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• Our latest improvement to QA : Screenshot Testing

  2 octobre 2013, par benaka — Development

  Introduction to QA in Piwik

  Like any piece of good software, Piwik comes with a comprehensive QA suite that includes unit and integration tests. The unit tests make sure core components of Piwik work properly. The integration tests make sure Piwik’s tracking and report aggregation and APIs work properly.

  To complete our QA suite, we’ve recently added a new type of tests : Screenshot tests, that we use to make sure Piwik’s controller and JavaScript code works properly.

  This blog post will explain how they work and describe our experiences setting them up ; we hope to show you an example of innovative QA practices in an active open source project.

  Screenshot Tests

  As the name implies, our screenshot tests (1) first capture a screenshot of a URL, then (2) compare the result with an expected image. This lets us test the code in Piwik’s controllers and Piwik’s JavaScript simply by specifying a URL.

  Contrast this with conventional UI tests that test for page content changes. Such tests require writing large amounts of test code that, at most, check for changes in HTML. Our tests, on the otherhand, will be able to show regressions in CSS and JavaScript rendering logic with a bare minimum of testing code.

  Capturing Screenshots

  Screenshots are captured using a 3rd party tool. We tried several tools before settling on PhantomJS. PhantomJS executes a JavaScript file with an environment that allows it to create WebKit powered web views. When capturing a screenshot, we supply PhantomJS with a script that :

  • opens a web page view,
  • loads a URL,
  • waits for all AJAX requests to be completed,
  • waits for all images to be loaded
  • waits for all JavaScript to be run.

  Then it renders the completed page to an PNG file.

  • To see how we use PhantomJS see capture.js.
  • To see how we wait for AJAX requests to complete and images to load see override.js.

  Comparing Screenshots

  Once a screenshot is generated we test for UI regressions by comparing it with an expected image. There is no sort of fuzzy matching involved. We just check that the images consist of the same bytes.

  If a screenshot test fails we use ImageMagick’s compare command line tool to generate an image diff :

  

  In this example above, there was a change that caused the Search box to be hidden in the datatable. This resulted in the whole Data table report being shifted up a few pixels. The differences are visible in red color which gives rapid feedback to the developers what has changed in the last commit.

  Screenshot Tests on Travis

  We experienced trouble generating identical screenshots on different machines, so our tests were not initially automated by Travis. Once we surpassed this hurdle, we created a new github repo to store our UI tests and screenshots and then enabled the travis build for it. We also made sure that every time a commit is pushed to the Piwik repo, our travis build will push a commit to the UI test repo to run the UI tests.

  We decided to create a new repository so the main repository wouldn’t be burdened with the large screenshot files (which git would not handle very well). We also made sure the travis build would upload all the generated screenshots to a server so debugging failures would be easier.

  Problems we experienced

  Getting generated screenshots to render identically on separate machines was quite a challenge. It took months to figure out how to get it right. Here’s what we learned :

  Fonts will render identically on different machines, but different machines can pick the wrong fonts. When we first tried getting these tests to run on Travis, we noticed small differences in the way fonts were rendered on different machines. We thought this was an insurmountable problem that would occur due to the libraries installed on these machines. It turns out, the machines were just picking the wrong fonts. After installing certain fonts during our Travis build, everything started working.

  Different versions of GD can generate slightly different images. GD is used in Piwik to, among other things, generate sparkline images. Different versions of GD will result in slightly different images. They look the same to the naked eye, but some pixels will have slightly different colors. This is, unfortunately, a problem we couldn’t solve. We couldn’t make sure that everyone who runs the tests uses the same version of GD, so instead we disabled sparklines for UI testing.

  What we learned about existing screenshot capturing tools

  We tried several screenshot capturing tools before finding one that would work adequately. Here’s what we learned about them :

  • CutyCapt This is the first screenshot capturing tool we tried. CutyCapt is a C++ program that uses QtWebKit to load and take a screenshot of a page. It can’t be used to capture multiple screenshots in one run and it can’t be used to wait for all AJAX/Images/JavaScript to complete/load (at least not currently).

  • PhantomJS This is the solution we eventually chose. PhantomJS is a headless scriptable browser that currently uses WebKit as its rendering engine.

    For the most part, PhantomJS is the best solution we found. It reliably renders screenshots, allows JavaScript to be injected into pages it loads, and since it essentially just runs JavaScript code that you provide, it can be made to do whatever you want.

  • SlimerJS SlimerJS is a clone of PhantomJS that uses Gecko as the rendering engine. It is meant to function similarly to PhantomJS. Unfortunately, due to some limitations hard-coded in Mozilla’s software, we couldn’t use it.

    For one, SlimerJS is not headless. There is, apparently, no way to do that when embedding Mozilla. You can, however, run it through xvfb, however the fact that it has to create a window means some odd things can happen. When using SlimerJS, we would sometimes end up with images where tooltips would display as if the mouse was hovering over an element. This inconsistency meant we couldn’t use it for our tests.

