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• Matomo’s new story : our stronger vision for the future

  31 octobre 2018, par Matthieu Aubry — Community

  

  Over the past year, the team here at Matomo have been working on a very exciting project we’d love to share with you.

  It’s to do with the impact we hope for Matomo to have.

  As you all know, the world changes at too fast a pace. New technologies, new phones, new everything in the blink of an eye. That’s not what will be happening here.

  Instead, we’d like to believe it’s a refresh. Taking stock of how far we’ve come, what we’ve achieved so far, and how far we still have to go.

  So we’re rebranding.

  The rebrand

  Like a caterpillar emerging from a cocoon, we hope to be a reborn analytics butterfly.

  As a result of some careful planning and reflection we’ll be updating our logo, website and reasserting our voice.

  It’s our chance to look at ourselves in a new light. We are a mighty analytics platform and it should be known we’re comparable to the likes of Google Analytics 360.

  Along with the refresh of imagery, we listened to your feedback about the confusion between our two identities, so we’re also taking this opportunity to unite both the business brand of Innocraft with the community brand Matomo into one website.

  It makes it easier for people from all walks of life, either as individuals or in large companies, to see us as being able to get down to business with a powerful analytics tool, as well as think on behalf of our community.

  We’re the same, but with slight changes in our appearance and a stronger vision for the future.

  How far we’ve come …

  When we started out, it was about building a community around a movement. From the beginning we were concerned about data ownership, privacy and all things that came with that.

  With the help of our community and contributors, we turned Matomo (formerly Piwik) into the trusted #1 open source analytics tool it is today. We’re committed to our community. But we also need to do more.

  We’ve been niche and happy staying small, but now we need to take action and start shouting far and wide about what we do.

  We once said we need : “To create, as a community, the leading international open source digital analytics platform, that gives every user full control of their data.”

  We believe we’ve done that, so we’ll take it one step further.

  A web analytics revolution has begun …

  Begun ?

  The line signifies a new beginning.

  This is us standing up and reasserting our voice.

  Our new chapter.

  The rebrand is our chance to show that, yes, the world is changing, but when it comes to privacy, there are matters meant to be sacred. Privacy is a human right.

  What makes it worse in this ever-changing landscape, with data breaches and stolen information, is that losing control of our data is scary, we have a right to know what’s going on with our information and this must start with us.

  We know we need to champion this cause for privacy and data ownership.

  We came together as a community and built something powerful, a free open-source analytics platform, that kept the integrity of the people using it.

  It’s important for us now to feel more empowered to believe in our right to privacy, information and our ability to act independently of large corporations.

  The time is here for us to speak up and take back control.

  Once more, we need to come together to build something even more powerful, a safer online society.

  Join us.

  Sincerely,
  Matthieu Aubry on behalf of the Matomo team

• "Non-monotonous DTS in output stream 0:0 This may result in incorrect timestamps in the output file." error

  1er août 2019, par petaire

  I’m trying to go from .mkv to .mp4 through ffmpeg. Normally I would use

  ffmpeg -i $1 -codec copy -strict -2 $2

  But on this particular file, I get this error, like, A LOT :

  Non-monotonous DTS in output stream 0:0; previous: 49189232, current: 49189232; changing to 49189233. This may result in incorrect timestamps in the output file.

  I guess it has something to do with the DTS :

  [mp4 @ 0x7f8b14001200] Invalid DTS: 14832 PTS: 13552 in output stream 0:0, replacing by guess
  
  [mp4 @ 0x7f8b14001200] Invalid DTS: 15472 PTS: 12272 in output stream 0:0, replacing by guess

  I would not care if the result was ok, but the sound is out of sync, and the video is "stuttering". Feels like everything is out of sync.

  I’ve tried a lot of things, including -async 1 -vsync 1 , but nothing seems to work.

