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  • Ajouter des informations spécifiques aux utilisateurs et autres modifications de comportement liées aux auteurs

    12 avril 2011, par

    La manière la plus simple d’ajouter des informations aux auteurs est d’installer le plugin Inscription3. Il permet également de modifier certains comportements liés aux utilisateurs (référez-vous à sa documentation pour plus d’informations).
    Il est également possible d’ajouter des champs aux auteurs en installant les plugins champs extras 2 et Interface pour champs extras.

  • Modifier la date de publication

    21 juin 2013, par

    Comment changer la date de publication d’un média ?
    Il faut au préalable rajouter un champ "Date de publication" dans le masque de formulaire adéquat :
    Administrer > Configuration des masques de formulaires > Sélectionner "Un média"
    Dans la rubrique "Champs à ajouter, cocher "Date de publication "
    Cliquer en bas de la page sur Enregistrer

  • Contribute to documentation

    13 avril 2011

    Documentation is vital to the development of improved technical capabilities.
    MediaSPIP welcomes documentation by users as well as developers - including : critique of existing features and functions articles contributed by developers, administrators, content producers and editors screenshots to illustrate the above translations of existing documentation into other languages
    To contribute, register to the project users’ mailing (...)

Sur d’autres sites (4997)

  • Three.js video texture displays green on Chrome mobile, wrong encoding ?

    19 mai 2015, par beeb

    I am trying to make a video texture "skybox" that works on mobile browsers with Three.js. So far, I’ve been able to implement this and it works great on desktop browsers. The problem is, when viewing the animation in Chrome mobile (42.0.2311.111 on Android 5.0.2), the video appears all green with a few artifacts. I tried with mp4 (encoded with ffmpeg libx264) and ogv (ffmpeg libtheora) videos and they both fail to work (mp4 is green as stated, and ogv doesn’t display at all - black). Is the encoding the problem or webgl ? The strange thing is that my method is the same as this method : http://jeromeetienne.github.io/threex.videotexture/examples/videotexture.html
    But my Chrome mobile browser can play this example fine, so I’m guessing the encoding must be the problem ?

    Here are the command lines I used to generate the videos :

    ffmpeg -framerate 30 -i %05d.png -c:v libtheora -qscale:v 8 -r 30 outputfile.ogv
    
ffmpeg -framerate 30 -i %05d.png -c:v libx264 -qscale:v 8 -r 30 outputfile.mp4

    Here’s the full code, even though I don’t think the problem originates from this : https://jsfiddle.net/rufn75ef/ (you have to hit the play button, autoplay doesn’t work on mobile so I disabled it for this example)

    video = document.createElement('video');
    
video.crossOrigin = "Anonymous";
    
var canPlayMp4 = document.createElement('video').canPlayType('video/mp4') !== '' ? true : false;
    
var canPlayOgg = document.createElement('video').canPlayType('video/ogg') !== '' ? true : false;
    
if (canPlayMp4) {
    
    video.src = 'vid.mp4';
    
} else if (canPlayOgg) {
    
    video.src = 'vid.ogv';
    
} else {
    
    alert('Your browser can\'t play video, please view this site in a modern desktop browser.');
    
}
    
video.muted = true;
    
video.loop = true;
    

    
video.width = 358;
    
video.height = 264;
    

    
video.load(); //do after source change
    

    
videoTexture = new THREE.Texture(video);
    
videoTexture.minFilter = THREE.NearestFilter;
    
videoTexture.magFilter = THREE.NearestFilter;

    If you are able to test, do you experience the same problem ? How should I encode my videos using ffmpeg to maximize mobile compatibility ?

    Thanks in advance

  • VLC command line : RTSP to mp4 file (video + audio)

    8 février 2016, par Dmitriy Gerashenko

    Win 7 x64.

    When I watch this link in VLC player all is fine :

    rtsp ://184.72.239.149/vod/mp4:BigBuckBunny_175k.mov

    When I try to capture link to file and to display :

    • There is video without sound on display.
    • Created file is not playable.

