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• ffmpeg and pulse audio creating buzzy speech

  17 juin 2017, par flashape

  I’m attempting to record video and audio from an ec2 instance (Ubuntu 16.04), using xvfb and pulse audio. Everything works fine, except that the output file contains "buzzy" speech (not sure if this is what "clipping" is ?). This happens using either aac or mp3 audio codecs.

  Sample audio file : http://s000.tinyupload.com/index.php?file_id=86237391396073526211

  ffmpeg command :

  ffmpeg \
  
  -f x11grab -framerate 30 -video_size ${SCREEN_WIDTH}x${SCREEN_HEIGHT} -i :1.0 \
  
  -f pulse -i default \
  
  -c:v libx264 -preset veryfast -maxrate 2500k -bufsize 2500k -vf "format=yuv420p" -g 60 \
  
  -c:a aac -strict -2 -channel_layout stereo  -ab 256k -ar 48000 -bufsize 512k -ac 2  \
  
  -flags +global_header -f flv "test.mp4"

  The output from ffmpeg when I run the command :

  Input #0, x11grab, from ':1.0':
  
    Duration: N/A, start: 1497567394.762052, bitrate: N/A
  
      Stream #0:0: Video: rawvideo (BGR[0] / 0x524742), bgr0, 1360x764, 30 fps, 30 tbr, 1000k tbn, 30 tbc
  
  Guessed Channel Layout for  Input Stream #1.0 : stereo
  
  Input #1, pulse, from 'default':
  
    Duration: N/A, start: 1497567396.743667, bitrate: 1536 kb/s
  
      Stream #1:0: Audio: pcm_s16le, 48000 Hz, 2 channels, s16, 1536 kb/s
  
  [libx264 @ 0x1977d20] using cpu capabilities: MMX2 SSE2Fast SSSE3 SSE4.2 AVX FMA3 AVX2 LZCNT BMI2
  
  [libx264 @ 0x1977d20] profile High, level 3.2
  
  [libx264 @ 0x1977d20] 264 - core 148 r2643 5c65704 - H.264/MPEG-4 AVC codec - Copyleft 2003-2015 - http://www.videolan.org/x264.html - options: cabac=1 ref=1 deblock=1:0:0 analyse=0x3:0x113 me=hex subme=2 psy=1 psy_rd=1.00:0.00 mixed_ref=0 me_range=16 chroma_me=1 trellis=0 8x8dct=1 cqm=0 deadzone=21,11 fast_pskip=1 chroma_qp_offset=0 threads=3 lookahead_threads=1 sliced_threads=0 nr=0 decimate=1 interlaced=0 bluray_compat=0 constrained_intra=0 bframes=3 b_pyramid=2 b_adapt=1 b_bias=0 direct=1 weightb=1 open_gop=0 weightp=1 keyint=60 keyint_min=6 scenecut=40 intra_refresh=0 rc_lookahead=10 rc=crf mbtree=1 crf=23.0 qcomp=0.60 qpmin=0 qpmax=69 qpstep=4 vbv_maxrate=2500 vbv_bufsize=512 crf_max=0.0 nal_hrd=none filler=0 ip_ratio=1.40 aq=1:1.00
  
  Output #0, flv, to 'test.mp4':
  
    Metadata:
  
      encoder         : Lavf56.40.101
  
      Stream #0:0: Video: h264 (libx264) ([7][0][0][0] / 0x0007), yuv420p, 1360x764, q=-1--1, max. 2500 kb/s, 30 fps, 1k tbn, 30 tbc
  
      Metadata:
  
        encoder         : Lavc56.60.100 libx264
  
      Stream #0:1: Audio: aac ([10][0][0][0] / 0x000A), 48000 Hz, stereo, fltp, 256 kb/s
  
      Metadata:
  
        encoder         : Lavc56.60.100 aac
  
  Stream mapping:
  
    Stream #0:0 -> #0:0 (rawvideo (native) -> h264 (libx264))
  
    Stream #1:0 -> #0:1 (pcm_s16le (native) -> aac (native))

  Based on various posts, I thought it might be something in the pulse config, particularly the "resample-method" setting, but that doesn’t appear to do anything. Here is how the /etc/pulse/daemon.conf config file currently stands :