  One tool we didn’t try was Selenium Webdriver. Although Selenium is traditionally used to create tests that check for HTML content, it can be used to generate screenshots. (Note : PhantomJS supports using a remote WebDriver.)

  Our Future Plans for Screenshot Testing

  At the moment we render a couple dozen screenshots. We test how our PHP code, JavaScript code and CSS makes Piwik’s UI look, but we don’t test how it behaves. This is our next step.

  We want to create Screenshot Unit Tests for each UI control Piwik uses (for example, the Data Table View or the Site Selector). These tests would use the Widgetize plugin to load a control by itself, then execute JavaScript that simulates events and user behavior, and finally take a screenshot. This way we can test how our code handles clicks and hovers and all sorts of other behavior.

  Screenshots Tests will make Piwik more stable and keep us agile and able to release early and often. Thank you for your support & Spreading the word about Piwik !

• Displaying 25 inputs into a 5x5 grid using -ffmpeg- with the correct layout code

  1er septembre 2021, par Clive Nicholas

  I'm now looking to expand the 4x4 code very helpfully provided by @llogan yesterday into one taking 25 different and equally-scaled audio and video inputs to make a 5x5 grid (at which point, I'll stop) :

  


  ffmpeg -i a.mp4 -i b.mp4 -i c.mp4 -i d.mp4 -i e.mp4 -i f.mp4 -i g.mp4 -i h.mp4 -i i.mp4 -i j.mp4 -i k.mp4 -i l.mp4 -i m.mp4 -i n.mp4 -i o.mp4 -i p.mp4 -i q.mp4 -i r.mp4 -i s.mp4 -i t.mp4 -i u.mp4 -i v.mp4 -i w.mp4 -i x.mp4 -i y.mp4 \
 -filter_complex \
    "[0:v]scale=iw/5:-1[v0];[1:v]scale=iw/5:-1[v1];[2:v]scale=iw/5:-1[v2]; \ 
     [3:v]scale=iw/5:-1[v3];[4:v]scale=iw/5:-1[v4];[5:v]scale=iw/5:-1[v5]; \ 
     [6:v]scale=iw/5:-1[v6];[7:v]scale=iw/5:-1[v7];[8:v]scale=iw/5:-1[v8]; \ 
     [9:v]scale=iw/5:-1[v9];[10:v]scale=iw/5:-1[v10];[11:v]scale=iw/5:-1[v11]; \
     [12:v]scale=iw/5:-1[v12];[13:v]scale=iw/5:-1[v13];[14:v]scale=iw/5:-1[v14]; \
     [15:v]scale=iw/5:-1[v15];[16:v]scale=iw/5:-1[v16];[17:v]scale=iw/5:-1[v17]; \ 
     [18:v]scale=iw/5:-1[v18];[19:v]scale=iw/5:-1[v19];[20:v]scale=iw/5:-1[v20]; \
     [21:v]scale=iw/5:-1[v21];[22:v]scale=iw/5:-1[v22];[23:v]scale=iw/5:-1[v23]; \ 
     [24:v]scale=iw/5:-1[v24]; \
     [v0][v1][v2][v3][v4][v5][v6][v7][v8][v9][v10][v11][v12][v13][v14][v15][v16][v17][v18][v19][v20][v21][v22][v23][v24]xstack=inputs=25:layout=0_0|0_h0|0_h0+h1|0_h0+h1+h2|0_h0+h1+h2+h3|w0_0|w0_h0|w0_h0+h1|w0_h0+h1+h2|w0_h0+h1+h2+h3|w0+w4_0|w0+w4_h0|w0+w4_h0+h1|w0+w4_h0+h1+h2|w0+w4_h0+h1+h2+h3|w0+w4+w8_0|w0+w4+w8_h0|w0+w4+w8_h0+h1|w0+w4+w8_h0+h1+h2|w0+w4+w8_h0+h1+h2+h3|w0+w4+w8+w12_0|w0+w4+w8+w12_h0|w0+w4+w8+w12_h0+h1|w0+w4+w8+w12_h0+h1+h2|w0+w4+w8+w12_h0+h1+h2+h3; \
     [0:a][1:a][2:a][3:a][4:a][5:a][6:a][7:a][8:a][9:a][10:a][11:a][12:a][13:a][14:a][15:a][16:a][17:a][18:a][19:a][20:a][21:a][22:a][23:a][24:a]amix=inputs=25" \
output.mp4


  


  Unfortunately, this produces errors :