    Command :

    vlc.exe -vvv "rtsp://184.72.239.149/vod/mp4:BigBuckBunny_175k.mov" --sout="#transcode{venc=ffmpeg,vcodec=mp4v,vfilter=canvas{width=800,height=600},aenc=ffmpeg{strict=-2},acodec=mp4a}:duplicate{dst=display,dst=standard{access=file,mux=mp4,dst=video.mp4}"

    There are some errors in log, for example : MPEG4GenericRTPSource Warning: Unknown or unsupported "mode": AAC-hbr. Is it cause of my problems ? How to solve my issue ?

    Complete log (from VLCJ) :

    cd C:\Users\gda\Documents\NetBeansProjects\Video; "JAVA_HOME=C:\\Program Files (x86)\\Java\\jdk1.8.0_71" cmd /c "\"\"C:\\Users\\gda\\AppData\\Roaming\\NetBeans\\8.0.2\\maven\\bin\\mvn.bat\" -Dexec.args=\"-classpath %classpath ru.cherezweb.app.video.Video\" -Dexec.executable=\"C:\\Program Files (x86)\\Java\\jdk1.8.0_71\\bin\\java.exe\" -Dmaven.ext.class.path=C:\\Users\\gda\\AppData\\Roaming\\NetBeans\\8.0.2\\maven-nblib\\netbeans-eventspy.jar -Dfile.encoding=UTF-8 process-classes org.codehaus.mojo:exec-maven-plugin:1.2.1:exec\""
    
Scanning for projects...
    

    
------------------------------------------------------------------------
    
Building Video 1.0-SNAPSHOT
    
------------------------------------------------------------------------
    

    
--- maven-resources-plugin:2.5:resources (default-resources) @ Video ---
    
[debug] execute contextualize
    
Using 'UTF-8' encoding to copy filtered resources.
    
skip non existing resourceDirectory C:\Users\gda\Documents\NetBeansProjects\Video\src\main\resources
    

    
--- maven-compiler-plugin:2.3.2:compile (default-compile) @ Video ---
    
Nothing to compile - all classes are up to date
    

    
--- exec-maven-plugin:1.2.1:exec (default-cli) @ Video ---
    
20:37:29.097 [main] INFO  uk.co.caprica.vlcj.Info - vlcj: 3.10.1
    
20:37:29.101 [main] INFO  uk.co.caprica.vlcj.Info - java: 1.8.0_71 Oracle Corporation
    
20:37:29.101 [main] INFO  uk.co.caprica.vlcj.Info - java home: C:\Program Files (x86)\Java\jdk1.8.0_71\jre
    
20:37:29.101 [main] INFO  uk.co.caprica.vlcj.Info - os: Windows 10 10.0 x86
    
20:37:29.103 [main] DEBUG u.c.c.vlcj.discovery.NativeDiscovery - discover()
    
20:37:29.103 [main] DEBUG u.c.c.vlcj.discovery.NativeDiscovery - jnaLibraryPath=null
    
20:37:29.103 [main] DEBUG u.c.c.vlcj.discovery.NativeDiscovery - discoveryStrategy=uk.co.caprica.vlcj.discovery.linux.DefaultLinuxNativeDiscoveryStrategy@176c05c
    
20:37:29.104 [main] DEBUG u.c.c.vlcj.discovery.NativeDiscovery - supported=false
    
20:37:29.104 [main] DEBUG u.c.c.vlcj.discovery.NativeDiscovery - discoveryStrategy=uk.co.caprica.vlcj.discovery.windows.DefaultWindowsNativeDiscoveryStrategy@1eb6432
    
20:37:29.104 [main] DEBUG u.c.c.vlcj.discovery.NativeDiscovery - supported=true
    
20:37:29.104 [main] DEBUG u.c.c.v.d.AbstractNativeDiscoveryStrategy - discover()
    
20:37:29.105 [main] DEBUG u.c.c.v.r.windows.WindowsRuntimeUtil - getVlcInstallDir()
    
