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Géodiversité
9 septembre 2011, par ,
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USGS Real-time Earthquakes
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La conservation du net art au musée. Les stratégies à l’œuvre
26 mai 2011
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Podcasting Legal guide
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Creativecommons informational flyer
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Autres articles (59)
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Gestion générale des documents
13 mai 2011, parMédiaSPIP ne modifie jamais le document original mis en ligne.
Pour chaque document mis en ligne il effectue deux opérations successives : la création d’une version supplémentaire qui peut être facilement consultée en ligne tout en laissant l’original téléchargeable dans le cas où le document original ne peut être lu dans un navigateur Internet ; la récupération des métadonnées du document original pour illustrer textuellement le fichier ;
Les tableaux ci-dessous expliquent ce que peut faire MédiaSPIP (...) -
Problèmes fréquents
10 mars 2010, parPHP et safe_mode activé
Une des principales sources de problèmes relève de la configuration de PHP et notamment de l’activation du safe_mode
La solution consiterait à soit désactiver le safe_mode soit placer le script dans un répertoire accessible par apache pour le site -
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
Dès (...)
Sur d’autres sites (5416)
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Path and bundle strings have different number of entries ; invalid manifest : xuggle-xuggler
7 décembre 2013, par henrycharlesI am new to multimedia.I want to make a project for live video chat in java. Googling around I found about Xuggler.I successfully downloaded all the jars given in this How do you install the latest version of Xuggler (5.4, as of 18/05/2013) in eclipse ? .
and tried executing sample code from http://www.javacodegeeks.com/2011/02/xuggler-tutorial-frames-capture-video.html I am not getting any compilation error but the following runtime error. Any help would be much appreciated.
com.xuggle.ferry.JNIManifest - path and bundle strings have different number of entries ; invalid manifest : xuggle-xuggler
import java.awt.image.BufferedImage;
import java.io.File;
import java.io.IOException;
import javax.imageio.ImageIO;
import com.xuggle.mediatool.IMediaReader;
import com.xuggle.mediatool.MediaListenerAdapter;
import com.xuggle.mediatool.ToolFactory;
import com.xuggle.mediatool.event.IVideoPictureEvent;
import com.xuggle.xuggler.Global;
public class ABC {
public static final double SECONDS_BETWEEN_FRAMES = 10;
private static final String inputFilename = "D://ab.mp4";
private static final String outputFilePrefix = "c://snapshots//mysnapshot";
// The video stream index, used to ensure we display frames from one and
// only one video stream from the media container.
private static int mVideoStreamIndex = -1;
// Time of last frame write
private static long mLastPtsWrite = Global.NO_PTS;
public static final long MICRO_SECONDS_BETWEEN_FRAMES =
(long)(Global.DEFAULT_PTS_PER_SECOND * SECONDS_BETWEEN_FRAMES);
public static void main(String[] args) {
IMediaReader mediaReader = ToolFactory.makeReader(inputFilename);
// stipulate that we want BufferedImages created in BGR 24bit color space
mediaReader.setBufferedImageTypeToGenerate(BufferedImage.TYPE_3BYTE_BGR);
mediaReader.addListener(new ImageSnapListener());
// read out the contents of the media file and
// dispatch events to the attached listener
while (mediaReader.readPacket() == null) ;
}
private static class ImageSnapListener extends MediaListenerAdapter {
public void onVideoPicture(IVideoPictureEvent event) {
if (event.getStreamIndex() != mVideoStreamIndex) {
// if the selected video stream id is not yet set, go ahead an
// select this lucky video stream
if (mVideoStreamIndex == -1)
mVideoStreamIndex = event.getStreamIndex();
// no need to show frames from this video stream
else
return;
}
// if uninitialized, back date mLastPtsWrite to get the very first frame
if (mLastPtsWrite == Global.NO_PTS)
mLastPtsWrite = event.getTimeStamp() - MICRO_SECONDS_BETWEEN_FRAMES;
// if it's time to write the next frame
if (event.getTimeStamp() - mLastPtsWrite >=
MICRO_SECONDS_BETWEEN_FRAMES) {
String outputFilename = dumpImageToFile(event.getImage());
// indicate file written
double seconds = ((double) event.getTimeStamp()) /
Global.DEFAULT_PTS_PER_SECOND;
System.out.printf(
"at elapsed time of %6.3f seconds wrote: %s\n",
seconds, outputFilename);
// update last write time
mLastPtsWrite += MICRO_SECONDS_BETWEEN_FRAMES;
}
}
private String dumpImageToFile(BufferedImage image) {
try {
String outputFilename = outputFilePrefix +
System.currentTimeMillis() + ".png";
ImageIO.write(image, "png", new File(outputFilename));
return outputFilename;
}
catch (IOException e) {
e.printStackTrace();
return null;
}
}
}
} -
Subtitling Sierra RBT Files
2 juin 2016, par Multimedia Mike — Game HackingThis is part 2 of the adventure started in my Subtitling Sierra VMD Files post. After I completed the VMD subtitling, The Translator discovered a wealth of animation files in a format called RBT (this apparently stands for “Robot” but I think “Ribbit” format could be more fun). What are we going to do ? We had come so far by solving the VMD subtitling problem for Phantasmagoria. It would be a shame if the effort ground to a halt due to this.
Fortunately, the folks behind the ScummVM project already figured out enough of the format to be able to decode the RBT files in Phantasmagoria.