  


  ffmpeg version 4.3.2-0+deb11u1ubuntu1 Copyright (c) 2000-2021 the FFmpeg developers
  built with gcc 10 (Ubuntu 10.2.1-20ubuntu1)
  configuration: --prefix=/usr --extra-version=0+deb11u1ubuntu1 --toolchain=hardened --libdir=/usr/lib/x86_64-linux-gnu --incdir=/usr/include/x86_64-linux-gnu --arch=amd64 --enable-gpl --disable-stripping --enable-avresample --disable-filter=resample --enable-gnutls --enable-ladspa --enable-libaom --enable-libass --enable-libbluray --enable-libbs2b --enable-libcaca --enable-libcdio --enable-libcodec2 --enable-libdav1d --enable-libflite --enable-libfontconfig --enable-libfreetype --enable-libfribidi --enable-libgme --enable-libgsm --enable-libjack --enable-libmp3lame --enable-libmysofa --enable-libopenjpeg --enable-libopenmpt --enable-libopus --enable-libpulse --enable-librabbitmq --enable-librsvg --enable-librubberband --enable-libshine --enable-libsnappy --enable-libsoxr --enable-libspeex --enable-libsrt --enable-libssh --enable-libtheora --enable-libtwolame --enable-libvidstab --enable-libvorbis --enable-libvpx --enable-libwavpack --enable-libwebp --enable-libx265 --enable-libxml2 --enable-libxvid --enable-libzmq --enable-libzvbi --enable-lv2 --enable-omx --enable-openal --enable-opencl --enable-opengl --enable-sdl2 --enable-pocketsphinx --enable-libmfx --enable-libdc1394 --enable-libdrm --enable-libiec61883 --enable-nvenc --enable-chromaprint --enable-frei0r --enable-libx264 --enable-shared
  WARNING: library configuration mismatch
  avcodec     configuration: --prefix=/usr --extra-version=0+deb11u1ubuntu1 --toolchain=hardened --libdir=/usr/lib/x86_64-linux-gnu --incdir=/usr/include/x86_64-linux-gnu --arch=amd64 --enable-gpl --disable-stripping --enable-avresample --disable-filter=resample --enable-gnutls --enable-ladspa --enable-libaom --enable-libass --enable-libbluray --enable-libbs2b --enable-libcaca --enable-libcdio --enable-libcodec2 --enable-libdav1d --enable-libflite --enable-libfontconfig --enable-libfreetype --enable-libfribidi --enable-libgme --enable-libgsm --enable-libjack --enable-libmp3lame --enable-libmysofa --enable-libopenjpeg --enable-libopenmpt --enable-libopus --enable-libpulse --enable-librabbitmq --enable-librsvg --enable-librubberband --enable-libshine --enable-libsnappy --enable-libsoxr --enable-libspeex --enable-libsrt --enable-libssh --enable-libtheora --enable-libtwolame --enable-libvidstab --enable-libvorbis --enable-libvpx --enable-libwavpack --enable-libwebp --enable-libx265 --enable-libxml2 --enable-libxvid --enable-libzmq --enable-libzvbi --enable-lv2 --enable-omx --enable-openal --enable-opencl --enable-opengl --enable-sdl2 --enable-pocketsphinx --enable-libmfx --enable-libdc1394 --enable-libdrm --enable-libiec61883 --enable-nvenc --enable-chromaprint --enable-frei0r --enable-libx264 --enable-shared --enable-version3 --disable-doc --disable-programs --enable-libaribb24 --enable-liblensfun --enable-libopencore_amrnb --enable-libopencore_amrwb --enable-libtesseract --enable-libvo_amrwbenc
  libavutil      56. 51.100 / 56. 51.100
  libavcodec     58. 91.100 / 58. 91.100
  libavformat    58. 45.100 / 58. 45.100
  libavdevice    58. 10.100 / 58. 10.100
  libavfilter     7. 85.100 /  7. 85.100
  libavresample   4.  0.  0 /  4.  0.  0
  libswscale      5.  7.100 /  5.  7.100
  libswresample   3.  7.100 /  3.  7.100
  libpostproc    55.  7.100 / 55.  7.100
Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'abc.mp4':
  Metadata:
    major_brand     : isom
    minor_version   : 512
    compatible_brands: isomiso2avc1mp41
    encoder         : Lavf58.45.100
  Duration: 00:00:08.00, start: 0.000000, bitrate: 248 kb/s
