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• How to compress webcam videos recorded by html5 MediaRecorder api ?

  19 mai 2017, par JasonY

  I successfully recorded my webcam using MediaRecorder api and the resulting filesizes seemed far too big for their quality.

  For example, for an 8 second video that was 480x640 I got a 1mB file size. That does not seem right.

  My code to record()

  navigator.mediaDevices.getUserMedia({video: true, audio: true})
  
      .then(function(stream){
  
          var options = {
  
              mimeType : "video/webm;codecs=vp9"
  
              //I don't set bitrate here even if I do the quality is too bad
  
          }
  
          var media_recorder = new MediaRecorder(media_stream, options);
  
          var recorded_data = [];
  
          media_recorder.ondataavailable = function(e){
  
               recorded_data.push(e.data);
  
          }
  
          media_recorder.onstop = function(e){
  
              recorded_data.push(e.data);
  
              var recorded_blob = new Blob(recorded_data, { 'type' : 'video/webm; codecs=vp9' });
  
              var recorded_video_url = window.URL.createObjectURL(recorded_blob);
  
              //here I write some code to download the blob from this url through a href
  
          }
  
      })

  The file obtained by this method is unreasonably large which makes me wonder if it was even compressed when encoded by VP9 ? A 7 second video is about 870kB !

  Inspecting the file with a mediainfo tool gives me

  General
  
  Count                                    : 323
  
  Count of stream of this kind             : 1
  
  Kind of stream                           : General
  
  Kind of stream                           : General
  
  Stream identifier                        : 0
  
  Count of video streams                   : 1
  
  Count of audio streams                   : 1
  
  Video_Format_List                        : VP9
  
  Video_Format_WithHint_List               : VP9
  
  Codecs Video                             : V_VP9
  
  Video_Language_List                      : English
  
  Audio_Format_List                        : Opus
  
  Audio_Format_WithHint_List               : Opus
  
  Audio codecs                             : Opus
  
  Audio_Language_List                      : English
  
  Complete name                            : recorded_video.webm
  
  File name                                : recorded_video
  
  File extension                           : webm
  
  Format                                   : WebM
  
  Format                                   : WebM
  
  Format/Url                               : http://www.webmproject.org/
  
  Format/Extensions usually used           : webm
  
  Commercial name                          : WebM
  
  Format version                           : Version 2
  
  Internet media type                      : video/webm
  
  Codec                                    : WebM
  
  Codec                                    : WebM
  
  Codec/Url                                : http://www.webmproject.org/
  
  Codec/Extensions usually used            : webm
  
  File size                                : 867870
  
  File size                                : 848 KiB
  
  File size                                : 848 KiB
  
  File size                                : 848 KiB
  
  File size                                : 848 KiB
  
  File size                                : 847.5 KiB
  
  File last modification date              : UTC 2017-05-19 05:48:00
  
  File last modification date (local)      : 2017-05-19 17:48:00
  
  Writing application                      : Chrome
  
  Writing application                      : Chrome
  
  Writing library                          : Chrome
  
  Writing library                          : Chrome
  
  IsTruncated                              : Yes
  
  
  
  Video
  
  Count                                    : 332
  
  Count of stream of this kind             : 1
  
  Kind of stream                           : Video
  
  Kind of stream                           : Video
  
  Stream identifier                        : 0
  
  StreamOrder                              : 1
  
  ID                                       : 2
  
  ID                                       : 2
  
  Unique ID                                : 62101435245162993
  
  Format                                   : VP9
  
  Commercial name                          : VP9
  
  Codec ID                                 : V_VP9
  
  Codec ID/Url                             : http://www.webmproject.org/
  
  Codec                                    : V_VP9
  
  Codec                                    : V_VP9
  
  Width                                    : 640
  
  Width                                    : 640 pixels
  
  Height                                   : 480
  
  Height                                   : 480 pixels
  
  Pixel aspect ratio                       : 1.000
  
  Display aspect ratio                     : 1.333
  
  Display aspect ratio                     : 4:3
  
  Frame rate mode                          : VFR
  
  Frame rate mode                          : Variable
  
  Language                                 : en
  
  Language                                 : English
  
  Language                                 : English
  
  Language                                 : en
  
  Language                                 : eng
  
  Language                                 : en
  
  Default                                  : Yes
  
  Default                                  : Yes
  
  Forced                                   : No
  
  Forced                                   : No
  
  
  
