Recherche avancée

Sur d’autres sites (10479)

• GOP size does not correlate with actual latency

  28 mai 2019, par Alex

  As far as I know, GOP size should correlate with observable video delay (latency). For example, if GOP size is 2, then delay in video should be near two seconds and so on, at least with CBR. But, when I set GOP size to 2, publish stream to ingest server, consume this stream and measure latency, it is between 0.8-1.2 seconds, not 2+ seconds as excepted. Increasing GOP size leads to same results : with GOP 4 latency is near 2.5 seconds, not 4 seconds.

  How I measure this latency : stream working stopwatch from web-camera using OBS to ingest server and calculate difference between stopwatch value and value displayed in stream consumed from ingest. For greater measurement accuracy, I make a photo with stopwatch and actual image from ingest in one field of view.

  My OBS settings is here :

  

  Can you suggest, why do I get such results and how relevant is my statement about correlation between GOP size and video latency ? Maybe, H264 settings like "zerolatency" makes some magic ?

  Thanks.

• Anomalie #4342 (Fermé) : Erreur 1071 de mysql : Specified key was too long ; max key length is 1000 ...

  26 mai 2019

  Bonjour,

  Après avoir configuré MariaDB pour être en UTF8MB4, je n’ai pas pu installer un plugin (comme il y a aussi un bug SVP, je vais faire un autre ticket spécifique).
  Pour être précis, un table du plugin n’a pas été créée et sql.log contient :
  

  2019-05-25 16:23:59 78.205.175.37 (pid 16091) :Pri:ERREUR : Erreur 1071 de mysql : Specified key was too long ; max key length is 1000 bytes
  in ecrire/base/create.php L73 [sql_create(),creer_ou_upgrader_table(),alterer_base(),maj_tables(),serie_alter(),maj_while(),maj_plugin(),referer_spam_upgrade(),spip_plugin_install(),plugins_installer_dist(),installer_plugin(),do_install(),do_action(),one_action(),action_actionner_dist(),traiter_appels_actions()]
  CREATE  TABLE IF NOT EXISTS `mutu_pro2spipf126`.spip_referer_spam (
          date DATE NOT NULL,
          referer VARCHAR (255) ,
          PRIMARY KEY (referer)) ENGINE=MyISAM
  

  La documentation sur ce sujet est abondante.
  Ceci m’a semblé un bon résumé du problème : https://stackoverflow.com/questions/6172798/mysql-varchar255-utf8-is-too-long-for-key-but-max-length-is-1000-bytes
  Et la solution générale consiste à faire un index de seulement 191 : https://dev.mysql.com/doc/refman/5.7/en/charset-unicode-conversion.html :
  

  In an InnoDB table that uses COMPACT or REDUNDANT row format, these column and index definitions are legal :
  col1 VARCHAR(500) CHARACTER SET utf8, INDEX (col1(255))
  To use utf8mb4 instead, the index must be smaller :
  
  col1 VARCHAR(500) CHARACTER SET utf8mb4, INDEX (col1(191))
  

• FFMPEG shows bitrate=N/A and doesn't send anything

  20 mai 2019, par Mehul Jain

  I am trying to relay an stream from one rtsp url to another without recoding using this command :

  ffmpeg
 -rtsp_transport tcp
 -fflags nobuffer
 -re
 -i rtsp://xxx.xxx.xxx.xxx:554/[stream_name]
 -vcodec copy
 -an
 -f rtsp rtsp://yyy.yyy.yyy.yyy/[new_stream_name]

  But FFMPEG doesn’t stream anything and stats shows bitrate=N/A

  This is the exact output that i get :

  ffmpeg version 4.1.3-static https://johnvansickle.com/ffmpeg/    Copyright (c) 2000-2019 the FFmpeg developers
 built with gcc 6.3.0 (Debian 6.3.0-18+deb9u1) 20170516
 configuration: --enable-gpl --enable-version3 --enable-static --disable-debug --disable-ffplay --disable-indev=sndio --disable-outdev=sndio --cc=gcc-6 --enable-fontconfig --enable-frei0r --enable-gnutls --enable-gmp --enable-gray --enable-libfribidi --enable-libass --enable-libfreetype --enable-libmp3lame --enable-libopencore-amrnb --enable-libopencore-amrwb --enable-librubberband --enable-libsoxr --enable-libspeex --enable-libvorbis --enable-libopus --enable-libtheora --enable-libvidstab --enable-libvo-amrwbenc --enable-libvpx --enable-libwebp --enable-libx264 --enable-libxml2 --enable-libxvid --enable-libzimg
 libavutil      56. 22.100 / 56. 22.100
 libavcodec     58. 35.100 / 58. 35.100
 libavformat    58. 20.100 / 58. 20.100
 libavdevice    58.  5.100 / 58.  5.100
 libavfilter     7. 40.101 /  7. 40.101
 libswscale      5.  3.100 /  5.  3.100
 libswresample   3.  3.100 /  3.  3.100
 libpostproc    55.  3.100 / 55.  3.100
Input #0, rtsp, from
'rtsp://xxx.xxx.xxx.xxx:554/[stream_name]':
 Metadata:
   title           : RTSP Session
 Duration: N/A, start: 0.318111, bitrate: N/A
   Stream #0:0: Video: h264 (High), yuv420p(progressive), 944x1080, 22 fps, 22 tbr, 90k tbn, 180k tbc
Output #0, rtsp, to
'rtsp://yyy.yyy.yyy.yyy/[new_stream_name]':
 Metadata:
   title           : RTSP Session
   encoder         : Lavf58.20.100
   Stream #0:0: Video: h264 (High), yuv420p(progressive), 944x1080, q=2-31, 22 fps, 22 tbr, 90k tbn, 90k tbc
Stream mapping:
 Stream #0:0 -> #0:0 (copy)
Press [q] to stop, [?] for help

  frame=  113 fps= 32 q=-1.0 Lsize=N/A time=00:00:06.77 bitrate=N/A speed=1.92x

  Although when i change output stream container to ’flv’ and protocol to ’rtmp’ it works.

  Any help will be appreciated.