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Demon Seed
26 septembre 2011, par
Mis à jour : Septembre 2011
Langue : English
Type : Audio
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Demon seed (wav version)
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Mis à jour : Avril 2013
Langue : English
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The four of us are dying (wav version)
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Mis à jour : Avril 2013
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26 septembre 2011, par
Mis à jour : Avril 2013
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26 septembre 2011, par
Mis à jour : Avril 2013
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Autres articles (61)
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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 (...) -
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. -
MediaSPIP Player : problèmes potentiels
22 février 2011, parLe lecteur ne fonctionne pas sur Internet Explorer
Sur Internet Explorer (8 et 7 au moins), le plugin utilise le lecteur Flash flowplayer pour lire vidéos et son. Si le lecteur ne semble pas fonctionner, cela peut venir de la configuration du mod_deflate d’Apache.
Si dans la configuration de ce module Apache vous avez une ligne qui ressemble à la suivante, essayez de la supprimer ou de la commenter pour voir si le lecteur fonctionne correctement : /** * GeSHi (C) 2004 - 2007 Nigel McNie, (...)
Sur d’autres sites (6937)
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Q&A : An interview with Matomo founder, Matthieu Aubry
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Podcast Producer 2 REST api
11 septembre 2009I’ve been working on documenting the REST api that PCP2 uses for client server communication as part of a new project. I thought it might be useful to other folks. Consider this a work in progress - I’ve only documented the workflow for doing a multisource recording so far. Follow the job for the info.
Each section gives a sample command and a sample response.
All pages are behind basic HTTP auth.
General sequence of events
* get workflow list
* get cameras
* request status for camera (including thumbnail)
* start cameras
* create recording enclosure
* stop cameras, provide submission_UUID returned by above step, include title
*URL : https://pcpserver:8170/podcastproducer/info
*Type : GET
*Content : version=2
*Response :
<pre>
<podcast_producer_result>
<action>index</action>
<status>success</status>
<plist version="1.0">
<dict>
<key>server_version</key>
<string>2.0</string>
<key>http_auth_type</key>
<array>
<string>basic</string>
<string>digest</string>
<string>kerberos</string>
</array>
<key>krb_service_principals</key>
<array>
<string>pcast/x101-186-103-dhcp.cla.umn.edu@X101-186-103-DHCP.CLA.UMN.EDU</string>
</array>
<key>server_uuid</key>
<string>DB31DA49-10AE-472C-B3B9-86A8F8112399</string>
<key>cluster_members</key>
<dict>
<key>F1021B98-7E7E-44FB-8EB1-E0DA1885D5BA</key>
<dict>
<key>date_added</key>
<string>Tue Sep 01 10:23:49 -0500 2009</string>
<key>last_update</key>
<string>Tue Sep 08 10:35:17 -0500 2009</string>
<key>server_host</key>
<string>x101-186-103-dhcp.cla.umn.edu</string>
<key>server_port</key>
<string>8170</string>
<key>tunnel_agent_host</key>
<string>x101-186-103-dhcp.cla.umn.edu</string>
<key>tunnel_agent_port</key>
<string>8175</string>
<key>network_addrs</key>
<array>
<string>128.101.186.103</string>
</array>
</dict>
</dict>
</dict>
</plist>
</podcast_producer_result>
</pre>
* URL : https://pcpserver:8170/podcastproducer/workflows
* Type : GET
* Content : version=2&language=en
* Response :
<pre>
<podcast_producer_result>
<action>index</action>
<status>success</status>
<results>OK</results>
<plist version="1.0">
<dict>
<key>user_fullname</key>
<string>podcast</string>