  Audio
  
  Count                                    : 272
  
  Count of stream of this kind             : 1
  
  Kind of stream                           : Audio
  
  Kind of stream                           : Audio
  
  Stream identifier                        : 0
  
  StreamOrder                              : 0
  
  ID                                       : 1
  
  ID                                       : 1
  
  Unique ID                                : 32224324715799545
  
  Format                                   : Opus
  
  Format/Url                               : http://opus-codec.org/
  
  Commercial name                          : Opus
  
  Internet media type                      : audio/opus
  
  Codec ID                                 : A_OPUS
  
  Codec ID/Url                             : http://opus-codec.org
  
  Codec                                    : Opus
  
  Codec                                    : Opus
  
  Codec/Family                             : PCM
  
  Channel(s)                               : 1
  
  Channel(s)                               : 1 channel
  
  Channel positions                        : Front: C
  
  Channel positions                        : 1/0/0
  
  Sampling rate                            : 48000
  
  Sampling rate                            : 48.0 KHz
  
  Compression mode                         : Lossy
  
  Compression mode                         : Lossy
  
  Delay                                    : 718
  
  Delay                                    : 718ms
  
  Delay                                    : 718ms
  
  Delay                                    : 718ms
  
  Delay                                    : 00:00:00.718
  
  Delay, origin                            : Container
  
  Delay, origin                            : Container
  
  Language                                 : en
  
  Language                                 : English
  
  Language                                 : English
  
  Language                                 : en
  
  Language                                 : eng
  
  Language                                 : en
  
  Default                                  : Yes
  
  Default                                  : Yes
  
  Forced                                   : No
  
  Forced                                   : No

  What did I do wrong ? Do I have to re-encode it after the chunks get appended ? Is there some attribute I’m missing ? VP9 is supposed to reduce file sizes drastically.

• Seam carving

  13 février 2008, par Mikko Koppanen — Imagick, PHP stuff

  Today I was reading trough the ImageMagick ChangeLog and noticed an interesting entry. “Add support for liquid rescaling”. I rushed to check the MagickWand API docs and there it was : MagickLiquidRescaleImage ! After about ten minutes of hacking the Imagick support was done. Needless to say ; I was excited

  For those who don’t know what seam carving is check the demo here. More detailed information about the algorithm can be found here : “Seam Carving for Content-Aware Image Resizing” by Shai Avidan and Ariel Shamir

  To use this functionality you need to install at least ImageMagick 6.3.8-2 and liblqr. Remember to pass –with-lqr to ImageMagick configuration line. You can get liblqr here : http://liblqr.wikidot.com/. The Imagick side of the functionality should appear in the CVS today if everything goes as planned.

  Here is a really simple example just to illustrate the results of the operation. The parameters might be far from optimal (didn’t do much testing yet). The original dimensions of image are 500×375 and the resulting size is 500×200.

  Update : the functionality is pending until license issues are solved.

  php

  < view plain text >

  1. < ?php
  2.  
  3. /* Create new object */
  4. $im = new Imagick( ’test.jpg’ ) ;
  5.  
  6. /* Scale down */
  7. $im->liquidRescaleImage( 500, 200, 3, 25 ) ;
  8.  
  9. /* Display */
  10. header( ’Content-Type : image/jpg’ ) ;
  11. echo $im ;
  12.  
  13.  ?>

  The original image by flickr/jennconspiracy

  

  And the result :

  

  Update. On kenrick’s request here is an image which is scaled down to 300×300

  

• Your 6-step guide to increasing acquisition

  2 juillet 2019, par Matomo Core Team — Analytics Tips
  Your 6-step guide to increasing acquisition

  Want to save time and money, as well as increase conversions and acquisition ? Matomo Analytics is here to help with that !

  Let’s start by helping you create a website visitors’ acquisition strategy, without it you might be going in blind and missing opportunities that might’ve been easily found in your metrics.

  To help you craft a strategy for your site, check out the steps below !

  Step one : Get familiar with the Acquisition feature

  The easiest way is to start with Matomo’s Acquisition feature itself. Discover and take action on the marketing channels with the biggest ROI for your business. You’ll learn :

  How to get traffic from external websites : Find out who’s helping you succeed from external websites and convince them to do more of it. Get more traffic by proactively asking for : paid sponsorships ; guest blog posts ; or spending more advertising on the particular website.