  Here’s some mediainfo :

  Complete name                            : /Users/petaire/Desktop/CNEWS-2019-07-23_16-00-00h.mkv
  
  Format                                   : Matroska
  
  Format version                           : Version 2
  
  File size                                : 1.19 GiB
  
  Movie name                               : Time-2019-07-23_16:00
  
  Writing application                      : Tvheadend 4.3-1801~g7f952c2ed
  
  Writing library                          : Tvheadend Matroska muxer
  
  Original source form                     : TV
  
  Comment                                  : Time recording
  
  IsTruncated                              : Yes
  
  DATE_BROADCASTED                         : 2019-07-23 16:00:00
  
  
  
  Video
  
  ID                                       : 1
  
  Format                                   : AVC
  
  Format/Info                              : Advanced Video Codec
  
  Format profile                           : High@L4
  
  Format settings                          : CABAC / 4 Ref Frames
  
  Format settings, CABAC                   : Yes
  
  Format settings, ReFrames                : 4 frames
  
  Codec ID                                 : V_MPEG4/ISO/AVC
  
  Width                                    : 1 920 pixels
  
  Height                                   : 1 080 pixels
  
  Display aspect ratio                     : 16:9
  
  Frame rate mode                          : Constant
  
  Frame rate                               : 25.000 fps
  
  Standard                                 : Component
  
  Color space                              : YUV
  
  Chroma subsampling                       : 4:2:0
  
  Bit depth                                : 8 bits
  
  Scan type                                : MBAFF
  
  Scan type, store method                  : Interleaved fields
  
  Scan order                               : Top Field First
  
  Language                                 : English
  
  Default                                  : Yes
  
  Forced                                   : No
  
  Color range                              : Limited
  
  Color primaries                          : BT.709
  
  Transfer characteristics                 : BT.709
  
  Matrix coefficients                      : BT.709
  
  
  
  Audio
  
  ID                                       : 2
  
  Format                                   : E-AC-3
  
  Format/Info                              : Enhanced AC-3
  
  Commercial name                          : Dolby Digital Plus
  
  Codec ID                                 : A_EAC3
  
  Bit rate mode                            : Constant
  
  Bit rate                                 : 128 Kbps
  
  Channel(s)                               : 2 channels
  
  Channel layout                           : L R
  
  Sampling rate                            : 48.0 KHz
  
  Frame rate                               : 31.250 fps (1536 SPF)
  
  Compression mode                         : Lossy
  
  Delay relative to video                  : -757ms
  
  Language                                 : French
  
  Service kind                             : Complete Main
  
  Default                                  : Yes
  
  Forced                                   : No
  
  
  
  Text
  
  ID                                       : 3
  
  Format                                   : DVB Subtitle
  
  Codec ID                                 : S_DVBSUB
  
  Codec ID/Info                            : Picture based subtitle format used on DVBs
  
  Language                                 : French
  
  Default                                  : Yes
  
  Forced                                   : No

  Any idea ?

• Grand Unified Theory of Compact Disc

  1er février 2013, par Multimedia Mike — General

  This is something I started writing about a decade ago (and I almost certainly have some of it wrong), back when compact discs still had a fair amount of relevance. Back around 2002, after a few years investigating multimedia technology, I took an interest in compact discs of all sorts. Even though there may seem to be a wide range of CD types, I generally found that they’re all fundamentally the same. I thought I would finally publishing something, incomplete though it may be.

  Physical Perspective
  There are a lot of ways to look at a compact disc. First, there’s the physical format, where a laser detects where pits/grooves have disturbed the smooth surface (a.k.a. lands). A lot of technical descriptions claim that these lands and pits on a CD correspond to ones and zeros. That’s not actually true, but you have to decide what level of abstraction you care about, and that abstraction is good enough if you only care about the discs from a software perspective.

  Grand Unified Theory (Software Perspective)
  Looking at a disc from a software perspective, I have generally found it useful to view a CD as a combination of a 2 main components :

  • table of contents (TOC)
  • a long string of sectors, each of which is 2352 bytes long

  I like to believe that’s pretty much all there is to it. All of the information on a CD is stored as a string of sectors that might be chopped up into a series of anywhere from 1-99 individual tracks. The exact sector locations where these individual tracks begin are defined in the TOC.

  Audio CDs (CD-DA / Red Book)
  The initial purpose for the compact disc was to store digital audio. The strange sector size of 2352 bytes is an artifact of this original charter. “CD quality audio”, as any multimedia nerd knows, is formally defined as stereo PCM samples that are each 16 bits wide and played at a frequency of 44100 Hz.
  

  (44100 audio frames / 1 second) * (2 samples / audio frame) * 
    (16 bits / 1 sample) * (1 byte / 8 bits) = 176,400 bytes / second
  (176,400 bytes / 1 second) / (2352 bytes / 1 sector) = 75
  

  75 is the number of sectors required to store a single second of CD-quality audio. A single sector stores 1/75th of a second, or a ‘frame’ of audio (though I think ‘frame’ gets tossed around at all levels when describing CD formats).

