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Médias (1)
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La conservation du net art au musée. Les stratégies à l’œuvre
26 mai 2011
Mis à jour : Juillet 2013
Langue : français
Type : Texte
Autres articles (62)
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Modifier la date de publication
21 juin 2013, parComment 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 -
XMP PHP
13 mai 2011, parDixit Wikipedia, XMP signifie :
Extensible Metadata Platform ou XMP est un format de métadonnées basé sur XML utilisé dans les applications PDF, de photographie et de graphisme. Il a été lancé par Adobe Systems en avril 2001 en étant intégré à la version 5.0 d’Adobe Acrobat.
Étant basé sur XML, il gère un ensemble de tags dynamiques pour l’utilisation dans le cadre du Web sémantique.
XMP permet d’enregistrer sous forme d’un document XML des informations relatives à un fichier : titre, auteur, historique (...) -
Use, discuss, criticize
13 avril 2011, parTalk to people directly involved in MediaSPIP’s development, or to people around you who could use MediaSPIP to share, enhance or develop their creative projects.
The bigger the community, the more MediaSPIP’s potential will be explored and the faster the software will evolve.
A discussion list is available for all exchanges between users.
Sur d’autres sites (5996)
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Java Playing Sound From YouTube
8 mai 2022, par etkmlmI'm in a LWJGL game and want to play sound from YouTube. I have the stream link but can't play it anymore.


public void playMusic(Music m) throws IOException {
 String uri = m.getUrl();
 URL url = new URL(uri);
 try{
 Process p = new ProcessBuilder().command("ffmpeg.exe", "-i", uri, "-acodec", "pcm_u8", "-ar", "22050", "-f", "wav", "pipe:1").redirectError(ProcessBuilder.Redirect.INHERIT).start();

 AudioInputStream str = AudioSystem.getAudioInputStream(p.getInputStream());
 Clip clip = AudioSystem.getClip();
 clip.open(str);
 clip.start();

 }
 catch (Exception e){
 e.printStackTrace();
 }

}



It throws "Chunk size too big" error. I started ffmpeg alone but in this time, ffmpeg throws "invalid argumentsize=" error.


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FFmpeg cant recognize 3 channels with each 32 bit
4 avril 2022, par ChryfiI am writing the linearized depth buffer of a game to openEXR using FFmpeg. Unfortunately, FFmpeg does not adhere to the openEXR file specification fully (like allowing unsigned integer for one channel) so I am writing one float channel to openEXR, which is put into the green channel with this command
-f rawvideo -pix_fmt grayf32be -s %WIDTH%x%HEIGHT% -r %FPS% -i - -vf %DEFVF% -preset ultrafast -tune zerolatency -qp 6 -compression zip1 -pix_fmt gbrpf32le %NAME%_depth_%d.exr
.

The float range is from 0F to 1F and it is linear. I can confirm that the calculation and linearization is correct by testing 16 bit integer (per pixel component) PNG in Blender compositor. The 16 bit integer data is written like this
short s = (short) (linearzieDepth(depth) * (Math.pow(2,16) - 1))
whereas for float the linearized value is directly written to OpenEXR without multiplying with a value.

However, when viewing the openEXR file it doesn't have the same "gradient" as the 16 bit png... when viewing them side by side, it appears as if the values near 0 are not linear, and they are not as dark as they should be like in the 16 bit png.
(And yes, I set the image node to linear), and comparing it with 3d tracking data from the game I cant reproduce the depth and cant mask things using the depth buffer where as with the png I can.


How is it possible for a linear float range to turn out so different to a linear integer range in an image ?


UPDATE :


I now write 3 channels to the ffmpeg with this code


float f2 = this.linearizeDepth(depth);

buffer.putFloat(f2);
buffer.putFloat(0);
buffer.putFloat(0);



the byte buffer is of the size
width * height * 3 * 4
-> 3 channels with each 4 bytes. The command is now-f rawvideo -pix_fmt gbrpf32be -s %WIDTH%x%HEIGHT% -r %FPS% -i - -vf %DEFVF% -preset ultrafast -tune zerolatency -qp 6 -compression zip1 -pix_fmt gbrpf32le %NAME%_depth_%d.exr
which should mean that the input (byte buffer) is expecting 32 bit floats with 3 channels.

FFmpeg is somehow splitting up channels or whatever... could be a bug, could be my fault ?


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Writing linear float range to openEXR turns out non linear
3 avril 2022, par ChryfiI am writing the linearized depth buffer of a game to openEXR using FFmpeg. Unfortunately, FFmpeg does not adhere to the openEXR file specification fully (like allowing unsigned integer for one channel) so I am writing one float channel to openEXR, which is put into the green channel with this command
-f rawvideo -pix_fmt grayf32be -s %WIDTH%x%HEIGHT% -r %FPS% -i - -vf %DEFVF% -preset ultrafast -tune zerolatency -qp 6 -compression zip1 -pix_fmt gbrpf32le %NAME%_depth_%d.exr
.

The float range is from 0F to 1F and it is linear. I can confirm that the calculation and linearization is correct by testing 16 bit integer (per pixel component) PNG in Blender compositor. The 16 bit integer data is written like this
short s = (short) (linearzieDepth(depth) * (Math.pow(2,16) - 1))
whereas for float the linearized value is directly written to OpenEXR without multiplying with a value.

However, when viewing the openEXR file it doesn't have the same "gradient" as the 16 bit png... when viewing them side by side, it appears as if the values near 0 are not linear, and they are not as dark as they should be like in the 16 bit png.
(And yes, I set the image node to linear), and comparing it with 3d tracking data from the game I cant reproduce the depth and cant mask things using the depth buffer where as with the png I can.


How is it possible for a linear float range to turn out so different to a linear integer range in an image ?