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• FFmpeg noise reduction for live broadcast

  4 décembre 2019, par Vsevolod Trofimov

  Now we use FFmpeg for live broadcast to youtube with following options :
  ffmpeg -i "rtsp ://xxx" -vcodec libx264 -t $duration -pix_fmt + -c:v copy -acodec libmp3lame -af "afftdn=nt=w" -ar 44100 -threads 6 -qscale 3 -b:a 712000 -bufsize 512k -f flv

  for webinars in our university. what is the best way (FFmpeg filters/option) of background noise reduction in live broadcast ? We need only voice on output, no music.

  Noise sources are : outdoor noise, projectors and computer noise, students, electrical noises in ip camera’s audiocard.

• 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

• AppRTC : Google’s WebRTC test app and its parameters

  23 juillet 2014, par silvia

  If you’ve been interested in WebRTC and haven’t lived under a rock, you will know about Google’s open source testing application for WebRTC : AppRTC.

  When you go to the site, a new video conferencing room is automatically created for you and you can share the provided URL with somebody else and thus connect (make sure you’re using Google Chrome, Opera or Mozilla Firefox).

  We’ve been using this application forever to check whether any issues with our own WebRTC applications are due to network connectivity issues, firewall issues, or browser bugs, in which case AppRTC breaks down, too. Otherwise we’re pretty sure to have to dig deeper into our own code.

  Now, AppRTC creates a pretty poor quality video conference, because the browsers use a 640×480 resolution by default. However, there are many query parameters that can be added to the AppRTC URL through which the connection can be manipulated.

  Here are my favourite parameters :
  

  • hd=true : turns on high definition, ie. minWidth=1280,minHeight=720
  • stereo=true : turns on stereo audio
  • debug=loopback : connect to yourself (great to check your own firewalls)
  • tt=60 : by default, the channel is closed after 30min – this gives you 60 (max 1440)

  For example, here’s how a stereo, HD loopback test would look like : https://apprtc.appspot.com/?r=82313387&hd=true&stereo=true&debug=loopback .

  This is not the limit of the available parameter, though. Here are some others that you may find interesting for some more in-depth geekery :

  • ss=[stunserver] : in case you want to test a different STUN server to the default Google ones
  • ts=[turnserver] : in case you want to test a different TURN server to the default Google ones
  • tp=[password] : password for the TURN server
  • audio=true&video=false : audio-only call
  • audio=false : video-only call
  • audio=googEchoCancellation=false,googAutoGainControl=true : disable echo cancellation and enable gain control
  • audio=googNoiseReduction=true : enable noise reduction (more Google-specific parameters)
  • asc=ISAC/16000 : preferred audio send codec is ISAC at 16kHz (use on Android)
  • arc=opus/48000 : preferred audio receive codec is opus at 48kHz
  • dtls=false : disable datagram transport layer security
  • dscp=true : enable DSCP
  • ipv6=true : enable IPv6

  AppRTC’s source code is available here. And here is the file with the parameters (in case you want to check if they have changed).

  Have fun playing with the main and always up-to-date WebRTC application : AppRTC.

  UPDATE 12 May 2014

  AppRTC now also supports the following bitrate controls :

  • arbr=[bitrate] : set audio receive bitrate
  • asbr=[bitrate] : set audio send bitrate
  • vsbr=[bitrate] : set video receive bitrate
  • vrbr=[bitrate] : set video send bitrate

  Example usage : https://apprtc.appspot.com/?r=&asbr=128&vsbr=4096&hd=true