  ; daemonize = no
  
  ; fail = yes
  
  ; allow-module-loading = yes
  
  ; allow-exit = yes
  
  ; use-pid-file = yes
  
  ; system-instance = no
  
  ; local-server-type = user
  
  ; enable-shm = yes
  
  ; shm-size-bytes = 0 # setting this 0 will use the system-default, usually 64 MiB
  
  ; lock-memory = no
  
  ; cpu-limit = no
  
  
  
  ; high-priority = yes
  
  ; nice-level = -11
  
  
  
  ; realtime-scheduling = yes
  
  ; realtime-priority = 5
  
  
  
  ; exit-idle-time = 20
  
  ; scache-idle-time = 20
  
  
  
  ; dl-search-path = (depends on architecture)
  
  
  
  ; load-default-script-file = yes
  
  ; default-script-file = /etc/pulse/default.pa
  
  
  
  ; log-target = auto
  
  ; log-level = notice
  
  ; log-meta = no
  
  ; log-time = no
  
  ; log-backtrace = 0
  
  
  
  ; resample-method = speex-float-1
  
  ; resample-method = speex-float-10
  
  resample-method = speex-fixed-10
  
  ; enable-remixing = yes
  
  enable-lfe-remixing = yes
  
  ; lfe-crossover-freq = 120
  
  
  
  flat-volumes = no
  
  
  
  ; rlimit-fsize = -1
  
  ; rlimit-data = -1
  
  ; rlimit-stack = -1
  
  ; rlimit-core = -1
  
  ; rlimit-as = -1
  
  ; rlimit-rss = -1
  
  ; rlimit-nproc = -1
  
  ; rlimit-nofile = 256
  
  ; rlimit-memlock = -1
  
  ; rlimit-locks = -1
  
  ; rlimit-sigpending = -1
  
  ; rlimit-msgqueue = -1
  
  ; rlimit-nice = 31
  
  ; rlimit-rtprio = 9
  
  ; rlimit-rttime = 200000
  
  
  
  ; default-sample-format = s16le
  
  default-sample-format = s32le
  
  default-sample-rate = 44100
  
  ; default-sample-rate = 48000
  
  ; alternate-sample-rate = 48000
  
  alternate-sample-rate = 44100
  
  ; default-sample-channels = 2
  
  ; default-channel-map = front-left,front-right
  
  
  
  ; default-fragments = 4
  
  ; default-fragment-size-msec = 25
  
  ; default-fragments = 4
  
  ; default-fragment-size-msec = 25
  
  
  
  
  
  ; enable-deferred-volume = yes
  
  deferred-volume-safety-margin-usec = 1
  
  ; deferred-volume-extra-delay-usec = 0

  Edit :

  Ok, updated the ffmpeg command to capture only the audio, but still have the same issue :

  ffmpeg \
  
  -f pulse -i default \
  
  -c:a aac -strict -2 -channel_layout stereo  -ab 256k -ar 48000 -bufsize 512k -ac 2  \
  
  test.aac

  I do get some interesting messages in the output about timestamps being off :

  [aac @ 0x12a4900] Queue input is backward in timeits/s
  
  [adts @ 0x12a35a0] Application provided invalid, non monotonically increasing dts to muxer in stream 0: 182857 >= 175924
  
  [adts @ 0x12a35a0] Application provided invalid, non monotonically increasing dts to muxer in stream 0: 182857 >= 176948
  
  [adts @ 0x12a35a0] Application provided invalid, non monotonically increasing dts to muxer in stream 0: 182857 >= 177972
  
  [adts @ 0x12a35a0] Application provided invalid, non monotonically increasing dts to muxer in stream 0: 182857 >= 178996
  
  [adts @ 0x12a35a0] Application provided invalid, non monotonically increasing dts to muxer in stream 0: 182857 >= 180020
  
  [adts @ 0x12a35a0] Application provided invalid, non monotonically increasing dts to muxer in stream 0: 182857 >= 181044
  
  [adts @ 0x12a35a0] Application provided invalid, non monotonically increasing dts to muxer in stream 0: 182857 >= 182068
  
  [aac @ 0x12a4900] Queue input is backward in time
  
  [adts @ 0x12a35a0] Application provided invalid, non monotonically increasing dts to muxer in stream 0: 193354 >= 183406
  
  [adts @ 0x12a35a0] Application provided invalid, non monotonically increasing dts to muxer in stream 0: 193354 >= 184430
  