20:37:29.430 [main] DEBUG u.c.c.v.d.AbstractNativeDiscoveryStrategy - directoryNames=[C:\Program Files (x86)\VideoLAN\VLC, C:\Users\gda\Documents\NetBeansProjects\Video, C:\Program Files\Broadcom\Broadcom 802.11 Network Adapter, C:\Program Files (x86)\Intel\iCLS Client\, C:\Program Files\Intel\iCLS Client\, C:\PROGRAMDATA\ORACLE\JAVA\JAVAPATH, C:\Windows\SYSTEM32, C:\Windows, C:\Windows\SYSTEM32\WBEM, C:\Windows\SYSTEM32\WINDOWSPOWERSHELL\V1.0\, C:\PROGRAM FILES\INTEL\INTEL(R) MANAGEMENT ENGINE COMPONENTS\DAL, C:\PROGRAM FILES\INTEL\INTEL(R) MANAGEMENT ENGINE COMPONENTS\IPT, C:\PROGRAM FILES (X86)\INTEL\INTEL(R) MANAGEMENT ENGINE COMPONENTS\DAL, C:\PROGRAM FILES (X86)\INTEL\INTEL(R) MANAGEMENT ENGINE COMPONENTS\IPT, C:\Program Files\Intel\Intel(R) Management Engine Components\DAL, C:\Program Files\Intel\Intel(R) Management Engine Components\IPT, C:\Program Files (x86)\Intel\Intel(R) Management Engine Components\DAL, C:\Program Files (x86)\Intel\Intel(R) Management Engine Components\IPT, C:\Program Files\WIDCOMM\Bluetooth Software\, C:\Program Files\WIDCOMM\Bluetooth Software\syswow64, C:\Program Files\TortoiseSVN\bin, C:\Program Files (x86)\NVIDIA Corporation\PhysX\Common, C:\Program Files\OpenVPN\bin, C:\WINDOWS\system32, C:\WINDOWS, C:\WINDOWS\System32\Wbem, C:\WINDOWS\System32\WindowsPowerShell\v1.0\, C:\Program Files\TortoiseGit\bin, C:\Program Files (x86)\Skype\Phone\]
    
20:37:29.430 [main] DEBUG u.c.c.v.d.AbstractNativeDiscoveryStrategy - directoryName=C:\Program Files (x86)\VideoLAN\VLC
    
20:37:29.430 [main] DEBUG u.c.c.v.d.AbstractNativeDiscoveryStrategy - Matched 'libvlc.dll' in 'C:\Program Files (x86)\VideoLAN\VLC'
    
20:37:29.430 [main] DEBUG u.c.c.v.d.AbstractNativeDiscoveryStrategy - Matched 'libvlccore.dll' in 'C:\Program Files (x86)\VideoLAN\VLC'
    
20:37:29.430 [main] DEBUG u.c.c.v.d.AbstractNativeDiscoveryStrategy - Matched all required files
    
20:37:29.430 [main] DEBUG u.c.c.v.d.AbstractNativeDiscoveryStrategy - result=C:\Program Files (x86)\VideoLAN\VLC
    
20:37:29.430 [main] DEBUG u.c.c.vlcj.discovery.NativeDiscovery - path=C:\Program Files (x86)\VideoLAN\VLC
    
20:37:29.431 [main] INFO  u.c.c.vlcj.discovery.NativeDiscovery - Discovery found libvlc at 'C:\Program Files (x86)\VideoLAN\VLC'
    
true
    
2.2.1 Terry Pratchett (Weatherwax)
    
20:37:29.490 [main] DEBUG u.c.c.vlcj.player.MediaPlayerFactory - initX=null
    
20:37:29.494 [main] INFO  u.c.c.vlcj.binding.LibVlcFactory - vlc: 2.2.1 Terry Pratchett (Weatherwax), changeset 2.2.1-0-ga425c42
    
20:37:29.494 [main] INFO  u.c.c.vlcj.binding.LibVlcFactory - libvlc: C:\Program Files (x86)\VideoLAN\VLC\libvlc.dll
    
20:37:29.494 [main] DEBUG u.c.c.vlcj.player.MediaPlayerFactory - MediaPlayerFactory(libvlc=Proxy interface to Native Library ,libvlcArgs=[])
    
