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• Push RTSP over HTTP

  27 juin 2017, par Type11

  I need to make an emulator of cameras we have streaming to a video recording platform we created.

  The camera I am trying to emulate makes use of RTSP over http (well https but we can ignore that for now) which is somewhat normal but it doesn’t do the pull variety it does a push (we give the camera a url and it starts pushing to the video recording server).

  I have been using ffmpeg which has an rstp over http implementation but it is the pull kind where you take the client and give it a url to pull from.

  I have hacked around and gotten it to send an http GET as expected with the right headers we expect in it which our server uses and recognizes then it times out before streaming anything which makes sense as I think it is waiting for our server to send something.

  I could keep going down this path but I wanted to know if anyone else had run into this and if there was any prebuilt java, c, or c++ library that does anything like this I could start from ? I have searched around but most everything appears to be for a pull model.

  this is a capture of what the camera is sending (there is more but it is just more of the video stream below). this is the full tcp conversation.

  RTSP/1.0 200 OK
  Host : 192.168.1.9
  User-Agent : RS/E060660C84EB
  Content-Type : application/octet-stream
  X-SDP : 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
  X-Precapture : 8
  Authorization : Basic QXZ3R3VhbXpRcG15eUx3anlGYlZQS1ZCL2hoc1prWXltVVo0Q3cwb2FHaWZSWlBrNmhSRkVySFZoUkoxSG9lVjo2SWZTQ3VyYVRVT0FoU2RmVkJLdDBnQUFBQUFBQUFBQUFBQUFBQUFBQUFBaVNyTFFzK2tJNEVISVB5ZG9aL1Vu

  $...........}..|.....?.....a..@.P..    ..c.0.....<.>H ......Zas...AQZ...:.?W..A..q2..~.C..4.7....H’....*.....6 ?...........K.k.q...S.e+[g.......o... ..C1_[....N..........?.q.9.s..>..Gk.........[....&....n ;c..0c....#.A...9
  ......q...]...B...W.....8."....[..\c(..?Z.F !. 9. ..e...

  %..0.p2.h.0.,.'g.Rf.\s......@j. .....0.............H.V
.K{EL
M.ig..;i...PS..?..~HR..?ID>....T.Ie.m....
.....!..hBk..P-uX.V&...^<.ab....s....|.#.z...e..O+.{.!.0code>b..Q._d...z.......l.

  ...

  Any help on a library that might send a stream like this would be appreciated.

• FFMPEG - changing pixel format from 24-bit RGB to 8-bit Grayscale only changes color, but not file size

  27 septembre 2018, par Minjun Seong

  I am using the avlib* libraries and currently using the sws_getContext function to change pixel format from RGB (AV_PIX_FMT_RGB24) to grayscale (AV_PIX_FMT_GRAY8). The expected behavior should have been that the output file size should have decreased by 3 times as we are going from 24 bit rgb to 8 bit grayscale, but it stayed the same. Furthermore, when I checked on Media-Coder to see the format, the video format was still RGB. Any ideas on why the file size didn’t change and why the file format is still RGB ?

  Note : the video DID change to black and white as expected.

• How Many Default Languages ?

  26 janvier 2012, par Multimedia Mike — Programming

  I was thinking back to my childhood, when my family first owned a computer. It was an MS-DOS-powered IBM PC. The default OS came with 2 programming environments, such as they were : GW-BASIC and batch files. It was a start, I suppose. I guess most any microcomputer you can name from that era came with some kind of BASIC interpreter. That defined the computer’s “out of the box” programmability.

  Then I started wondering how this compares to computers (operating systems/distributions, really) these days. So I installed a fresh version of the latest Ubuntu Linux version (11.10 as of this writing ; x86_32) and looked for programmability (without installing anything else). This is what I came up with :

  1. gcc/C (only the C compiler ; other components of the GNU compiler collection are installed separately)
  2. Perl
  3. Python
  4. C#, as furnished by Mono
  5. Bash — can’t forget about the shell as a full-featured programming language (sh is also present, but not t/csh)
  6. JavaScript — since Firefox is installed per default, JS counts
  7. GNU Assember — thanks to Reimar for the reminder that if gcc is present, gas necessarily needs to be there as well

  I checked on C++, Objective C, Java, Ada, Fortran, Go, Lua, Ruby, Tcl, PHP, R and other languages I could think of, but the above items were the only ones present by default. At the same time, I checked my Mac OS X (10.6) box and it also has Ruby and PHP installed. It has a bunch of other languages, courtesy of Xcode, so I can’t certify anything about its out of the box programmability.

  Still, I think “embarrassment of riches” pretty well sums it up. I try not to be crotchety old fogey complaining that kids these days don’t know how good they have it ; rather, I’m genuinely excited for anyone who wants to leap into computer programming in this day and age.