    Stream #0:0(und): Video: h264 (High) (avc1 / 0x31637661), yuv420p, 640x360, 41 kb/s, 60 fps, 60 tbr, 15360 tbn, 120 tbc (default)
    Metadata:
      handler_name    : VideoHandler
    Stream #0:1(und): Audio: aac (LC) (mp4a / 0x6134706D), 48000 Hz, stereo, fltp, 193 kb/s (default)
    Metadata:
      handler_name    : SoundHandler
Input #1, mov,mp4,m4a,3gp,3g2,mj2, from 'ang.mp4':
  Metadata:
    major_brand     : isom
    minor_version   : 512
    compatible_brands: isomiso2avc1mp41
    encoder         : Lavf58.45.100
  Duration: 00:00:10.00, start: 0.000000, bitrate: 480 kb/s
    Stream #1:0(und): Video: h264 (High) (avc1 / 0x31637661), yuv420p, 640x360, 271 kb/s, 60 fps, 60 tbr, 15360 tbn, 120 tbc (default)
    Metadata:
      handler_name    : VideoHandler
    Stream #1:1(und): Audio: aac (LC) (mp4a / 0x6134706D), 48000 Hz, stereo, fltp, 194 kb/s (default)
    Metadata:
      handler_name    : SoundHandler
Input #2, mov,mp4,m4a,3gp,3g2,mj2, from 'ard.mp4':
  Metadata:
    major_brand     : isom
    minor_version   : 512
    compatible_brands: isomiso2avc1mp41
    encoder         : Lavf58.45.100
  Duration: 00:00:09.00, start: 0.000000, bitrate: 256 kb/s
    Stream #2:0(und): Video: h264 (High) (avc1 / 0x31637661), yuv420p, 640x360, 49 kb/s, 60 fps, 60 tbr, 15360 tbn, 120 tbc (default)
    Metadata:
      handler_name    : VideoHandler
    Stream #2:1(und): Audio: aac (LC) (mp4a / 0x6134706D), 48000 Hz, stereo, fltp, 193 kb/s (default)
    Metadata:
      handler_name    : SoundHandler
Input #3, mov,mp4,m4a,3gp,3g2,mj2, from 'atv.mp4':
  Metadata:
    major_brand     : isom
    minor_version   : 512
    compatible_brands: isomiso2avc1mp41
    encoder         : Lavf58.45.100
  Duration: 00:00:17.00, start: 0.000000, bitrate: 259 kb/s
    Stream #3:0(und): Video: h264 (High) (avc1 / 0x31637661), yuv420p, 640x360, 53 kb/s, 60 fps, 60 tbr, 15360 tbn, 120 tbc (default)
    Metadata:
      handler_name    : VideoHandler
    Stream #3:1(und): Audio: aac (LC) (mp4a / 0x6134706D), 48000 Hz, stereo, fltp, 193 kb/s (default)
    Metadata:
      handler_name    : SoundHandler
Input #4, mov,mp4,m4a,3gp,3g2,mj2, from 'bor.mp4':
  Metadata:
    major_brand     : isom
    minor_version   : 512
    compatible_brands: isomiso2avc1mp41
    encoder         : Lavf58.45.100
  Duration: 00:00:09.00, start: 0.000000, bitrate: 255 kb/s
    Stream #4:0(und): Video: h264 (High) (avc1 / 0x31637661), yuv420p, 640x360, 48 kb/s, 60 fps, 60 tbr, 15360 tbn, 120 tbc (default)
    Metadata:
      handler_name    : VideoHandler
    Stream #4:1(und): Audio: aac (LC) (mp4a / 0x6134706D), 48000 Hz, stereo, fltp, 192 kb/s (default)
    Metadata:
      handler_name    : SoundHandler
Input #5, mov,mp4,m4a,3gp,3g2,mj2, from 'cen.mp4':
  Metadata:
    major_brand     : isom
    minor_version   : 512
    compatible_brands: isomiso2avc1mp41
    encoder         : Lavf58.45.100
  Duration: 00:00:07.00, start: 0.000000, bitrate: 461 kb/s
    Stream #5:0(und): Video: h264 (High) (avc1 / 0x31637661), yuv420p, 640x360, 250 kb/s, 60 fps, 60 tbr, 15360 tbn, 120 tbc (default)
    Metadata:
      handler_name    : VideoHandler
    Stream #5:1(und): Audio: aac (LC) (mp4a / 0x6134706D), 48000 Hz, stereo, fltp, 196 kb/s (default)
    Metadata:
      handler_name    : SoundHandler
Input #6, mov,mp4,m4a,3gp,3g2,mj2, from 'cha.mp4':
  Metadata:
    major_brand     : isom
    minor_version   : 512
    compatible_brands: isomiso2avc1mp41
    encoder         : Lavf58.45.100
  Duration: 00:00:05.00, start: 0.000000, bitrate: 267 kb/s
    Stream #6:0(und): Video: h264 (High) (avc1 / 0x31637661), yuv420p, 640x360, 59 kb/s, 60 fps, 60 tbr, 15360 tbn, 120 tbc (default)
    Metadata:
      handler_name    : VideoHandler
    Stream #6:1(und): Audio: aac (LC) (mp4a / 0x6134706D), 48000 Hz, stereo, fltp, 194 kb/s (default)
    Metadata:
      handler_name    : SoundHandler
Input #7, mov,mp4,m4a,3gp,3g2,mj2, from 'grad.mp4':
  Metadata:
    major_brand     : isom
    minor_version   : 512
    compatible_brands: isomiso2avc1mp41
    encoder         : Lavf58.45.100
  Duration: 00:00:05.01, start: 0.000000, bitrate: 246 kb/s
    Stream #7:0(und): Video: h264 (High) (avc1 / 0x31637661), yuv420p, 640x360, 39 kb/s, 60 fps, 60 tbr, 15360 tbn, 120 tbc (default)
    Metadata:
      handler_name    : VideoHandler
    Stream #7:1(und): Audio: aac (LC) (mp4a / 0x6134706D), 48000 Hz, stereo, fltp, 192 kb/s (default)
    Metadata:
      handler_name    : SoundHandler
Input #8, mov,mp4,m4a,3gp,3g2,mj2, from 'gram.mp4':
  Metadata:
    major_brand     : isom
    minor_version   : 512
    compatible_brands: isomiso2avc1mp41
    encoder         : Lavf58.45.100
  Duration: 00:00:09.00, start: 0.000000, bitrate: 294 kb/s
    Stream #8:0(und): Video: h264 (High) (avc1 / 0x31637661), yuv420p, 640x360, 86 kb/s, 60 fps, 60 tbr, 15360 tbn, 120 tbc (default)
    Metadata:
      handler_name    : VideoHandler
    Stream #8:1(und): Audio: aac (LC) (mp4a / 0x6134706D), 48000 Hz, stereo, fltp, 195 kb/s (default)
    Metadata:
      handler_name    : SoundHandler
Input #9, mov,mp4,m4a,3gp,3g2,mj2, from 'htv.mp4':
  Metadata:
    major_brand     : isom
    minor_version   : 512
    compatible_brands: isomiso2avc1mp41
    encoder         : Lavf58.45.100
  Duration: 00:00:12.01, start: 0.000000, bitrate: 238 kb/s
    Stream #9:0(und): Video: h264 (High) (avc1 / 0x31637661), yuv420p, 640x360, 29 kb/s, 60 fps, 60 tbr, 15360 tbn, 120 tbc (default)
    Metadata:
      handler_name    : VideoHandler
    Stream #9:1(und): Audio: aac (LC) (mp4a / 0x6134706D), 48000 Hz, stereo, fltp, 196 kb/s (default)
    Metadata:
      handler_name    : SoundHandler
Input #10, mov,mp4,m4a,3gp,3g2,mj2, from 'its1.mp4':
  Metadata:
    major_brand     : isom
    minor_version   : 512
    compatible_brands: isomiso2avc1mp41
    encoder         : Lavf58.45.100
  Duration: 00:00:07.00, start: 0.000000, bitrate: 238 kb/s
    Stream #10:0(und): Video: h264 (High) (avc1 / 0x31637661), yuv420p, 640x360, 31 kb/s, 60 fps, 60 tbr, 15360 tbn, 120 tbc (default)
    Metadata:
      handler_name    : VideoHandler
    Stream #10:1(und): Audio: aac (LC) (mp4a / 0x6134706D), 48000 Hz, stereo, fltp, 192 kb/s (default)
    Metadata:
      handler_name    : SoundHandler
Input #11, mov,mp4,m4a,3gp,3g2,mj2, from 'its2.mp4':
  Metadata:
    major_brand     : isom
    minor_version   : 512
    compatible_brands: isomiso2avc1mp41
    encoder         : Lavf58.45.100
  Duration: 00:00:08.00, start: 0.000000, bitrate: 241 kb/s
    Stream #11:0(und): Video: h264 (High) (avc1 / 0x31637661), yuv420p, 640x360, 34 kb/s, 60 fps, 60 tbr, 15360 tbn, 120 tbc (default)
    Metadata:
      handler_name    : VideoHandler
    Stream #11:1(und): Audio: aac (LC) (mp4a / 0x6134706D), 48000 Hz, stereo, fltp, 192 kb/s (default)
    Metadata:
      handler_name    : SoundHandler
Input #12, mov,mp4,m4a,3gp,3g2,mj2, from 'lwt.mp4':
  Metadata:
    major_brand     : isom
    minor_version   : 512
    compatible_brands: isomiso2avc1mp41
    encoder         : Lavf58.45.100
  Duration: 00:00:10.00, start: 0.000000, bitrate: 239 kb/s
    Stream #12:0(und): Video: h264 (High) (avc1 / 0x31637661), yuv420p, 640x360, 30 kb/s, 60 fps, 60 tbr, 15360 tbn, 120 tbc (default)
    Metadata:
      handler_name    : VideoHandler
    Stream #12:1(und): Audio: aac (LC) (mp4a / 0x6134706D), 48000 Hz, stereo, fltp, 195 kb/s (default)