  [adts @ 0x12a35a0] Application provided invalid, non monotonically increasing dts to muxer in stream 0: 193354 >= 185454
  
  [adts @ 0x12a35a0] Application provided invalid, non monotonically increasing dts to muxer in stream 0: 193354 >= 186478
  
  [adts @ 0x12a35a0] Application provided invalid, non monotonically increasing dts to muxer in stream 0: 193354 >= 187502
  
  [adts @ 0x12a35a0] Application provided invalid, non monotonically increasing dts to muxer in stream 0: 193354 >= 188526
  
  [aac @ 0x12a4900] Queue input is backward in time
  
  [adts @ 0x12a35a0] Application provided invalid, non monotonically increasing dts to muxer in stream 0: 193354 >= 189550
  
  [adts @ 0x12a35a0] Application provided invalid, non monotonically increasing dts to muxer in stream 0: 193354 >= 190574
  
  [adts @ 0x12a35a0] Application provided invalid, non monotonically increasing dts to muxer in stream 0: 193354 >= 169622
  
  [adts @ 0x12a35a0] Application provided invalid, non monotonically increasing dts to muxer in stream 0: 193354 >= 170646
  
  [adts @ 0x12a35a0] Application provided invalid, non monotonically increasing dts to muxer in stream 0: 193354 >= 171670
  
  [adts @ 0x12a35a0] Application provided invalid, non monotonically increasing dts to muxer in stream 0: 193354 >= 172694
  
  [adts @ 0x12a35a0] Application provided invalid, non monotonically increasing dts to muxer in stream 0: 193354 >= 173718
  
  [adts @ 0x12a35a0] Application provided invalid, non monotonically increasing dts to muxer in stream 0: 193354 >= 174742
  
  [aac @ 0x12a4900] Queue input is backward in time
  
  [adts @ 0x12a35a0] Application provided invalid, non monotonically increasing dts to muxer in stream 0: 193354 >= 175766
  
  [adts @ 0x12a35a0] Application provided invalid, non monotonically increasing dts to muxer in stream 0: 193354 >= 176790
  
  [adts @ 0x12a35a0] Application provided invalid, non monotonically increasing dts to muxer in stream 0: 193354 >= 157020
  
  [adts @ 0x12a35a0] Application provided invalid, non monotonically increasing dts to muxer in stream 0: 193354 >= 158083
  
  [adts @ 0x12a35a0] Application provided invalid, non monotonically increasing dts to muxer in stream 0: 193354 >= 159107
  
  [adts @ 0x12a35a0] Application provided invalid, non monotonically increasing dts to muxer in stream 0: 193354 >= 160131
  
  [adts @ 0x12a35a0] Application provided invalid, non monotonically increasing dts to muxer in stream 0: 193354 >= 161155
  
  [adts @ 0x12a35a0] Application provided invalid, non monotonically increasing dts to muxer in stream 0: 193354 >= 162179
  
  [adts @ 0x12a35a0] Application provided invalid, non monotonically increasing dts to muxer in stream 0: 193354 >= 163203
  
  [aac @ 0x12a4900] Queue input is backward in time
  
  [adts @ 0x12a35a0] Application provided invalid, non monotonically increasing dts to muxer in stream 0: 193354 >= 164227
  
  [adts @ 0x12a35a0] Application provided invalid, non monotonically increasing dts to muxer in stream 0: 193354 >= 165251
  
  [adts @ 0x12a35a0] Application provided invalid, non monotonically increasing dts to muxer in stream 0: 193354 >= 154697
  
  [adts @ 0x12a35a0] Application provided invalid, non monotonically increasing dts to muxer in stream 0: 193354 >= 159400
  
  [adts @ 0x12a35a0] Application provided invalid, non monotonically increasing dts to muxer in stream 0: 193354 >= 160424
  
  [adts @ 0x12a35a0] Application provided invalid, non monotonically increasing dts to muxer in stream 0: 193354 >= 161448
  
  [adts @ 0x12a35a0] Application provided invalid, non monotonically increasing dts to muxer in stream 0: 193354 >= 162472
  
  [adts @ 0x12a35a0] Application provided invalid, non monotonically increasing dts to muxer in stream 0: 193354 >= 163496
  
  [adts @ 0x12a35a0] Application provided invalid, non monotonically increasing dts to muxer in stream 0: 193354 >= 164520
  