<key>user_shortname</key>
<string>podcast</string>
<key>workflows</key>
<array>
<dict>
<key>name</key>
<string>Montage</string>
<key>title</key>
<string>Montage</string>
<key>description</key>
<string>Montage workflow</string>
<key>uuid</key>
<string>F797D54D-1539-42AA-B6AC-3CB3A4C15EF5</string>
<key>version</key>
<string>2.0</string>
<key>editor</key>
<string>Podcast Composer</string>
<key>sources</key>
<array>
<dict>
<key>contentTypes</key>
<array>
<string>com.apple.quicktime-movie</string>
<string>com.adobe.pdf</string>
<string>com.apple.iwork.keynote.key</string>
<string>com.apple.iwork.pages.pages</string>
<string>org.openxmlformats.wordprocessingml.document</string>
<string>com.microsoft.word.doc</string>
<string>org.openxmlformats.presentationml.presentation</string>
<string>com.microsoft.powerpoint.ppt</string>
<string>com.microsoft.bmp</string>
<string>com.compuserve.gif</string>
<string>public.jpeg-2000</string>
<string>public.jpeg</string>
<string>com.adobe.pdf</string>
<string>com.apple.pict</string>
<string>public.png</string>
<string>com.adobe.photoshop-image</string>
<string>com.sgi.sgi-image</string>
<string>com.truevision.tga-image</string>
<string>public.tiff</string>
</array>
<key>description</key>
<string>Any Document</string>
<key>isFolder</key>
<true/>
<key>isOptional</key>
<false/>
<key>sourceTypes</key>
<array>
<string>File</string>
</array>
</dict>
</array>
<key>user_requirements</key>
<array>
<string>Title</string>
<string>Description</string>
</array>
<key>access_control_entries</key>
<array>
</array>
</dict>
<dict>
<key>name</key>
<string>Single Source</string>
<key>title</key>
<string>Single Source</string>
<key>description</key>
<string>Single Source workflow</string>
<key>uuid</key>
<string>DEFA1587-A650-426E-92DA-01C5EB811705</string>
<key>version</key>
<string>2.0</string>
<key>editor</key>
<string>Podcast Composer</string>
<key>sources</key>
<array>
<dict>
<key>contentTypes</key>
<array>
<string>com.apple.quicktime-movie</string>
</array>
<key>description</key>
<string>Any Video</string>
<key>isFolder</key>
<false/>
<key>isOptional</key>
<false/>
<key>sourceTypes</key>
<array>
<string>Video</string>
<string>Screen</string>
<string>Audio</string>
<string>File</string>
</array>
</dict>
</array>
<key>user_requirements</key>
<array>
<string>Title</string>
<string>Description</string>
</array>
<key>access_control_entries</key>
<array>
</array>
</dict>
</array>
</dict>
</plist>
</podcast_producer_result>
</pre>
----* URL : https://pcpserver:8170/podcastproducer/cameras
* Type : GET
* Content : version=2
* Response :
<pre>
<podcast_producer_result>
<action>index</action>
<status>success</status>
<plist version="1.0">
<dict>
<key>cameras</key>
<array>
<dict>
<key>name</key>
<string>150-A Camera</string>
<key>uuid</key>
<string>307682A5-B552-4AFA-B7E2-3811D772C9A1</string>
<key>connected_to_member_uuid</key>
<string>F1021B98-7E7E-44FB-8EB1-E0DA1885D5BA</string>
<key>in_use</key>
<string>false</string>
<key>recording_status</key>
<string>online</string>
<key>preview_url</key>
<string>https://x101-186-103-dhcp.cla.umn.edu:8170/podcastproducer/previews/307682A5-B552-4AFA-B7E2-3811D772C9A1.jpg</string> ;
<key>access_control_entries</key>
<array>
</array>
</dict>
<dict>
<key>name</key>
<string>150-A Epiphan</string>
<key>uuid</key>
<string>CE610AB0-CA50-49EB-8FFE-78E57CDCA550</string>
<key>connected_to_member_uuid</key>
<string>F1021B98-7E7E-44FB-8EB1-E0DA1885D5BA</string>
<key>in_use</key>
<string>false</string>
<key>recording_status</key>
<string>online</string>
<key>preview_url</key>
<string>https://x101-186-103-dhcp.cla.umn.edu:8170/podcastproducer/previews/CE610AB0-CA50-49EB-8FFE-78E57CDCA550.jpg</string> ;
<key>access_control_entries</key>
<array>
</array>
</dict>
</array>
</dict>
</plist>
</podcast_producer_result>
</pre>
* URL : https://pcpserver:8170/podcastproducer/cameras/start