In the end, I was successful in creating a completely standalone tool that can take a Robot file and a subtitle file and create a new Robot file with subtitles. The source code is here (subtitle-rbt.c). Here’s what the final result looks like :
“What’s in the refrigerator ?” I should note at this juncture that I am not sure if this particular Robot file even has sound or dialogue since I was conducting these experiments on a computer with non-working audio.
The RBT Format
I have created a new MultimediaWiki page describing the Robot Animation format based on the ScummVM source code. I have not worked with a format quite like this before. These are paletted animations which consist of a sequence of independent frames that are designed to be overlaid on top of static background. Because of these characteristics, each frame encodes its own unique dimensions and origin coordinate within the frame. While the Phantasmagoria VMD files are usually 288×144 (which are usually double-sized for the benefit of a 640×400 Super VGA canvas), these frames are meant to be plotted on a game field that was roughly 576×288 (288×144 doublesized).
For example, 2 minimalist animation frames from a desk investigation Robot file :
100×147
101×149As for compression, my first impression was that the algorithm was the same as VMD. This is wrong. It evidently uses an unmodified version of a standard algorithm called Lempel-Ziv-Stac (LZS). It shows up in several RFCs and was apparently used in MS-DOS’s transparent disk compression scheme.
Approach
Thankfully, many of the lessons I learned from the previous project are applicable to this project, including : subtitle library interfacing, subtitling in the paletted colorspace, and replacing encoded frames from the original file instead of trying to create a new file.Here is the pitch for this project :
- Create a C program that can traverse through an input file, piece by piece, and generate an output file. The result of this should be a bitwise identical file.
- Adapt the LZS compression decoding algorithm from ScummVM into the new tool. Make the tool dump raw Portable NetMap (PNM) files of varying dimensions and ensure that they look correct.
- Compress using LZS.
- Stretch the frames and draw subtitles.
- More compression. Find the minimum window for each frame.
Compression
Normally, my first goal is to decompress the video and store the data in a raw form. However, this turned out to be mathematically intractable. While the format does support both compressed and uncompressed frames (even though ScummVM indicates that the uncompressed path is yet unexercised), the goal of this project requires making the frames so large that they overflow certain parameters of the file.A Robot file has a sequence of frames and 2 tables describing the size of each frame. One table describes the entire frame size (audio + video) while the second table describes just the video frame size. Since these tables only use 16 bits to specify a size, the maximum frame size is 65536 bytes. Leaving space for the audio portion of the frame, this only leaves a per-frame byte budget of about 63000 bytes for the video. Expanding the frame to 576×288 (165,888 pixels) would overflow this limit.
Anyway, the upshot is that I needed to compress the data up front.
Fortunately, the LZS compressor is pretty straightforward, at least if you have experience writing VLC-oriented codecs. While the algorithm revolves around back references, my approach was to essentially write an RLE encoder. My compressor would search for runs of data (plentiful when I started to stretch the frame for subtitling purposes). When a run length of n=3 or more of the same pixel is found, encode the pixel by itself, and then store a back reference of offset -1 and length (n-1). It took a little while to iron out a few problems, but I eventually got it to work perfectly.
I have to say, however, that the format is a little bit weird in how it codes very large numbers. The length encoding is somewhat Golomb-like, i.e., smaller values are encoded with fewer bits. However, when it gets to large numbers, it starts encoding counts of 15 as blocks of 1111. For example, 24 is bigger than 7. Thus, emit 1111 into the bitstream and subtract 8 from 23 -> 16. Still bigger than 15, so stuff another 1111 into the bitstream and subtract 15. Now we’re at 1, so stuff 0001. So 24 is 11111111 0001. 12 bits is not too horrible. But the total number of bytes (value / 30). So a value of 300 takes around 10 bytes (80 bits) to encode.
Palette Slices
As in the VMD subtitling project, I took the subtitle color offered in the subtitle spec file as a suggestion and used Euclidean distance to match to the closest available color in the palette. One problem, however, is that the palette is a lot smaller in these animations. According to my notes, for the set of animations I scanned, only about 80 colors were specified, starting at palette index 55. I hypothesize that different slices of the palette are reserved for different uses. E.g., animation, background, and user interface. Thus, there is a smaller number of colors to draw upon for subtitling purposes.Scaling
One bit of residual weirdness in this format is the presence of a per-frame scale factor. While most frames set this to 100 (100% scale), I have observed 70%, 80%, and 90%. ScummVM is a bit unsure about how to handle these, so I am as well. However, I eventually realized I didn’t really need to care, at least not when decoding and re-encoding the frame. Just preserve the scale factor. I intend to modify the tool further to take scale factor into account when creating the subtitle.The Final Resolution
Right around the time that I was composing this post, The Translator emailed me and notified me that he had found a better way to subtitle the Robot files by modifying the scripts, rendering my entire approach moot. The result is much cleaner :
Turns out that the engine supported subtitles all along
It’s a good thing that I enjoyed the challenge or I might be annoyed at this point.
See Also
- Subtitling Sierra VMD Files : My effort to subtitle the main FMV files found in Sierra games.
The post Subtitling Sierra RBT Files first appeared on Breaking Eggs And Making Omelettes.
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How to install ffmpeg for PHP
20 décembre 2016, par Julie BsdI’ve successfully installed ffmpeg using ssh, as root, on my dedicated server (CentOS 7).
ffmpeg works fine - but now I need to use it without root access.When i try to use ffmpeg without root access, I get the following error :
ffmpeg: error while loading shared libraries: libx264.so.148:
cannot open shared object file: No such file or directoryThe final goal is to be able to use ffmpeg inside my PHP scripts which do not root access.