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• The First Problem

  19 janvier 2011, par Multimedia Mike — HTML5

  A few years ago, The Linux Hater made the following poignant observation regarding Linux driver support :

  Drivers are only just the beginning... But for some reason y’all like to focus on the drivers. You know why lusers do that ? Because it just happens to be the problem that people notice first.

  And so it is with the HTML5 video codec debate, re-invigorated in the past week by Google’s announcement of dropping native H.264 support in their own HTML5 video tag implementation. As I read up on the fiery debate, I kept wondering why people are so obsessed with this issue. Then I remembered the Linux Hater’s post and realized that the video codec issue is simply the first problem that most people notice regarding HTML5 video.

  I appreciate that the video codec debate has prompted Niedermayer to post on his blog once more. Otherwise, I’m just munching popcorn on the sidelines, amused and mildly relieved that the various factions are vociferously attacking each other rather than that little project I help with at work.

  Getting back to the "first problem" aspect— there’s so much emphasis on the video codec ; I wonder why no one ever, ever mentions word one about an audio codec. AAC is typically the codec that pairs with H.264 in the MPEG stack. Dark Shikari once mentioned that "AAC’s licensing terms are exponentially more onerous than H.264′s. If Google didn’t want to use H.264, they would sure as hell not want to use AAC." Most people are probably using "H.264" to refer to the entire MPEG/H.264/AAC stack, even if they probably don’t understand what all of those pieces mean.

  Anyway, The Linux Hater’s driver piece continues :

  Once y’all have drivers, the fight will move to the next layer up. And like I said, it’s a lot harder at that layer.

  A few months ago, when I wanted to post the WebM output of my new VP8 encoder and thought it would be a nice touch to deliver it via a video tag, I ignored the video codec problem (just encoded a VP8/WebM file) only to immediately discover a problem at a different layer— specifically, embedding a file using a video tag triggers a full file download when the page is loaded, which is unacceptable from end user and web hosting perspectives. This is a known issue but doesn’t get as much attention, I guess because there are bigger problems to solve first (c.f. video codec issue).

  For other issues, check out the YouTube blog’s HTML5 post or Hulu’s post that also commented on HTML5. Issues such as video streaming flexibility, content protection, fullscreen video, webcam/microphone input, and numerous others are rarely mentioned in the debates. Only "video codec" is of paramount importance.

  But I’m lending too much weight to the cacophony of a largely uninformed internet debate. Realistically, I know there are many talented engineers down in the trenches working to solve at least some of these problems. To tie this in with the Linux driver example, I’m consistently stunned these days regarding how simple it is to get Linux working on a new computer— most commodity consumer hardware really does just work right out of the box. Maybe one day, we’ll wake up and find that HTML5 video has advanced to the point that it solves all of the relevant problems to make it the simple and obvious choice for delivering web video in nearly all situations.

  It won’t be this year.

• FFmpeg Libraries : How Do I Convert a Video to 4 Level Grayscale Video at 160x100 Pixels and as Raw Data

  15 avril 2014, par pimathbrainiac

  This seems like an odd question, so I am going to start from the beginning :

  I am a calculator programmer, specifically a Ti-89 programmer, and I'm trying to make a video player for it. I have the code for the calculator side done already, but I need to be able to convert video to a specific format that works as follows :

  Each frame is 4 level grayscale, where there are 2 bytes for every 8 horizontal pixels, a "back," or dark byte, and a "front," or light byte. Basically, every frame is 2 monochrome binary images, with the first byte of the first one is followed by the first byte of the second one, so data is stored as follows :

  FB(front buffer)[1],BB(back buffer)[1],FB[2],BB[2], etc...

  Here's how the display works : (defining 0 as white and 3 as black, with 1 and 2 being in-between shades)
  Each front buffer bit is worth 1, so if the front buffer were displayed with nothing in the back buffer, the "1" (or true) bits would show up as light gray pixels. These are then added to the back buffer bits, which are worth 2 (so if the back buffer were displayed with nothing in the front buffer, the "1" (or true) bits would show up as dark gray pixels) to get :

  "0" bit on either buffer = white pixel (0+0=0)

  "1" bit on front buffer but not back buffer = light gray pixel (1+0=1)

  "1" bit on back buffer but not front buffer = dark gray pixel (0+2=2)

  "1" bit on both buffers = black pixel (1+2=3)

  I have this down calculator-side, but I need to know : 1) How to convert the video to a specific framerate using the libs 2) How to convert these frames to 4-level grayscale at 160x100 pixels and 3) How to save these frames as raw data in the format I described. Thank you in advance for your answer(s).

• Your guide to cookies, web analytics, and GDPR compliance

  25 février 2020, par Joselyn Khor — Analytics Tips, Privacy, Security
  It’s been almost two years since the GDPR came into effect and turned the online world on its head. Confusion around cookies/cookie consent/cookie compliance remains till today. So we’d like to take this chance to talk more about the supposed “big bad” of the latest century. 

  Online cookies seem to have a bad reputation, but are they as bad as they seem ?

  To start, what are cookies on the internet ?

  An internet cookie a.k.a. an HTTP cookie, is a small piece of data sent from websites that is stored on your computer or mobile when you visit that site.

  Are all cookies bad ?

  No. Cookies themselves are usually harmless as they can’t infect computers with malware. 

  They can also be helpful for both websites who use them and individuals visiting those websites. For example, when online shopping, cookies on ecommerce sites keep track of what you’re shopping for. If you didn’t have that tracking, your cart would be empty every time you moved away from that site.

  For businesses/websites, cookies can be used for authentication (logins) and tracking website user experience. For example, tracking multiple visits to the same site in order to provide better experiences to customers visiting their website.