20:37:29.494 [main] DEBUG u.c.c.vlcj.player.MediaPlayerFactory - jna.library.path=null
    
20:37:29.494 [main] DEBUG u.c.c.vlcj.player.MediaPlayerFactory - VLC_PLUGIN_PATH=null
    
20:37:29.529 [main] DEBUG u.c.c.vlcj.player.MediaPlayerFactory - instance=native@0x1195650 (uk.co.caprica.vlcj.binding.internal.libvlc_instance_t@1195650)
    
20:37:29.529 [main] DEBUG u.c.c.vlcj.player.MediaPlayerFactory - equalizerAvailable=true
    
20:37:29.529 [main] DEBUG u.c.c.vlcj.player.MediaPlayerFactory - createEqualizerBandFrequencies()
    
20:37:29.529 [main] DEBUG u.c.c.vlcj.player.MediaPlayerFactory - numBands=10
    
20:37:29.530 [main] DEBUG u.c.c.vlcj.player.MediaPlayerFactory - result=[31.25, 62.5, 125.0, 250.0, 500.0, 1000.0, 2000.0, 4000.0, 8000.0, 16000.0]
    
20:37:29.530 [main] DEBUG u.c.c.vlcj.player.MediaPlayerFactory - createEqualizerPresetNames()
    
20:37:29.530 [main] DEBUG u.c.c.vlcj.player.MediaPlayerFactory - numPresets=18
    
20:37:29.530 [main] DEBUG u.c.c.vlcj.player.MediaPlayerFactory - result=[Flat, Classical, Club, Dance, Full bass, Full bass and treble, Full treble, Headphones, Large Hall, Live, Party, Pop, Reggae, Rock, Ska, Soft, Soft rock, Techno]
    
20:37:29.530 [main] DEBUG u.c.c.vlcj.player.MediaPlayerFactory - newHeadlessMediaPlayer()
    
20:37:29.538 [main] DEBUG u.c.c.vlcj.player.DefaultMediaPlayer - DefaultMediaPlayer(libvlc=Proxy interface to Native Library , instance=native@0x1195650 (uk.co.caprica.vlcj.binding.internal.libvlc_instance_t@1195650))
    
20:37:29.538 [main] DEBUG u.c.c.vlcj.player.DefaultMediaPlayer - createInstance()
    
20:37:29.543 [main] DEBUG u.c.c.vlcj.player.DefaultMediaPlayer - mediaPlayerInstance=native@0x16853ac4 (uk.co.caprica.vlcj.binding.internal.libvlc_media_player_t@16853ac4)
    
20:37:29.544 [main] DEBUG u.c.c.vlcj.player.DefaultMediaPlayer - mediaPlayerEventManager=native@0x16878818 (uk.co.caprica.vlcj.binding.internal.libvlc_event_manager_t@16878818)
    
20:37:29.544 [main] DEBUG u.c.c.vlcj.player.DefaultMediaPlayer - registerEventListener()
    
20:37:29.546 [main] DEBUG u.c.c.vlcj.player.DefaultMediaPlayer - event=libvlc_MediaPlayerMediaChanged
    
20:37:29.567 [main] DEBUG u.c.c.vlcj.player.DefaultMediaPlayer - result=0
    
20:37:29.567 [main] DEBUG u.c.c.vlcj.player.DefaultMediaPlayer - event=libvlc_MediaPlayerNothingSpecial
    
20:37:29.567 [main] DEBUG u.c.c.vlcj.player.DefaultMediaPlayer - result=0
    
20:37:29.567 [main] DEBUG u.c.c.vlcj.player.DefaultMediaPlayer - event=libvlc_MediaPlayerOpening
    
20:37:29.567 [main] DEBUG u.c.c.vlcj.player.DefaultMediaPlayer - result=0
    
20:37:29.567 [main] DEBUG u.c.c.vlcj.player.DefaultMediaPlayer - event=libvlc_MediaPlayerBuffering
    