    Metadata:
      handler_name    : SoundHandler
Input #13, mov,mp4,m4a,3gp,3g2,mj2, from 'sou.mp4':
  Metadata:
    major_brand     : isom
    minor_version   : 512
    compatible_brands: isomiso2avc1mp41
    encoder         : Lavf58.45.100
  Duration: 00:00:08.00, start: 0.000000, bitrate: 247 kb/s
    Stream #13:0(und): Video: h264 (High) (avc1 / 0x31637661), yuv420p, 640x360, 39 kb/s, 60 fps, 60 tbr, 15360 tbn, 120 tbc (default)
    Metadata:
      handler_name    : VideoHandler
    Stream #13:1(und): Audio: aac (LC) (mp4a / 0x6134706D), 48000 Hz, stereo, fltp, 194 kb/s (default)
    Metadata:
      handler_name    : SoundHandler
Input #14, mov,mp4,m4a,3gp,3g2,mj2, from 'stv.mp4':
  Metadata:
    major_brand     : isom
    minor_version   : 512
    compatible_brands: isomiso2avc1mp41
    encoder         : Lavf58.45.100
  Duration: 00:00:09.00, start: 0.000000, bitrate: 257 kb/s
    Stream #14:0(und): Video: h264 (High) (avc1 / 0x31637661), yuv420p, 640x360, 51 kb/s, 60 fps, 60 tbr, 15360 tbn, 120 tbc (default)
    Metadata:
      handler_name    : VideoHandler
    Stream #14:1(und): Audio: aac (LC) (mp4a / 0x6134706D), 48000 Hz, stereo, fltp, 192 kb/s (default)
    Metadata:
      handler_name    : SoundHandler
Input #15, mov,mp4,m4a,3gp,3g2,mj2, from 'tha.mp4':
  Metadata:
    major_brand     : isom
    minor_version   : 512
    compatible_brands: isomiso2avc1mp41
    encoder         : Lavf58.45.100
  Duration: 00:00:06.00, start: 0.000000, bitrate: 454 kb/s
    Stream #15:0(und): Video: h264 (High) (avc1 / 0x31637661), yuv420p, 640x360, 245 kb/s, 60 fps, 60 tbr, 15360 tbn, 120 tbc (default)
    Metadata:
      handler_name    : VideoHandler
    Stream #15:1(und): Audio: aac (LC) (mp4a / 0x6134706D), 48000 Hz, stereo, fltp, 194 kb/s (default)
    Metadata:
      handler_name    : SoundHandler
Input #16, mov,mp4,m4a,3gp,3g2,mj2, from 'tlc.mp4':
  Metadata:
    major_brand     : isom
    minor_version   : 512
    compatible_brands: isomiso2avc1mp41
    encoder         : Lavf58.45.100
  Duration: 00:00:09.00, start: 0.000000, bitrate: 275 kb/s
    Stream #16:0(und): Video: h264 (High) (avc1 / 0x31637661), yuv420p, 640x360, 67 kb/s, 60 fps, 60 tbr, 15360 tbn, 120 tbc (default)
    Metadata:
      handler_name    : VideoHandler
    Stream #16:1(und): Audio: aac (LC) (mp4a / 0x6134706D), 48000 Hz, stereo, fltp, 194 kb/s (default)
    Metadata:
      handler_name    : SoundHandler
Input #17, mov,mp4,m4a,3gp,3g2,mj2, from 'tsw.mp4':
  Metadata:
    major_brand     : isom
    minor_version   : 512
    compatible_brands: isomiso2avc1mp41
    encoder         : Lavf58.45.100
  Duration: 00:00:11.00, start: 0.000000, bitrate: 457 kb/s
    Stream #17:0(und): Video: h264 (High) (avc1 / 0x31637661), yuv420p, 640x360, 251 kb/s, 60 fps, 60 tbr, 15360 tbn, 120 tbc (default)
    Metadata:
      handler_name    : VideoHandler
    Stream #17:1(und): Audio: aac (LC) (mp4a / 0x6134706D), 48000 Hz, stereo, fltp, 192 kb/s (default)
    Metadata:
      handler_name    : SoundHandler
Input #18, mov,mp4,m4a,3gp,3g2,mj2, from 'ttt.mp4':
  Metadata:
    major_brand     : isom
    minor_version   : 512
    compatible_brands: isomiso2avc1mp41
    encoder         : Lavf58.45.100
  Duration: 00:00:10.01, start: 0.000000, bitrate: 258 kb/s
    Stream #18:0(und): Video: h264 (High) (avc1 / 0x31637661), yuv420p, 640x360, 51 kb/s, 60 fps, 60 tbr, 15360 tbn, 120 tbc (default)
    Metadata:
      handler_name    : VideoHandler
    Stream #18:1(und): Audio: aac (LC) (mp4a / 0x6134706D), 48000 Hz, stereo, fltp, 193 kb/s (default)
    Metadata:
      handler_name    : SoundHandler
Input #19, mov,mp4,m4a,3gp,3g2,mj2, from 'tvam.mp4':