  

  The not-so-sweet types of cookies :

  Cookies that contain personal data

  Another example of a bad cookie is when cookies contain personal data directly in the cookie itself. For example, when websites store demographics or your name in a cookie ; or when a website stores survey results in a cookie. Use of cookies in these ways is considered bad practice nowadays.

  Third-party cookies
  

  They can be used by websites to learn about your visit and activity across multiple websites. Cookies can enter harmful territory when employed for “big brother” types of tracking i.e. when they’re used to build a virtual fingerprint of individuals after their activity is tracked from website to website. For example most advertising networks create third party cookies in your browser when you view an ad, which lets these advertisers track users across these websites and let companies buy more targeted ads.

  Why does Matomo use cookies ?

  

  For accurate reporting of new and returning visitors. Matomo uses cookies to store some information about visitors between visits. We also use cookies to remember if someone gave consent to tracking, or opted out of tracking. 

  Types of cookies Matomo uses :

  • Matomo by default uses first-party cookies, set on the domain of your site.
  • Cookies created by Matomo start with : _pk_ref, _pk_cvar, _pk_id, _pk_ses. See a list of all Matomo cookies : https://matomo.org/faq/general/faq_146/

  Cookie-less tracking - disable cookies and ensure cookie compliance :

  It’s possible to disable tracking cookies in Matomo by adding a line on the javascript code. When cookies are disabled, Matomo data will become slightly less accurate. Also, when cookies are disabled, there may still be a few cookies created in specific cases.

  If you disable cookies, Matomo tries to detect unique visitors by a fingerprint based on a few browser attributes : operating system, browser, browser plugins, IP address and browser language.

  By disabling tracking cookies, you may also use Matomo without needing to display a cookie consent screen. You can also keep tracking when they reject cookie consent by keeping cookies disabled.

  Cookies and the GDPR

  In some countries and according to the GDPR, websites need to provide a way for users to opt-out of all tracking, in particular tracking cookies.

  The GDPR regulates the use of cookies when they compromise an individual’s privacy. When cookies can identify an individual, it is considered personal data.

  

  Cookie compliance and the GDPR

  To be GDPR compliant you must :

  • Receive user consent before using any cookies (except strictly necessary cookies). Read more on cookies that are “clearly exempt from consent”.
  • Provide accurate and specific information about the data each cookie tracks and its purpose in plain language before consent is received.
  • Document and store consent received from users.
  • Allow users to access your service even if they refuse to allow the use of certain cookies
  • Make it as easy for users to withdraw their consent as it was for them to give their consent in the first place.

  Source : https://gdpr.eu/cookies/

  When does GDPR require cookie consent ?

  The purpose of the GDPR is to give individuals control over their personal data. As such this regulation has provisions and requirements which regulate the processing of personal data to protect the privacy of individuals. 

  This means in order to use cookies, you will sometimes need explicit consent from those individuals.

  When does GDPR not require cookie consent ?

  Then there are many cookies that generally do NOT require consent (Source : https://wikis.ec.europa.eu/display/WEBGUIDE/04.+Cookies). 

  These are :

  • user input cookies, for the duration of a session
  • authentication cookies, for the duration of a session
  • user-centric security cookies, used to detect authentication abuses and linked to the functionality explicitly requested by the user, for a limited persistent duration
  • multimedia content player session cookies, such as flash player cookies, for the duration of a session
  • load balancing session cookies and other technical cookies, for the duration of session
  • user interface customisation cookies, for a browser session or a few hours, when additional information in a prominent location is provided (e.g. “uses cookies” written next to the customisation feature)

  Tracking cookies and consent vs legitimate interest

  

  User consent is not always required :

  We understand that whenever you collect and process personal data, you need – almost always – to ask for their consent. However, there are instances where you have to process data under “legitimate interests”. The GDPR states that processing of personal data is lawful “if processing is necessary for the purposes of the legitimate interests”. This means if you have “legitimate interests” you can avoid asking for consent for collecting and processing personal information. Learn more : https://cookieinformation.com/resources/blog/what-is-legitimate-interest-under-the-gdpr 

  A lawful basis for processing personal data (proceeding with caution) :

  We’ve also written about having a lawful basis for processing personal data under GDPR with Matomo. The caveat here is you need to have a strong argument for legitimate interests. If you are processing personal data which may represent a risk to the final user, then getting consent is, for us, still the right lawful basis. If you are not sure, at the time of writing ICO is providing a tool in order to help you make this decision.

  How is Matomo Analytics GDPR compliant ?

  Matomo can be configured to automatically anonymise data so you don’t process any personal data. This allows you to completely avoid GDPR. If you decide to process personal data, Matomo provides you with 12 steps to easily comply with the GDPR guidelines.

  New developments on cookies and the GDPR

  In the early days of the GDPR, a spate of cookie management platforms (CMPs) popped up to help websites and people comply with GDPR rules around cookies.

  These have become problematic in recent years. Europe’s highest court ruled pre-checked box for cookie boxes does not give enough consent. 

  As well as that, new research suggests most cookie consent pop-ups in the EU fall short of GDPR. A new study called, ‘Dark Patterns after the GDPR’ from MIT, UCL and Aarhus University found that a vast majority of websites aren’t following GDPR rules around cookies. The study found most cookie consent pop-ups in the EU to be undermining the GDPR by finding sneaky ways to convince website visitors to click ‘accept’.

  Disclaimer

  We are not lawyers and don’t claim to be. The information provided here is to help give an introduction to issues you may encounter when dealing cookies. We encourage every business and website to take data privacy seriously and discuss these issues with your lawyer if you have any concerns. 

  Additional resources :

  • How do the cookie rules relate to the GDPR ? 
  • Cookies, the GDPR, and the ePrivacy Directive