  The term “red book” is thrown around in relation to audio CDs. There is a series of rainbow books that define various optical disc standards and the red book describes audio CDs.

  Basic Data CD-ROMs (Mode 1 / Yellow Book)
  Somewhere along the line, someone decided that general digital information could be stored on these discs. Hence, the CD-ROM was born. The standard model above still applies– TOC and string of 2352-byte sectors. However, it’s generally only useful to have a single track on a CD-ROM. Thus, the TOC only lists a single track. That single track can easily span the entire disc (something that would be unusual for a typical audio CD).

  While the model is mostly the same, the most notable difference between and audio CD and a plain CD-ROM is that, while each sector is 2352 bytes long, only 2048 bytes are used to store actual data payload. The remaining bytes are used for synchronization and additional error detection/correction.

  At least, the foregoing is true for mode 1 / form 1 CD-ROMs (which are the most common). “Mode 1″ CD-ROMs are defined by a publication called the yellow book. There is also mode 1 / form 2. This forgoes the additional error detection and correction afforded by form 1 and dedicates 2336 of the 2352 sector bytes to the data payload.

  CD-ROM XA (Mode 2 / Green Book)
  From a software perspective, these are similar to mode 1 CD-ROMs. There are also 2 forms here. The first form gives a 2048-byte data payload while the second form yields a 2324-byte data payload.

  Video CD (VCD / White Book)
  These are CD-ROM XA discs that carry MPEG-1 video and audio data.

  Photo CD (Beige Book)
  This is something I have never personally dealt with. But it’s supposed to conform to the CD-ROM XA standard and probably fits into my model. It seems to date back to early in the CD-ROM era when CDs were particularly cost prohibitive.

  Multisession CDs (Blue Book)
  Okay, I admit that this confuses me a bit. Multisession discs allow a user to burn multiple sessions to a single recordable disc. I.e., burn a lump of data, then burn another lump at a later time, and the final result will look like all the lumps were recorded as the same big lump. I remember this being incredibly useful and cost effective back when recordable CDs cost around US$10 each (vs. being able to buy a spindle of 100 CD-Rs for US$10 or less now). Studying the cdrom.h file for the Linux OS, I found a system call named CDROMMULTISESSION that returns the sector address of the start of the last session. If I were to hypothesize about how to make this fit into my model, I might guess that the TOC has some hint that the disc was recorded in multisession (which needs to be decided up front) and the CDROMMULTISESSION call is made to find the last session. Or it could be that a disc read initialization operation always leads off with the CDROMMULTISESSION query in order to determine this.

  I suppose I could figure out how to create a multisession disc with modern software, or possibly dig up a multisession disc from 15+ years ago, and then figure out how it should be read.

  CD-i
  This type puzzles my as well. I do have some CD-i discs and I thought that I could read them just fine (the last time I looked, which was many years ago). But my research for this blog post has me thinking that I might not have been seeing the entire picture when I first studied my CD-i samples. I was able to see some of the data, but sources indicate that only proper CD-i hardware is able to see all of the data on the disc (apparently, the TOC doesn’t show all of the sectors on disc).

  Hybrid CDs (Data + Audio)
  At some point, it became a notable selling point for an audio CD to have a data track with bonus features. Even more common (particularly in the early era of CD-ROMs) were computer and console games that used the first track of a disc for all the game code and assets and the remaining tracks for beautifully rendered game audio that could also be enjoyed outside the game. Same model : TOC points to the various tracks and also makes notes about which ones are data and which are audio.

  There seems to be 2 distinct things described above. One type is the mixed mode CD which generally has the data in the first track and the audio in tracks 2..n. Then there is the enhanced CD, which apparently used multisession recording and put the data at the end. I think that the reasoning for this is that most audio CD player hardware would only read tracks from the first session and would have no way to see the data track. This was a positive thing. By contrast, when placing a mixed-mode CD into an audio player, the data track would be rendered as nonsense noise.

  Subchannels
  There’s at least one small detail that my model ignores : subchannels. CDs can encode bits of data in subchannels in sectors. This is used for things like CD-Text and CD-G. I may need to revisit this.

  In Summary
  There’s still a lot of ground to cover, like how those sectors might be formatted to show something useful (e.g., filesystems), and how the model applies to other types of optical discs. Sounds like something for another post.