* Type : POST
* Content : action=pause&version=2&camera_name=150-A%20Camera&controller=cameras
* Response :
<pre>
<podcast_producer_result>
<action>start</action>
<status>success</status>
<results>OK</results>
</podcast_producer_result>
</pre>
* URL : https://pcpserver:8170/podcastproducer/cameras/status
* Type : POST
* Content : delay=0&action=start&version=2&camera_name=150-A%20Epiphan&controller=cameras
* Response :
<pre><podcast_producer_result>
<action>status</action>
<status>success</status>
<results>OK</results>
<plist version="1.0">
<dict>
<key>preview</key>
<string>https://x101-186-103-dhcp.cla.umn.edu:8170/podcastproducer/previews/307682A5-B552-4AFA-B7E2-3811D772C9A1.jpg</string> ;
<key>preview_image_data</key>
<string>RAW JPEG DATA RAW JPEG DATA RAW JPEG DATA RAW JPEG DATA RAW JPEG DATA</string>
<key>recording_status</key>
<string>online</string>
<key>started_at</key>
<string>Tue Sep 08 09:31:40 -0500 2009</string>
<key>stopped_at</key>
<string>Tue Sep 08 09:32:10 -0500 2009</string>
<key>elapsed</key>
<string>41</string>
<key>last_error</key>
<string>805306368</string>
</dict>
</plist>
</podcast_producer_result>
</pre>
* URL : https://pcpserver:8170/podcastproducer/cameras/pause
* Type : POST
* Content : action=pause&version=2&camera_name=150-A%20Camera&controller=cameras
* Response :
<pre><podcast_producer_result>
<action>status</action>
<status>success</status>
<results>OK</results>
<plist version="1.0">
<dict>
<key>preview</key>
<string>https://x101-186-103-dhcp.cla.umn.edu:8170/podcastproducer/previews/307682A5-B552-4AFA-B7E2-3811D772C9A1.jpg</string> ;
<key>recording_status</key>
<string>online</string>
<key>started_at</key>
<string>Tue Sep 08 09:31:40 -0500 2009</string>
<key>stopped_at</key>
<string>Tue Sep 08 09:32:10 -0500 2009</string>
<key>elapsed</key>
<string>41</string>
<key>last_error</key>
<string>805306368</string>
</dict>
</plist>
</podcast_producer_result></pre>
* URL : https://pcpserver:8170/podcastproducer/cameras/stop
* Type : POST
* Content : workflow_name=&UserMetadata_Description=&submission_uuid=7497E3AC-0A75-4C7C-8C66-26294C9274FE&action=stop&version=2&camera_name=150-A%20Epiphan&controller=cameras&UserMetadata_Title=Test123
* Response :
<pre><podcast_producer_result>
<action>stop</action>
<status>success</status>
<results>OK</results>
</podcast_producer_result>
</pre>
* URL : https://pcpserver:8170/podcastproducer/recordings/create
* Type : POST
* Content : version=2&workflow_uuid=C6EF52A7-04E3-477D-9F38-6B61F108D7B9
* Response :
<pre>
<podcast_producer_result>
<action>create</action>
<status>success</status>
<results>OK</results>
<plist version="1.0">
<dict>
<key>workflow_uuid</key>
<string>C6EF52A7-04E3-477D-9F38-6B61F108D7B9</string>
<key>recording_uuid</key>
<string>FD5A1459-F7CE-41FA-8155-049DF774298B</string>
<key>submission_uuids</key>
<array>
<string>A626D8E4-E439-4E57-9982-DB4BD035CB41</string>
<string>CFBCCB74-A41F-42D3-BEAA-58165B1116C6</string>
</array>
</dict>
</plist>
</podcast_producer_result>
</pre> -
H.264 and VP8 for still image coding : WebP ?
Update : post now contains a Theora comparison as well ; see below.
JPEG is a very old lossy image format. By today’s standards, it’s awful compression-wise : practically every video format since the days of MPEG-2 has been able to tie or beat JPEG at its own game. The reasons people haven’t switched to something more modern practically always boil down to a simple one — it’s just not worth the hassle. Even if JPEG can be beaten by a factor of 2, convincing the entire world to change image formats after 20 years is nigh impossible. Furthermore, JPEG is fast, simple, and practically guaranteed to be free of any intellectual property worries. It’s been tried before : JPEG-2000 first, then Microsoft’s JPEG XR, both tried to unseat JPEG. Neither got much of anywhere.