  [adts @ 0x12a35a0] Application provided invalid, non monotonically increasing dts to muxer in stream 0: 193354 >= 165544
  
  [adts @ 0x12a35a0] Application provided invalid, non monotonically increasing dts to muxer in stream 0: 193354 >= 166568
  
  [adts @ 0x12a35a0] Application provided invalid, non monotonically increasing dts to muxer in stream 0: 193354 >= 171795
  
  [adts @ 0x12a35a0] Application provided invalid, non monotonically increasing dts to muxer in stream 0: 193354 >= 172819
  
  [adts @ 0x12a35a0] Application provided invalid, non monotonically increasing dts to muxer in stream 0: 193354 >= 173843
  
  [adts @ 0x12a35a0] Application provided invalid, non monotonically increasing dts to muxer in stream 0: 193354 >= 174867
  
  [adts @ 0x12a35a0] Application provided invalid, non monotonically increasing dts to muxer in stream 0: 193354 >= 175891
  
  [adts @ 0x12a35a0] Application provided invalid, non monotonically increasing dts to muxer in stream 0: 193354 >= 176915
  
  [adts @ 0x12a35a0] Application provided invalid, non monotonically increasing dts to muxer in stream 0: 193354 >= 177939
  
  [adts @ 0x12a35a0] Application provided invalid, non monotonically increasing dts to muxer in stream 0: 193354 >= 178963
  
  [adts @ 0x12a35a0] Application provided invalid, non monotonically increasing dts to muxer in stream 0: 193354 >= 187279
  
  [adts @ 0x12a35a0] Application provided invalid, non monotonically increasing dts to muxer in stream 0: 193354 >= 189829
  
  [adts @ 0x12a35a0] Application provided invalid, non monotonically increasing dts to muxer in stream 0: 193354 >= 190853
  
  [adts @ 0x12a35a0] Application provided invalid, non monotonically increasing dts to muxer in stream 0: 193354 >= 191877
  
  [adts @ 0x12a35a0] Application provided invalid, non monotonically increasing dts to muxer in stream 0: 193354 >= 192901
  
  [aac @ 0x12a4900] Queue input is backward in time
  
      Last message repeated 2 times
  
  [adts @ 0x12a35a0] Application provided invalid, non monotonically increasing dts to muxer in stream 0: 216609 >= 216172
  
  [aac @ 0x12a4900] Queue input is backward in time
  
  [adts @ 0x12a35a0] Application provided invalid, non monotonically increasing dts to muxer in stream 0: 216609 >= 214950
  
  [adts @ 0x12a35a0] Application provided invalid, non monotonically increasing dts to muxer in stream 0: 216609 >= 214933
  
  [adts @ 0x12a35a0] Application provided invalid, non monotonically increasing dts to muxer in stream 0: 216609 >= 214836

• Piwik Analytics and becoming a Piwik Certified Professional

  10 juillet 2017, par Piwik Core Team — About

  Digital Analytics software

  Piwik Analytics is the leading open source digital analytics software, offering users around the world an opportunity to liberate their analytics. Most recently, they have introduced the Piwik Certified Professional certification exam which now allows users to become qualified in Piwik Analytics software on an individual level to gain a deeper understanding of Piwik. In this blog post I will guide you through the topics that are covered during the exam and provide you with advice on taking the official Piwik Certified Professional exam.

  

  Piwik certification exam

  Taking the exam will cost you a maximum investment of 60 minutes of your time, besides learning all materials of course. The exam consists of 55 multiple choice questions with four answers to choose from. The score needed to pass is 80% (44 questions answered correctly) and the cost is 50 USD total. An earned certificate is valid for 18 months, before these eighteen months are over a person should pass the exam again in order to retain the certified status.

