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• Re-Stream a MPEG2 TS PAL Stream with crtmpserver

  2 octobre 2011, par mblaettermann

  I want to build up some kind of stream wrapper :

  I own an old Dreambox PAL Sat Reciever with Networking. This stream I want to transcode to a lower resultion an restream it.

  My Goal is, to have a simple website, where this stream is embedded via rtmp.

  I thougt crtmpserver should be the right software. For now I have a site running and can play local files through jwplayer/crtmpserver.

  I am looking for a solution for this :

  httpUrl -> ffmpeg -> crtmpserver

  Is that possible ? May I redirect the output of ffmpeg to a filed pipe, and crtmpserver could grab that ? Or go with UDP ?

  Any hints appreciated !!! Thanks !!

• Programming Language Levels

  20 mai 2011, par Multimedia Mike — Programming

  I’ve been doing this programming thing for some 20 years now. Things sure do change. One change I ponder from time to time is the matter of programming language levels. Allow me to explain.

  The 1990s
  When I first took computer classes in the early 1990s, my texts would classify computer languages into 3 categories, or levels. The lower the level, the closer to the hardware ; the higher the level, the more abstract (and presumably, easier to use). I recall that the levels went something like this :

  • High level : Pascal, BASIC, Logo, Fortran
  • Medium level : C, Forth
  • Low level : Assembly language

  Keep in mind that these were the same texts which took the time to explain the history of computers from mainframes -> minicomputers -> a relatively recent phenomenon called microcomputers or "PCs".

  Somewhere in the mid-late 1990s, when I was at university, I was introduced to a new tier :

  • Very high level : Perl, shell scripting

  I think there was some debate among my peers about whether C++ and Java were properly classified as high or very high level. The distinction between high and very high, in my observation, seemed to be that very high level languages had more complex data structures (at the very least, a hash / dictionary / associative array / key-value map) built into the language, as well as implicit memory management.

  Modern Day
  These days, the old hierarchy is apparently forgotten (much like minicomputers). I observe that there is generally a much simpler 2-tier classification :

  • Low level : C, assembly language
  • High level : absolutely every other programming language in wide use today

  I find myself wondering where C++ and Objective-C fit in this classification scheme. Then I remember that it doesn’t matter and this is all academic.

  Relevancy
  I think about this because I have pretty much stuck to low-level programming all of my life, mostly due to my interest in game and multimedia-type programming. But the trends in computing have favored many higher level languages and programming paradigms. I woke up one day and realized that the kind of work I often do — lower level stuff — is not very common.

  I’m not here to argue that low or high level is superior. You know I’m all about using the appropriate tool for the job. But I sometimes find myself caught between worlds, having the defend and explain one to the other.

  • On one hand, it’s not unusual for the multitudes of programmers working at the high level to gasp and wonder why I or anyone else would ever use C or assembly language for anything when there are so many beautiful high level languages. I patiently explain that those languages have to be written in some other language (at first) and that they need to run on some operating system and that most assuredly won’t be written in a high level language. For further reading, I refer them to Joel Spolsky’s great essay called Back to Basics which describes why it can be useful to know at least a little bit about how the computer does what it does at the lowest levels.
  • On the other hand, believe it or not, I sometimes have to defend the merits of high level languages to my low level brethren. I’ll often hear variations of, "Any program can be written in C. Using a high level language to achieve the same will create a slow and bloated solution." I try to explain that the trade-off in time to complete the programming task weighed against the often-negligible performance hit of what is often an I/O-bound operation in the first place makes it worthwhile to use the high level language for a wide variety of tasks.

    Or I just ignore them. That’s actually the best strategy.

• Ticket - changer l’assignation et le statut depuis un commentaire

  11 août 2011

  A la résolution d’un ticket, il est fréquent de laisser un commentaire à la suite afin d’expliquer la solution et les modifications effectuées.

  On exécute donc plusieurs actions en général, au moins 2, qui consistent à :

  • envoyer un commentaire ;
  • changer le statut du ticket ;

  On peut ajouter dans les formulaires de forums d’un ticket la possibilité de clore directement le ticket si on y est autorisé.

  Il suffirait d’ajouter un sélecteur de statuts dans le formulaire de forum si l’objet est ticket, de se baser sur les autorisations de modification du ticket en utilisant le pipeline recuperer_fond par exemple, et instituer le ticket à la validation du post par le pipeline traiter du form de forum.