  

  About Social Networks : Which social media channels are connecting with the audience you want ? Take the guesswork out by using only the ones you need. By finding out which social channels your ideal audience prefers, you can generate shareable, convincing and engaging content to drive shares and traffic through to your site.

  Campaigns : This helps you understand which marketing campaign is working and which isn’t. You can then shift your efforts to effectively gain more visitors with less costs. Keep track of every ad and content piece you show across internal and external channels to see which has the biggest impact on your business objectives.

  Enhanced SEO : Every acquisition plan needs a focus on maximising your Search Engine Optimization (SEO) efforts. When it comes to getting conclusive search engine referrer metrics, you need to be sure you’re getting ALL the insights to drive your SEO strategy. See keyword position rankings, integrate Google, Bing and Yahoo search consoles, and no longer be restricted with “keyword not defined” showing up in your keywords reports.

  >> Watch Acquisition introduction video (playtime : 2.54 minutes)

  Step two : Set your goals and monitor conversion funnels

  Let the Goals feature guide you

  Goals are essential for building your marketing strategy and getting new customers. The more goals you track, the more you learn about behavioural changes and modify pathways to impact acquisitions over time. 

  Are you checking :

  • Which channels are converting the best for your business ?
  • Which cities/countries are most popular ?
  • What devices will attract the most visitors ?
  • How engaged your visitors are before converting ?

  This way you can see if your campaigns (SEO, PPC, signups, blogs etc.) or optimising efforts (A/B Testing, Funnels) have made an impact with the time and investment you’ve put in.

  >> Watch Goals introduction video (playtime : 2.04 minutes)

  The Funnels feature leads you to success

  Conversion funnels give you the big picture on whether your acquisition plans are paying off and where they may be falling short. If the ultimate goal of your site is to drive conversions, then each funnel can tell you how effectively you’re driving traffic through to your desired outcome.

  >> Watch Funnels introduction video (playtime : 2.29 minutes)

  

  Step three : Measure the success of every touchpoint in your customer’s journey

  Multi Attribution feature

  Accurately identify channels where visitors first engage with your business, as well as the final channel they came from, before purchasing your product/service. This helps you make smarter decisions when determining acquisition spend to accurately calculate the Customer Acquisition Cost (CAC). Here you no longer falsely over-estimate investment in failing marketing channels.

  >> Watch Multi Attribution introduction video (playtime : 2.28 minutes)

  Step four : For ecommerce sites, understand who your customers are to increase sales

  Ecommerce feature to significantly increase $ potential

  If your website’s overall purpose is to generate revenue, the Ecommerce feature gives you comprehensive insights into your customer’s purchasing behaviours.

  This heavily reduces your risks when marketing products to potential customers as you’ll understand who to target, what to target them with and where further opportunities exist.

  >> Watch Ecommerce introduction video (playtime : 2.04 minutes)

  

  Step five : Make sure the forms on your website are easy to complete

  Form Analytics feature

  Once you get visitors through the funnel, the forms on your website are the final step to conversion and need special attention. If not done right, you could be missing out on converting a large portion of your visitors.

  Thankfully, you can now identify and fix pain points on the forms that are most important to your business’ success.

  >> Watch Form Analytics introduction video (playtime : 2.39 minutes)

  

  Step six : Discover what a customer journey looks like on a user-by-user basis and bring in key acquisition elements to your strategy

  Visitor Profiles tell you each visitors’ history

  The Profile feature summarises every visit, action and purchase made.

  Better understand :

  • Why your visitors viewed your website.
  • Why your returning visitors continue to view your website.
  • What specifically your visitors are looking for and whether they found it on your website.

  The benefit is being able to see how a combination of acquisition channels play a part in a single buyer’s journey.

  >> Watch Visitors introduction video (playtime : 1.46 minutes)

  

  To summarise

  This guide will set you on a path to creating a well-planned acquisition strategy. It’s the key to attracting and capturing the attention of potential visitors/leads, and successfully driving them through a funnel/buyer’s journey on your website.

  Because of Matomo’s reputation as a trusted analytics platform, the features above can be used to assist you in making smarter data-driven decisions. You can pursue different acquisition avenues with confidence and create a strategy that’s agile and ready for success, all while respecting user privacy.