  Learning topics

  The exam consists of two sections. The main section is focused on the Piwik Analytics software itself while the second part relates to digital analytics in general. All topics and content covered about Piwik Analytics is available through the official Piwik user guides. The second section tests your experience as a digital analyst, online marketer or any other function title in which you work with Piwik Analytics. In this case, the general digital analytics questions should be quite straightforward and easy to answer, and cover only a fraction of the total questions in the exam (around 10% with 5-7 general questions). An outline of all exam topics are listed below :

  • A Tour of Piwik
  • Track Goals and Measure Conversions
  • Event Tracking
  • Content Tracking
  • Ecommerce Analytics
  • Row Evolution – View and compare historical data
  • Segmentation – Compare segments of visitors
  • Visitors Maps – World, region, city
  • Real Time Visitor World Map
  • Real Time Analytics
  • The Visitor Profile
  • Site speed and Page speed
  • Site Search Tracking and Reporting
    
  • Transitions – Analyze the previous and following actions of your visitors for each page
  • Page Overlay
  • Custom Variables Analytics
  • Custom Dimensions
  • User ID
  • Annotating your data
  • Tracking Campaigns
  • URL Builder for Marketing Campaign Tracking

  The best way to prepare for the exam is read the entire Piwik user guides. You should definitely read the “Analytics Features” section since most questions of the Piwik Certified Professional – Digital Analytics exam that will be asked come from these sections. Furthermore you should be able to find your way around in Piwik at a basic level which means you know what the reports mean and where to find certain information. In addition, some basic knowledge regarding the settings is useful too. The exam is definitely not a technical implementation exam so no coding knowledge or any other deeply technical knowledge regarding Piwik is required.

  Finally, some general questions will be asked regarding digital analytics covering topics about KPI’s and the role of the analyst within an organization. While Piwik provides some links to articles by Avinash Kaushik covering these topics, you will not be able to learn these topics just by reading. When you have some experience with digital analytics you should be able to answer these general digital analytics questions with common sense and (even basic) experience as a digital analyst, analytics consultant, online marketer or any other related job whereby you work with Piwik.

  Taking the exam

  With 55 questions to be answered in 60 minutes the key to passing the exam is to keep moving. You have about 1 minute and 5 seconds to answer each question. This means that you should focus on the easiest questions first and return later to the questions that are a bit more challenging to answer. Keep an eye on the timer that will be displayed in the exam window. When the time expires or you click ‘Finish test’ your exam will end and be automatically submitted for review. Remember to first check all questions and answers before you click on the ‘Finish test’ button. If you click too soon and you still haven’t answered all questions, all unanswered questions will be marked as incorrect.

  During the test, no hard copy or online materials may be referenced. As you can imagine, it is almost impossible to check if users reference these kind of materials. However, be aware of the penalty system that is in place during the test. When a user leaves from the active test screen to another screen (i.e. a different browser tab) the screen turns red and provides a warning count when the user returns to the test screen again. You will have three warnings, after this your test will be submitted and graded as false. Furthermore, keep in mind you will have to do the test in one go and cannot pause and come back another time.

  Practice makes perfect

  Below I have included some example questions that could be asked during the exam. These questions do not necessarily represent how Piwik will test you on these topics.

  • What is the default report date that is selected by Piwik ?
  • Why would someone flatten a report in Piwik ?
  • Why would a user especially use the Page Overlay report ?
  • What are the three main Ecommerce interactions tracked with Piwik ?
  • What is an example of an anonymized IP address in Piwik ?

  Passing the Piwik Certified Professional – Digital Analytics exam

  Directly after submitting the exam you will receive a notification telling you whether or not you have passed the exam. If you pass, you will be able to download your personal certification right away. A report of your exam performance will also be available. This report lists the amount of correct answers and total questions by topic. The report with your exam performance is also available if you did not pass the exam. The certificate is valid for 18 months from the date of successful completion.

  Sometimes the difference between passing and failing can be a matter of how you interpret some of Piwik’s questions. There are several tricky questions included, so be sure to pay attention to detail on every question. If you fail, you may take the exam again. You will have to pay the 50 USD fee for each try, so do your best to pass it the first time.

  → Register to become a Piwik Certified Professional.

  We wish you the best of luck and happy analytics !

• Anomalie #4003 (Fermé) : Accessibilité du sélecteur de rubrique : demande de report dans SPIP 3.0 ...

  25 septembre 2017, par - Equipement

  Bonjour,

  Il serait souhaitable de reporter dans la branche SPIP 3.0 le correctif r22364 du 29/07/2015 : mettre un href (#) et un title sur l’icône loupe du sélecteur ajax pour y avoir accès au clavier.
  En effet, un webmestre non voyant m’a signalé qu’il ne peut pas changer un article de rubrique dans SPIP 3.0 (alors qu’il pouvait le faire sous SPIP 2.1).

  Cordialement
  Equipement