20:37:29.567 [main] DEBUG u.c.c.vlcj.player.DefaultMediaPlayer - result=0
    
20:37:29.567 [main] DEBUG u.c.c.vlcj.player.DefaultMediaPlayer - event=libvlc_MediaPlayerPlaying
    
20:37:29.567 [main] DEBUG u.c.c.vlcj.player.DefaultMediaPlayer - result=0
    
20:37:29.567 [main] DEBUG u.c.c.vlcj.player.DefaultMediaPlayer - event=libvlc_MediaPlayerPaused
    
20:37:29.568 [main] DEBUG u.c.c.vlcj.player.DefaultMediaPlayer - result=0
    
20:37:29.568 [main] DEBUG u.c.c.vlcj.player.DefaultMediaPlayer - event=libvlc_MediaPlayerStopped
    
20:37:29.568 [main] DEBUG u.c.c.vlcj.player.DefaultMediaPlayer - result=0
    
20:37:29.568 [main] DEBUG u.c.c.vlcj.player.DefaultMediaPlayer - event=libvlc_MediaPlayerForward
    
20:37:29.568 [main] DEBUG u.c.c.vlcj.player.DefaultMediaPlayer - result=0
    
20:37:29.568 [main] DEBUG u.c.c.vlcj.player.DefaultMediaPlayer - event=libvlc_MediaPlayerBackward
    
20:37:29.568 [main] DEBUG u.c.c.vlcj.player.DefaultMediaPlayer - result=0
    
20:37:29.568 [main] DEBUG u.c.c.vlcj.player.DefaultMediaPlayer - event=libvlc_MediaPlayerEndReached
    
20:37:29.568 [main] DEBUG u.c.c.vlcj.player.DefaultMediaPlayer - result=0
    
20:37:29.569 [main] DEBUG u.c.c.vlcj.player.DefaultMediaPlayer - event=libvlc_MediaPlayerEncounteredError
    
20:37:29.569 [main] DEBUG u.c.c.vlcj.player.DefaultMediaPlayer - result=0
    
20:37:29.569 [main] DEBUG u.c.c.vlcj.player.DefaultMediaPlayer - event=libvlc_MediaPlayerTimeChanged
    
20:37:29.569 [main] DEBUG u.c.c.vlcj.player.DefaultMediaPlayer - result=0
    
20:37:29.569 [main] DEBUG u.c.c.vlcj.player.DefaultMediaPlayer - event=libvlc_MediaPlayerPositionChanged
    
20:37:29.569 [main] DEBUG u.c.c.vlcj.player.DefaultMediaPlayer - result=0
    
20:37:29.569 [main] DEBUG u.c.c.vlcj.player.DefaultMediaPlayer - event=libvlc_MediaPlayerSeekableChanged
    
20:37:29.569 [main] DEBUG u.c.c.vlcj.player.DefaultMediaPlayer - result=0
    
20:37:29.569 [main] DEBUG u.c.c.vlcj.player.DefaultMediaPlayer - event=libvlc_MediaPlayerPausableChanged
    
20:37:29.569 [main] DEBUG u.c.c.vlcj.player.DefaultMediaPlayer - result=0
    
20:37:29.569 [main] DEBUG u.c.c.vlcj.player.DefaultMediaPlayer - event=libvlc_MediaPlayerTitleChanged
    
20:37:29.569 [main] DEBUG u.c.c.vlcj.player.DefaultMediaPlayer - result=0
    
20:37:29.569 [main] DEBUG u.c.c.vlcj.player.DefaultMediaPlayer - event=libvlc_MediaPlayerSnapshotTaken
    
20:37:29.570 [main] DEBUG u.c.c.vlcj.player.DefaultMediaPlayer - result=0
    
20:37:29.570 [main] DEBUG u.c.c.vlcj.player.DefaultMediaPlayer - event=libvlc_MediaPlayerLengthChanged
    
20:37:29.570 [main] DEBUG u.c.c.vlcj.player.DefaultMediaPlayer - result=0
    
20:37:29.570 [main] DEBUG u.c.c.vlcj.player.DefaultMediaPlayer - event=libvlc_MediaPlayerVout
    
