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• H.264 and VP8 for still image coding : WebP ?

  
  1er octobre 2010, par Dark Shikari — google, H.264, psychovisual optimizations, VP8

  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]

• Podcast Producer 2 REST api

  11 septembre 2009

  I’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>

• Q&A : An interview with Matomo founder, Matthieu Aubry

  20 novembre 2018, par Joselyn Khor — About, Community

  Hey everyone ! Joselyn here. As always the views of our community remain top of mind. So to make sure you guys know the thinking behind these new projects, we reached out to Matomo’s founder, Matthieu, to ask questions you might want answered. Please check it out below !

  Hi guys, it’s Matthieu ! Here to answer some questions about the rebrand and the future of Matomo and Innocraft.

  What’s upcoming ?

  We’ve been busy implementing our rebrand into all aspects of Matomo and there’s also our new website, which is launching today ! The new website will help people better understand what Matomo is and how they can benefit from using modern web analytics.

  Why was Matomo and Innocraft brought onto one website ?

  In the past the separation caused a bit of confusion so we’re taking this as a chance to unite both the business brand, Innocraft and community brand, Matomo, on one website. Putting our focus on one brand, Matomo, makes it easier for people to see us with fresh eyes. We have a community side as well as a business side and while the community is still incredibly important to us, we find we have a powerful analytics tool that is capable of helping businesses too.

  Is Matomo becoming commercial or turning corporate ?

  No. nothing is changing. Matomo is still an open-source project and community. Although we’ll have a pricing page and “start free trial” on the new website brought over from Innocraft.cloud, the Matomo community will still play the biggest part on the Matomo website. We have dedicated sections focused on Community and On-Premise.

  The rebrand exercise helped us gain a refreshed perspective. After reflecting on how far we’ve come, we can feel more confident about Matomo Analytics itself as a platform. We believe it’s a great chance to bring that confidence into the brand and vision. We are proud that it’s an awesome open-source platform and at the same time it’s also powerful as a tool for businesses.

  Why is there no ‘download for free’ button on the homepage ?

   

  
  We feel many users coming to the site will get confused about our hosting options (Cloud and On-Premise) which is something you don’t usually consider when choosing an analytics tool.

  The reason for us to not have that button is when people see a “download for free” button on the homepage next to a “try it for free” button, it creates confusion. For those who do choose to download Matomo often become confused when they are left with a .zip file unaware how to install it and the technical requirements of self-hosting. We feel presenting our users with the simplest installation option first will give them the best chance possible to try Matomo to its full potential, without cost.

  And you can still find the link to Download Matomo in the footer of each page.
  

   

  Is Matomo still free to download and have forever ?

  Absolutely. The free open-source download can be found on the On-Premise section of the website, or download Matomo here.

  Why is it important to have a business behind the project ?

  There’s the reality that we have to make money in order for the Matomo project to survive … and thrive. The reason we still need a business side (Innocraft) is to fund and sustain the Matomo project. Whenever people purchase premium features, this helps finance the development of Matomo for our community.

  Because of the business we’re able to continually maintain and develop Matomo for you guys as well as future users. For example, the next release Matomo 3.8.0 is already mostly developed and will bring lots of interesting features too, like the two-factor authentication, Brute Force Protection, failed tracking requests reporting, lots of JavaScript tracker improvements, a new total summary row below reports, and many more security fixes, bug fixes, and other new features.

  So we see a business being very helpful in supporting our open-source community. Without a business side, our free, open-source project would not be able to survive.

  How will you protect the Matomo project ?

  We’ve ensured the Matomo project will be protected for the future as we wish to turn it into a not-for-profit foundation.

  We’ve also got a safeguard where the open-source code will stay under a GPL license forever. This is so we can guarantee, that no matter what happens, the Matomo project itself will stay completely free software.

  Is there a way for people to help ?

  There are heaps of ways to help ! You can help other Matomo users in the forums, contribute to fixes on GitHub, leave a great review (e.g. alternativeTo), help look for bugs with our Security Bounty Programme or participate and spread the word about Matomo in our community social media pages – Mastodon, Facebook, Twitter. Telling your friends about us would be very helpful too !

  What’s planned for the future ?
  We’ve worked hard to become the #1 open-source analytics platform (1.4 million websites use Matomo today), but now we need to empower even more individuals and businesses to take back control of their own data.

  Showing our community that we have a powerful platform is crucial, but alongside that our values are what define us. User privacy is still of utmost importance and we’re here to make it known that power needs to rest in the hands of people and not large corporations.

  You can rest easy knowing you’re doing your part in using trustworthy and dependable tools. By joining many other companies who are growing this movement to decentralise the Internet, we can build a safer, online world together.

  Join this analytics revolution and let us know what you think about Matomo !