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Rennes Emotion Map 2010-11
19 octobre 2011, par
Mis à jour : Juillet 2013
Langue : français
Type : Texte
Autres articles (67)
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Les images
15 mai 2013 -
Mediabox : ouvrir les images dans l’espace maximal pour l’utilisateur
8 février 2011, parLa visualisation des images est restreinte par la largeur accordée par le design du site (dépendant du thème utilisé). Elles sont donc visibles sous un format réduit. Afin de profiter de l’ensemble de la place disponible sur l’écran de l’utilisateur, il est possible d’ajouter une fonctionnalité d’affichage de l’image dans une boite multimedia apparaissant au dessus du reste du contenu.
Pour ce faire il est nécessaire d’installer le plugin "Mediabox".
Configuration de la boite multimédia
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Publier sur MédiaSpip
13 juin 2013Puis-je poster des contenus à partir d’une tablette Ipad ?
Oui, si votre Médiaspip installé est à la version 0.2 ou supérieure. Contacter au besoin l’administrateur de votre MédiaSpip pour le savoir
Sur d’autres sites (7228)
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FFMPEG/DASH-LL creates audio and video chunks at different rates ; player is confused (404 errors)
26 mai 2021, par DannyI'm trying to create a MPEG-DASH "live" stream from a static file to test various low latency modes. The DASH muxer in FFmpeg creates two AdaptationSets, one for video chunks and one for audio chunks.


However, the audio and video chunk files are not created at the same rate (should they be ?). ie, here
stream0are the video chunks andstream1are the audio chunks. After a few seconds of running, the webroot directory contains :

chunk-stream0-00001.m4s chunk-stream1-00001.m4s 
chunk-stream0-00002.m4s chunk-stream1-00002.m4s 
chunk-stream0-00003.m4s chunk-stream1-00003.m4s 
chunk-stream0-00004.m4s chunk-stream1-00004.m4s 
 chunk-stream1-00005.m4s 
 chunk-stream1-00006.m4s 
 chunk-stream1-00007.m4s 
 chunk-stream1-00008.m4s 
 chunk-stream1-00009.m4s 
master.mpd 
init-stream0.m4s 
init-stream1.m4s 


The stream doesn't load (or play) on either
dash.jsor shaka-player and there are lots of404 (Not Found)errors for the video chunks. The player is requesting chunks from both stream0 and stream1 in sequence, ie, stream0-001 + stream1-001, then stream0-002 + stream1-002 and so on.

But since stream0 only goes from 001 to 004, there are lots of 404 errors as it tries to load stream0-005 through 009.


The gap gets wider after letting FFmpeg run for a while. eg, stream0 is 62 to 75 but stream1 is 174 to 187. Reloading the player page at this point fails with
dash.all.debug.js:15615 [2055][FragmentController] No video bytes to push or stream is inactive.and shows 404 errors stream0 chunk 188 (which doesn't exist yet !)



The FFmpeg command was adopted from DASH streaming from the top-down :


ffmpeg -re -i /mnt/swdevel/TestStreams/H264/ThreeHourMovie.mp4 \
-c:v libx264 -x264-params keyint=120:scenecut=0 -b:v 1M -c:a copy \
-f dash -dash_segment_type mp4 \
 -seg_duration 2 \
 -target_latency 3 \
 -frag_type duration \
 -frag_duration 0.2 \
 -window_size 10 \
 -extra_window_size 3 \
 -streaming 1 \
 -ldash 1 \
 -use_template 1 \
 -use_timeline 0 \
 -write_prft 1 \
 -fflags +nobuffer+flush_packets \
 -format_options "movflags=+cmaf" \
 -utc_timing_url "/pelican/testPlayers/time.php" \
 master.mpd


And the
dash.jsplayer code is very simple :

const srcUrl = "../ottWebRoot/playerTest/master.mpd"; 

var player = dashjs.MediaPlayer().create();

let autoPlay = false;
player.initialize(document.querySelector("#videoTagId"), srcUrl, autoPlay);

player.updateSettings(
{
 streaming :
 {
 lowLatencyEnabled : true,
 liveDelay : 2,
 jumpGaps : true,
 jumpLargeGaps : true,
 smallGapLimit : 1.5,
 }
});


To provide the
UTCTimingelement in the manifest, the smalltime.phpURL returns a UTC time from the web server :

<?php
 print gmdate("Y-m-d\TH:i:s\Z");
?>


(It also shows 404 errors for the latest stream1/audio chunk, that's likely a different problem)


I'm not sure what to try next. Any and suggestions greatly appreciated.


