
  define(’_BOUCLE_PROFILER’, 5000) ;

  Je viens de me rendre compte qu’il y a un problème, si je clique pour un affichage à deux ans, pour un tableau (voir copie d’écran)

• Continuous remultiplexing of two MPEG-TS multicasts into a single MPEG-TS multicast in the face of upstream errors

  29 mars 2021, par Anonymous Coward

  I remultiplex PIDs from two incoming multicasts into a single TS using something like below :

  


  ffmpeg -i udp://239.1.1.1:5000 -i udp://239.1.1.2:5000 -map 0:v -map 0:a -map 1:a -codec copy -f mpegts udp://239.1.1.3:5000


  


  This works well when the multicasts are stable, but occasionally one of the multicasts will disappear for a short period of time. In this case, the output stops and the remaining input buffer start to fill as it is not being drained, sometimes overrunning the circular buffer. When the failed input returns, the backed-up buffer is not drained, so there is an ongoing offset between the inputs.

  


  Is it possible to configure ffmpeg in such a way that the output continues, just without the missing PID ? eg so the video and first audio continue, but the second audio is not present for the period that input is missing.

  


  Thanks in advance !