20:37:29.570 [main] DEBUG u.c.c.vlcj.player.DefaultMediaPlayer - result=0
    
20:37:29.570 [main] DEBUG u.c.c.vlcj.player.DefaultMediaPlayer - event=libvlc_MediaPlayerScrambledChanged
    
20:37:29.570 [main] DEBUG u.c.c.vlcj.player.DefaultMediaPlayer - result=0
    
20:37:29.572 [main] DEBUG u.c.c.vlcj.player.DefaultMediaPlayer - playMedia(mrl=rtsp://184.72.239.149/vod/mp4:BigBuckBunny_175k.mov,mediaOptions=[:sout=#transcode{venc=ffmpeg,vcodec=mp4v,vfilter=canvas{width=800,height=600},aenc=ffmpeg{strict=-2},acodec=mp4a}:duplicate{dst=display,dst=standard{access=file,mux=mp4,dst=yahoo.m4v}}])
    
20:37:29.573 [main] DEBUG u.c.c.v.player.MediaResourceLocator - encodeMrl(mrl=rtsp://184.72.239.149/vod/mp4:BigBuckBunny_175k.mov)
    
20:37:29.573 [main] DEBUG u.c.c.v.player.MediaResourceLocator - MRL does not contain any Unicode characters
    
20:37:29.573 [main] DEBUG u.c.c.v.player.MediaResourceLocator - result=rtsp://184.72.239.149/vod/mp4:BigBuckBunny_175k.mov
    
20:37:29.574 [main] DEBUG u.c.c.vlcj.player.DefaultMediaPlayer - playMedia(media=SimpleMedia[mrl=rtsp://184.72.239.149/vod/mp4:BigBuckBunny_175k.mov,mediaOptions=[Ljava.lang.String;@17c74e5])
    
20:37:29.574 [main] DEBUG u.c.c.vlcj.player.DefaultMediaPlayer - prepareMedia(media=SimpleMedia[mrl=rtsp://184.72.239.149/vod/mp4:BigBuckBunny_175k.mov,mediaOptions=[Ljava.lang.String;@17c74e5])
    
20:37:29.574 [main] DEBUG u.c.c.vlcj.player.DefaultMediaPlayer - setMedia(media=SimpleMedia[mrl=rtsp://184.72.239.149/vod/mp4:BigBuckBunny_175k.mov,mediaOptions=[Ljava.lang.String;@17c74e5])
    
20:37:29.574 [main] DEBUG u.c.c.vlcj.player.DefaultMediaPlayer - createMediaInstance(media=SimpleMedia[mrl=rtsp://184.72.239.149/vod/mp4:BigBuckBunny_175k.mov,mediaOptions=[Ljava.lang.String;@17c74e5])
    
20:37:29.574 [main] DEBUG u.c.c.vlcj.player.DefaultMediaPlayer - Treating mrl as a location
    
20:37:29.574 [main] DEBUG u.c.c.vlcj.player.DefaultMediaPlayer - mediaInstance=native@0x16876500 (uk.co.caprica.vlcj.binding.internal.libvlc_media_t@16876500)
    
20:37:29.574 [main] DEBUG u.c.c.vlcj.player.DefaultMediaPlayer - mediaOption=:sout=#transcode{venc=ffmpeg,vcodec=mp4v,vfilter=canvas{width=800,height=600},aenc=ffmpeg{strict=-2},acodec=mp4a}:duplicate{dst=display,dst=standard{access=file,mux=mp4,dst=yahoo.m4v}}
    
20:37:29.575 [main] DEBUG u.c.c.vlcj.player.DefaultMediaPlayer - registerMediaEventListener()
    
20:37:29.575 [main] DEBUG u.c.c.vlcj.player.DefaultMediaPlayer - event=libvlc_MediaMetaChanged
    
20:37:29.575 [main] DEBUG u.c.c.vlcj.player.DefaultMediaPlayer - result=0
    
20:37:29.575 [main] DEBUG u.c.c.vlcj.player.DefaultMediaPlayer - event=libvlc_MediaSubItemAdded
    