Now Google is trying to dump yet another image format on us, “WebP”. But really, it’s just a VP8 intra frame. There are some obvious practical problems with this new image format in comparison to JPEG ; it doesn’t even support all of JPEG’s features, let alone many of the much-wanted features JPEG was missing (alpha channel support, lossless support). It only supports 4:2:0 chroma subsampling, while JPEG can handle 4:2:2 and 4:4:4. Google doesn’t seem interested in adding any of these features either.
But let’s get to the meat and see how these encoders stack up on compressing still images. As I explained in my original analysis, VP8 has the advantage of H.264′s intra prediction, which is one of the primary reasons why H.264 has such an advantage in intra compression. It only has i4x4 and i16x16 modes, not i8x8, so it’s not quite as fancy as H.264′s, but it comes close.
The test files are all around 155KB ; download them for the exact filesizes. For all three, I did a binary search of quality levels to get the file sizes close. For x264, I encoded with
--tune stillimage --preset placebo
. For libvpx, I encoded with--best
. For JPEG, I encoded with ffmpeg, then applied jpgcrush, a lossless jpeg compressor. I suspect there are better JPEG encoders out there than ffmpeg ; if you have one, feel free to test it and post the results. The source image is the 200th frame of Parkjoy, from derf’s page (fun fact : this video was shot here ! More info on the video here.).Files : (x264 [154KB], vp8 [155KB], jpg [156KB])
Results (decoded to PNG) : (x264, vp8, jpg)
This seems rather embarrassing for libvpx. Personally I think VP8 looks by far the worst of the bunch, despite JPEG’s blocking. What’s going on here ? VP8 certainly has better entropy coding than JPEG does (by far !). It has better intra prediction (JPEG has just DC prediction). How could VP8 look worse ? Let’s investigate.
VP8 uses a 4×4 transform, which tends to blur and lose more detail than JPEG’s 8×8 transform. But that alone certainly isn’t enough to create such a dramatic difference. Let’s investigate a hypothesis — that the problem is that libvpx is optimizing for PSNR and ignoring psychovisual considerations when encoding the image… I’ll encode with
--tune psnr --preset placebo
in x264, turning off all psy optimizations.Files : (x264, optimized for PSNR [154KB]) [Note for the technical people : because adaptive quantization is off, to get the filesize on target I had to use a CQM here.]
Results (decoded to PNG) : (x264, optimized for PSNR)
What a blur ! Only somewhat better than VP8, and still worse than JPEG. And that’s using the same encoder and the same level of analysis — the only thing done differently is dropping the psy optimizations. Thus we come back to the conclusion I’ve made over and over on this blog — the encoder matters more than the video format, and good psy optimizations are more important than anything else for compression. libvpx, a much more powerful encoder than ffmpeg’s jpeg encoder, loses because it tries too hard to optimize for PSNR.
These results raise an obvious question — is Google nuts ? I could understand the push for “WebP” if it was better than JPEG. And sure, technically as a file format it is, and an encoder could be made for it that’s better than JPEG. But note the word “could”. Why announce it now when libvpx is still such an awful encoder ? You’d have to be nuts to try to replace JPEG with this blurry mess as-is. Now, I don’t expect libvpx to be able to compete with x264, the best encoder in the world — but surely it should be able to beat an image format released in 1992 ?
Earth to Google : make the encoder good first, then promote it as better than the alternatives. The reverse doesn’t work quite as well.
Addendum (added Oct. 2, 03:51) :
maikmerten gave me a Theora-encoded image to compare as well. Here’s the PNG and the source (155KB). And yes, that’s Theora 1.2 (Ptalarbvorm) beating VP8 handily. Now that is embarassing. Guess what the main new feature of Ptalarbvorm is ? Psy optimizations…
Addendum (added Apr. 20, 23:33) :
There’s a new webp encoder out, written from scratch by skal (available in libwebp). It’s significantly better than libvpx — not like that says much — but it should probably beat JPEG much more readily now. The encoder design is rather unique — it basically uses K-means for a large part of the encoding process. It still loses to x264, but that was expected.
[155KB]