  Metadata:
    major_brand     : isom
    minor_version   : 512
    compatible_brands: isomiso2avc1mp41
    encoder         : Lavf57.82.100
  Duration: 00:00:11.31, start: 0.000000, bitrate: 383 kb/s
    Stream #19:0(und): Video: h264 (High) (avc1 / 0x31637661), yuv420p, 352x288 [SAR 178:163 DAR 1958:1467], 251 kb/s, 25 fps, 25 tbr, 12800 tbn, 50 tbc (default)
    Metadata:
      handler_name    : VideoHandler
    Stream #19:1(und): Audio: aac (LC) (mp4a / 0x6134706D), 44100 Hz, stereo, fltp, 125 kb/s (default)
    Metadata:
      handler_name    : SoundHandler
Input #20, mov,mp4,m4a,3gp,3g2,mj2, from 'tvs.mp4':
  Metadata:
    major_brand     : isom
    minor_version   : 512
    compatible_brands: isomiso2avc1mp41
    encoder         : Lavf58.45.100
  Duration: 00:00:10.01, start: 0.000000, bitrate: 252 kb/s
    Stream #20:0(und): Video: h264 (High) (avc1 / 0x31637661), yuv420p, 640x360, 44 kb/s, 60 fps, 60 tbr, 15360 tbn, 120 tbc (default)
    Metadata:
      handler_name    : VideoHandler
    Stream #20:1(und): Audio: aac (LC) (mp4a / 0x6134706D), 48000 Hz, stereo, fltp, 194 kb/s (default)
    Metadata:
      handler_name    : SoundHandler
Input #21, mov,mp4,m4a,3gp,3g2,mj2, from 'tww.mp4':
  Metadata:
    major_brand     : isom
    minor_version   : 512
    compatible_brands: isomiso2avc1mp41
    encoder         : Lavf58.45.100
  Duration: 00:00:09.00, start: 0.000000, bitrate: 277 kb/s
    Stream #21:0(und): Video: h264 (High) (avc1 / 0x31637661), yuv420p, 640x360, 69 kb/s, 60 fps, 60 tbr, 15360 tbn, 120 tbc (default)
    Metadata:
      handler_name    : VideoHandler
    Stream #21:1(und): Audio: aac (LC) (mp4a / 0x6134706D), 48000 Hz, stereo, fltp, 194 kb/s (default)
    Metadata:
      handler_name    : SoundHandler
Input #22, mov,mp4,m4a,3gp,3g2,mj2, from 'utv.mp4':
  Metadata:
    major_brand     : isom
    minor_version   : 512
    compatible_brands: isomiso2avc1mp41
    encoder         : Lavf58.45.100
  Duration: 00:00:08.00, start: 0.000000, bitrate: 443 kb/s
    Stream #22:0(und): Video: h264 (High) (avc1 / 0x31637661), yuv420p, 640x360, 234 kb/s, 60 fps, 60 tbr, 15360 tbn, 120 tbc (default)
    Metadata:
      handler_name    : VideoHandler
    Stream #22:1(und): Audio: aac (LC) (mp4a / 0x6134706D), 48000 Hz, stereo, fltp, 194 kb/s (default)
    Metadata:
      handler_name    : SoundHandler
Input #23, mov,mp4,m4a,3gp,3g2,mj2, from 'wtv.mp4':
  Metadata:
    major_brand     : isom
    minor_version   : 512
    compatible_brands: isomiso2avc1mp41
    encoder         : Lavf58.45.100
  Duration: 00:00:08.00, start: 0.000000, bitrate: 431 kb/s
    Stream #23:0(und): Video: h264 (High) (avc1 / 0x31637661), yuv420p, 640x360, 224 kb/s, 60 fps, 60 tbr, 15360 tbn, 120 tbc (default)
    Metadata:
      handler_name    : VideoHandler
    Stream #23:1(und): Audio: aac (LC) (mp4a / 0x6134706D), 48000 Hz, stereo, fltp, 194 kb/s (default)
    Metadata:
      handler_name    : SoundHandler
Input #24, mov,mp4,m4a,3gp,3g2,mj2, from 'ytv.mp4':
  Metadata:
    major_brand     : isom
    minor_version   : 512
    compatible_brands: isomiso2avc1mp41
    encoder         : Lavf58.45.100
  Duration: 00:00:08.00, start: 0.000000, bitrate: 332 kb/s
    Stream #24:0(und): Video: h264 (High) (avc1 / 0x31637661), yuv420p, 640x360, 123 kb/s, 60 fps, 60 tbr, 15360 tbn, 120 tbc (default)
    Metadata:
      handler_name    : VideoHandler
    Stream #24:1(und): Audio: aac (LC) (mp4a / 0x6134706D), 48000 Hz, stereo, fltp, 195 kb/s (default)
    Metadata:
      handler_name    : SoundHandler
[AVFilterGraph @ 0x55ad3b4d4a00] No such filter: ' '
Error initializing complex filters.
Invalid argument