20:37:29.575 [main] DEBUG u.c.c.vlcj.player.DefaultMediaPlayer - result=0
    
20:37:29.576 [main] DEBUG u.c.c.vlcj.player.DefaultMediaPlayer - event=libvlc_MediaDurationChanged
    
20:37:29.576 [main] DEBUG u.c.c.vlcj.player.DefaultMediaPlayer - result=0
    
20:37:29.576 [main] DEBUG u.c.c.vlcj.player.DefaultMediaPlayer - event=libvlc_MediaParsedChanged
    
20:37:29.576 [main] DEBUG u.c.c.vlcj.player.DefaultMediaPlayer - result=0
    
20:37:29.576 [main] DEBUG u.c.c.vlcj.player.DefaultMediaPlayer - event=libvlc_MediaFreed
    
20:37:29.576 [main] DEBUG u.c.c.vlcj.player.DefaultMediaPlayer - result=0
    
20:37:29.576 [main] DEBUG u.c.c.vlcj.player.DefaultMediaPlayer - event=libvlc_MediaStateChanged
    
20:37:29.576 [main] DEBUG u.c.c.vlcj.player.DefaultMediaPlayer - result=0
    
20:37:29.576 [main] DEBUG u.c.c.vlcj.player.DefaultMediaPlayer - event=libvlc_MediaSubItemTreeAdded
    
20:37:29.576 [main] DEBUG u.c.c.vlcj.player.DefaultMediaPlayer - result=0
    
20:37:29.585 [main] DEBUG u.c.c.vlcj.player.DefaultMediaPlayer - mrl(mediaInstance=native@0x16876500 (uk.co.caprica.vlcj.binding.internal.libvlc_media_t@16876500))
    
20:37:29.587 [pool-2-thread-1] DEBUG u.c.c.vlcj.player.DefaultMediaPlayer - mediaChanged(mediaPlayer=uk.co.caprica.vlcj.player.headless.DefaultHeadlessMediaPlayer@1727f27,media=native@0x16876500 (uk.co.caprica.vlcj.binding.internal.libvlc_media_t@16876500),mrl=rtsp://184.72.239.149/vod/mp4:BigBuckBunny_175k.mov)
    
20:37:29.588 [pool-2-thread-1] DEBUG u.c.c.vlcj.player.DefaultMediaPlayer - Raising event for new media
    
20:37:29.588 [main] DEBUG u.c.c.vlcj.player.DefaultMediaPlayer - result=true
    
20:37:29.588 [main] DEBUG u.c.c.vlcj.player.DefaultMediaPlayer - play()
    
20:37:29.593 [main] DEBUG u.c.c.vlcj.player.DefaultMediaPlayer - after play
    
MPEG4GenericRTPSource Warning: Unknown or unsupported "mode": AAC-hbr
    
[1682c9cc] core input error: ES_OUT_RESET_PCR called
    
[16f79744] core decoder error: cannot continue streaming due to errors
    
[1682c9cc] core input error: ES_OUT_RESET_PCR called
    
[h264 @ 1702ba80] decode_slice_header error
    
[h264 @ 1702ba80] decode_slice_header error
    
[16828134] stream_out_transcode stream out: input interval 41666 (base 2)
    
[16828134] stream_out_transcode stream out: output interval 41666 (base 1)

  • Why JPEG compressing an uncompressed image differs its original (FFmpeg, NvJPEG, ...)

    22 juin 2021, par Fruchtzwerg

    I am currently struggling to understand why recompressing an uncompressed JPEG image differs its original.

    


    It's clear, that JPEG is a lossy compression, but what if the image to compress is already uncompressed, which means all sampling losses are already included ? In other words : Downsampling and DCT should be inversable at this point without loosing data.

    


    JPEG algorithm

    


    To make sure losses are not effected by the color space conversion, this step is skipped and YUV images are used.

    


      

    1. Compress YUV image to JPEG (image.yuv —> image.yuv.jpg)

      2. 


    2. Uncompress JPEG image to YUV image (image.yuv.jpg —> image.yuv.jpg.yuv)

      3. 