EDIT I


The suggestion by @Anonymous Coward to change the key interval improved things a lot. The chunks for stream0 and stream1 are in lock-step and have identical sequence numbers.


However, there are still many 404 errors, both on initial page load (without pressing play) and during playback.


I ran
watch -n 1 ls -lt code> and compared side-by-side to the errors in the browser console. It's hard to compare but it <em>looks</em> like the browser is trying to fetch files "on the play edge" which haven't yet been created by FFmpeg. See the pic below.

How do I instruct the browser to wait just a bit more before fetching the edge chunks ?




EDIT II


Using
shaka-playerinstead ofdash.jsplays properly without 404 errors. Configured as :

player.configure(
 {
 streaming: 
 {
 lowLatencyMode: true,
 inaccurateManifestTolerance: 0,
 rebufferingGoal: 0.1,
 }
 
 });


Client


- 

- MacOS 10.12
- dash.js latest 3.2.2
- Chrome 79, Safari 12, FireFox v ?








Server


- 

- Apache 2.4.37
- PHP 7.2.4 (for time function only)
- Centos 8








(For reference, here is the mpd file generated by FFmpeg)


<?xml version="1.0" encoding="utf-8"?>
<mpd xmlns="urn:mpeg:dash:schema:mpd:2011" profiles="urn:mpeg:dash:profile:isoff-live:2011" type="dynamic" minimumupdateperiod="PT500S" availabilitystarttime="2021-05-24T14:50:00.263Z" publishtime="2021-05-24T15:22:45.335Z" timeshiftbufferdepth="PT50.0S" maxsegmentduration="PT2.0S" minbuffertime="PT5.0S">
 <programinformation>
 </programinformation>
 <servicedescription>
 <latency target="3000" referenceid="0"></latency>
 </servicedescription>
 <period start="PT0.0S">
 <adaptationset contenttype="video" startwithsap="1" segmentalignment="true" bitstreamswitching="true" framerate="24/1" maxwidth="1280" maxheight="682" par="15:8" lang="und">
 <resync dt="200000" type="0"></resync>
 <representation mimetype="video/mp4" codecs="avc1.64081f" bandwidth="1000000" width="1280" height="682" sar="1023:1024">
 <producerreferencetime inband="true" type="captured" wallclocktime="2021-05-24T14:50:00.263Z" presentationtime="0">
 <utctiming schemeiduri="urn:mpeg:dash:utc:http-xsdate:2014" value="/pelican/testPlayers/time.php"></utctiming>
 </producerreferencetime>
 <resync dt="5000000" type="1"></resync>
 <segmenttemplate timescale="1000000" duration="2000000" availabilitytimeoffset="1.800" availabilitytimecomplete="false" initialization="init-stream$RepresentationID$.m4s" media="chunk-stream$RepresentationID$-$Number%05d$.m4s" startnumber="1">
 </segmenttemplate>
 </representation>
 </adaptationset>
 <adaptationset contenttype="audio" startwithsap="1" segmentalignment="true" bitstreamswitching="true" lang="und">
 <resync dt="200000" type="0"></resync>
 <representation mimetype="audio/mp4" codecs="mp4a.40.2" bandwidth="116317" audiosamplingrate="48000">
 <audiochannelconfiguration schemeiduri="urn:mpeg:dash:23003:3:audio_channel_configuration:2011" value="2"></audiochannelconfiguration>
 <producerreferencetime inband="true" type="captured" wallclocktime="2021-05-24T14:50:00.306Z" presentationtime="0">
 <utctiming schemeiduri="urn:mpeg:dash:utc:http-xsdate:2014" value="/pelican/testPlayers/time.php"></utctiming>
 </producerreferencetime>
 <resync dt="21333" type="1"></resync>
 <segmenttemplate timescale="1000000" duration="2000000" availabilitytimeoffset="1.800" availabilitytimecomplete="false" initialization="init-stream$RepresentationID$.m4s" media="chunk-stream$RepresentationID$-$Number%05d$.m4s" startnumber="1">
 </segmenttemplate>
 </representation>
 </adaptationset>
 </period>
 <utctiming schemeiduri="urn:mpeg:dash:utc:http-xsdate:2014" value="/pelican/testPlayers/time.php"></utctiming>
</mpd>


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sws : move updating the palette higher up
21 mai 2021, par Anton Khirnov -
sws : move initializing dither_error higher up
21 mai 2021, par Anton Khirnov
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