  


  The layout code has now become extremely complex, but I've carefully followed the 4x4 example as given in the manual here and I don't think I'm doing much wrong. Breaking down and reordering the layout code I used above looks like this :

  


  input1(0, 0)          | input6 (w0, 0)           | input11(w0+w4, 0)          | input16(w0+w4+w8, 0)          | input21(w0+w4+w8+w12, 0)
input2(0, h0)         | input7 (w0, h0)          | input12(w0+w4, h0)         | input17(w0+w4+w8, h0)         | input22(w0+w4+w8+w12, h0)
input3(0, h0+h1)      | input8 (w0, h0+h1)       | input13(w0+w4, h0+h1)      | input18(w0+w4+w8, h0+h1)      | input23(w0+w4+w8+w12, h0+h1)
input4(0, h0+h1+h2)   | input9 (w0, h0+h1+h2)    | input14(w0+w4, h0+h1+h2)   | input19(w0+w4+w8, h0+h1+h2)   | input24(w0+w4+w8+w12, h0+h1+h2)
input5(0, h0+h1+h2+h3)| input10(w0, h0+h1+h2+h3) | input15(w0+w4, h0+h1+h2+h3)| input20(w0+w4+w8, h0+h1+h2+h3)| input25(w0+w4+w8+w12, h0+h1+h2+h3)


  


  To my mind, w12 and h3 would logically be the next set of width and height parameters to add on in order to make the grid expansion from 4x4 to 5x5 work. Is that what's causing the code to choke ? If it's not this, it's not obvious to me what it might be, as I've checked the whole code as thoroughly as possible.

  


  Once again, I'll be very grateful for your assistance.

  


  Thanks very much, Clive

  


• Leading Google Analytics alternative, Matomo, parodies Christopher Nolan blockbuster ahead of the UA sunset

  4 juillet 2023, par Erin — Press Releases

  Wellington, New Zealand, 4 July 2023 : In the world of online data, Google Analytics has long reigned supreme. Its dominance has been unquestioned, leaving website owners with little choice but to rely on the tech giant for their data insights. However, a new dawn in web analytics is upon us, and Matomo, the leading alternative to Google Analytics, is seizing a unique opportunity to position itself as the go-to provider. In a bold move, Matomo has launched a parody trailer, “Googleheimer,” humorously taking a satirical swipe at Google in the style of the upcoming Oppenheimer biopic by Christopher Nolan.

  Capitalising on a time-bound decision

  With an important decision looming for marketers and web specialists who need to switch analytics providers by July 1st, Matomo has found the perfect window to capture their attention.

  The urgency of the situation, combined with the high intent to switch providers, sets the stage for Matomo to establish itself as the leading alternative analytics platform of choice.

  Matomo’s parody trailer addresses the frustrations of GA4 head-on by highlighting the issues and the uncertainties caused by the sunset of Universal Analytics in humorous satire with lines such as :

  “But we’re keeping everyone’s data, right ? Right ?? …RIGHT ?!”

  Riding on the coat tails of this summer’s anticipated blockbuster from Christopher Nolan, Matomo openly points at the downsides of GA4, and reflects many frustrated marketers pain points in an entertaining way. Beneath the comedic and satirical tone lies the message that users have choices, and no longer need to surrender to the behemoth incumbent.

  Matomo was founded to challenge the status quo and provide a solution for those who believe in privacy and in ethical analytics, and who prefer that their customer data not be concentrated in the hands of just a few corporations.

  Watch the full trailer here. 


  About Matomo
  

  Matomo is a world-leading open-source privacy-friendly ethical web analytics platform, trusted by over 1.4 million websites in 190 countries and translated into over 50 languages. Matomo helps businesses and organisations track and optimise their online presence allowing users to easily collect, analyse, and act on their website and marketing data to gain a deeper understanding of their visitors and drive conversions and revenue. Matomo’s vision is to create, as a community, the leading open digital analytics platform that gives every user complete control of their data.

  Visit matomo.org for more information.




  More on Google Analytics changes



  A new dawn in web analytics is upon us, and Matomo – the leading alternative to Google Analytics – is here for it. After 20 years, Google is blowing up Universal Analytics (or GA3) – and taking your data with it. Inspired by Christopher Nolan’s upcoming biopic about physicist J. Robert Oppenheimer and the making of his atomic bomb (also known as “The Manhattan Project”), this parody trailer openly points to Google and draws the comparison in humorous satire. GA4 comes with a new set of metrics, setups and reports that change how you analyse your data.