    3. Compress YUV image to JPEG (image.yuv.jpg.yuv —> image.yuv.jpg.yuv.jpg)

      4. 


    4. Uncompress JPEG image to YUV image (image.yuv.jpg.yuv.jpg —> image.yuv.jpg.yuv.jpg.yuv)

      5. 


    


    Step 1 includes a lossy compression, so we will not deal with this step anymore. For me, intresting is what happens afterwards :

    


    Uncompressing the JPEG image back to YUV (step 2) leads to an image which perfectly fits all sampling steps if compressed again (step 3). So the JPEG image after step 3 should (from my understanding) be exactly the same as after step 1. Also the YUV images after step 4 and step 2 should equal each other.

    


    Looking at the steps for one 8x8 block the following simplified sequence should illustrate what I am trying to descibe. Lets start with the original YUV image, which can only be decompressed loosing all decimal places :

    


    [ 1.123, 2.345, 3.456, ... ]    (YUV)
    DTC + Quantization
[ -26, -3, -6, ... ]            (Quantized frequency space)
    Inverse DTC + Quantization
[ 1, 2, 3, ... ]                (YUV)


    


    Doing this with input, which already matches all steps, which may lead to loss of data afterwards (using round numbers in my example), the decompressed image should match its original :

    


    [ 1, 2, 3, ... ]                (YUV)
    DTC + Quantization
[ -26, -3, -6, ... ]            (Quantized frequency space)
    Inverse DTC + Quantization
[ 1, 2, 3, ... ]                (YUV)


    


    There are also some sources and discussions, which are confirming my idea :

    


    


    So much for theory. In praxis, I've runned these steps using ffmpeg and Nvidias jpeg samples (using NvJPEGEncoder).

    


    ffmpeg :

    


    #Create YUV image
ffmpeg -y -i image.jpg -s 1920x1080 -pix_fmt yuv420p image.yuv
#YUV to JPEG
ffmpeg -y -s 1920x1080 -pix_fmt yuv420p -i image.yuv image.yuv.jpg
#JPEG TO YUV
ffmpeg -y -i image.yuv.jpg -s 1920x1080 -pix_fmt yuv420p image.yuv.jpg.yuv
#YUV to JPEG
ffmpeg -y -s 1920x1080 -pix_fmt yuv420p -i image.yuv.jpg.yuv image.yuv.jpg.yuv.jpg
#JPEG TO YUV
ffmpeg -y -i image.yuv.jpg.yuv.jpg -s 1920x1080 -pix_fmt yuv420p image.yuv.jpg.yuv.jpg.yuv
#YUV to JPEG
ffmpeg -y -s 1920x1080 -pix_fmt yuv420p -i image.yuv.jpg.yuv.jpg.yuv image.yuv.jpg.yuv.jpg.yuv.jpg


    


    Nvidia :

    


    #Create YUV image
./jpeg_decode num_files 1 image.jpg image.yuv
#YUV to JPEG
./jpeg_encode image.yuv 1920 1080 image.yuv.jpg
#JPEG TO YUV
./jpeg_decode num_files 1 image.yuv.jpg image.yuv.jpg.yuv
#YUV to JPEG
./jpeg_encode image.yuv.jpg.yuv 1920 1080 image.yuv.jpg.yuv.jpg
#JPEG TO YUV
./jpeg_decode num_files 1 image.yuv.jpg.yuv.jpg image.yuv.jpg.yuv.jpg.yuv
#YUV to JPEG
./jpeg_encode image.yuv.jpg.yuv.jpg.yuv 1920 1080 image.yuv.jpg.yuv.jpg.yuv.jpg


    


    But a comparison of the images

    


      

    • image.yuv.jpg.yuv and image.yuv.jpg.yuv.jpg.yuv

      • 


    • image.yuv.jpg.yuv.jpg and image.yuv.jpg.yuv.jpg.yuv.jpg

      • 


    


    showing differences in the files. That brings me to my question why and where the difference gets happen, since from my understanding the files should be equal.

    


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