Webcam init and get

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  • frakie
    #1

    Webcam init and get

    Hi there,
    I need a simple and stupid few line source code to access my webcam.
    I found lots of huge projects (c++ c and other) which are so big that
    they are impossible to be used.
    Does somebody know how to manage a webcam from it's basic functions?
    Where can i find a SIMPLE, VERY SIMPLE example project?
    Doesn't matter the what is the OS or the language, i just need it is
    easy portable source code...
    Tags: None
    • Walter Roberson
      #2
      Re: Webcam init and get

      In article <6bc54fd5-4290-4442-a004-a5c8e40f0414@a1 g2000hsb.google groups.com>,
      frakie <frakieack@gmai l.comwrote:
      >I need a simple and stupid few line source code to access my webcam.
      >I found lots of huge projects (c++ c and other) which are so big that
      >they are impossible to be used.
      >Does somebody know how to manage a webcam from it's basic functions?
      >Where can i find a SIMPLE, VERY SIMPLE example project?
      >Doesn't matter the what is the OS or the language, i just need it is
      >easy portable source code...
      You will not be able to find "easy portable source code", as
      not all systems provide enough functionality to be able to control
      webcams, or provide the functionality in very different ways.
      For example on the system I am using right now, it is possible to
      add a webcam... if you add in a digital I/O board, the webcam
      for which uses a 75 pin connector and transfers data in parallel.
      Meanwhile there are ethernet based webcams and USB based webcams
      and probably serial and parallel based webcams as well, all of which
      need to be controlled in very different ways.

      The most common webcams these days are ethernet based or USB based.

      The ethernet based ones are often accessible via TCP -- which requires
      that the system you are working on has a TCP stack, which is by no
      means guaranteed (though it is getting increasingly common except in
      some kinds of embedded systems.) The access to such systems is via
      an HTTP transaction; that does not require a full HTTP library, but
      does require an HTTP framework, complete with some MIME parsing.
      Typically to get an image, you would issue an HTTP GET against
      a particular file on the system and it would return it in encoded
      form. But controlling the camera would generally require HTTP POST
      transactions.

      The USB cameras... well, those require a USB interface library,
      which is going to be operating system dependant.


      You might find that someone has written Perl modules and posted
      them at cpan.org and you might find that those modules work
      for all of the kinds of systems you are interested in. But then
      you face the problem that installing Perl itself can be a bear of
      a job if you have to install it from source.
      --
      "Any sufficiently advanced bug is indistinguishab le from a feature."
      -- Rich Kulawiec

        Comment

        • frakie
          #3
          Re: Webcam init and get

          On May 12, 6:03 pm, rober...@ibd.nr c-cnrc.gc.ca (Walter Roberson)
          wrote:
          In article <6bc54fd5-4290-4442-a004-a5c8e40f0...@a1 g2000hsb.google groups.com>,
          >
          frakie <frakie...@gmai l.comwrote:
          I need a simple and stupid few line source code to access my webcam.
          I found lots of huge projects (c++ c and other) which are so big that
          they are impossible to be used.
          Does somebody know how to manage a webcam from it's basic functions?
          Where can i find a SIMPLE, VERY SIMPLE example project?
          Doesn't matter the what is the OS or the language, i just need it is
          easy portable source code...
          >
          You will not be able to find "easy portable source code", as
          not all systems provide enough functionality to be able to control
          webcams, or provide the functionality in very different ways.
          For example on the system I am using right now, it is possible to
          add a webcam... if you add in a digital I/O board, the webcam
          for which uses a 75 pin connector and transfers data in parallel.
          Meanwhile there are ethernet based webcams and USB based webcams
          and probably serial and parallel based webcams as well, all of which
          need to be controlled in very different ways.
          >
          The most common webcams these days are ethernet based or USB based.
          >
          The ethernet based ones are often accessible via TCP -- which requires
          that the system you are working on has a TCP stack, which is by no
          means guaranteed (though it is getting increasingly common except in
          some kinds of embedded systems.) The access to such systems is via
          an HTTP transaction; that does not require a full HTTP library, but
          does require an HTTP framework, complete with some MIME parsing.
          Typically to get an image, you would issue an HTTP GET against
          a particular file on the system and it would return it in encoded
          form. But controlling the camera would generally require HTTP POST
          transactions.
          >
          The USB cameras... well, those require a USB interface library,
          which is going to be operating system dependant.
          >
          You might find that someone has written Perl modules and posted
          them at cpan.org and you might find that those modules work
          for all of the kinds of systems you are interested in. But then
          you face the problem that installing Perl itself can be a bear of
          a job if you have to install it from source.
          --
          "Any sufficiently advanced bug is indistinguishab le from a feature."
          -- Rich Kulawiec
          Thank you very very much Walter!
          I know there must be an interface to interact with, but everything I
          found is really too confusing since each project is adding more
          functions than just init and getImage...
          I will try cpan.org Perl module, and I'll tell you! Really thanks!

            Comment

            • domen@coderock.org
              #4
              Re: Webcam init and get

              frakie  <frakie...@gmai l.comwrote:
              >I need a simple and stupid few line source code to access my webcam.
              >I found lots of huge projects (c++ c and other) which are so big that
              >they are impossible to be used.
              >Does somebody know how to manage a webcam from it's basic functions?
              >Where can i find a SIMPLE, VERY SIMPLE example project?
              >Doesn't matter the what is the OS or the language, i just need it is
              >easy portable source code...
              You might also want to look at Gstreamer. While the framework is
              portable, I don't know about webcam support for operating systems
              other than Linux (v4l2src worked great for me in some project).
              The big advantage is that changing from reading webcam stream to
              reading video file is just a few lines (and this can be very useful in
              testing!).

              Domen

                Comment

                • Stefano Sabatini
                  #5
                  Re: Webcam init and get

                  On 2008-05-12, frakie <frakieack@gmai l.comwrote:
                  Hi there,
                  I need a simple and stupid few line source code to access my webcam.
                  I found lots of huge projects (c++ c and other) which are so big that
                  they are impossible to be used.
                  Does somebody know how to manage a webcam from it's basic functions?
                  Where can i find a SIMPLE, VERY SIMPLE example project?
                  Doesn't matter the what is the OS or the language, i just need it is
                  easy portable source code...
                  You could consider using libavdevice from ffmpeg, video4linux and
                  video4windows should be supported, it is plain and portable C (but not
                  trivial to use, but that's the price you have to pay to deal with
                  multimedia).

                  Regards.
                  --
                  Stefano Sabatini
                  Linux user number 337176 (see http://counter.li.org)

                    Comment

                    • Walter Roberson
                      #6
                      Re: Webcam init and get

                      In article <slrng3tfk7.a3j .stefano.sabati ni@geppetto.rei labs.com>,
                      Stefano Sabatini <stefano.sabati ni@santefisi.ca os.org.invalidw rote:
                      >On 2008-05-12, frakie <frakieack@gmai l.comwrote:
                      >I need a simple and stupid few line source code to access my webcam.
                      >You could consider using libavdevice from ffmpeg, video4linux and
                      >video4window s should be supported, it is plain and portable C (but not
                      >trivial to use, but that's the price you have to pay to deal with
                      >multimedia).
                      http://cekirdek.pardus.org.tr/~ismail/ffmpeg-docs/v4l2_8c-source.html


                      #include "config.h"
                      #include "libavforma t/avformat.h"
                      #include <unistd.h>
                      #include <fcntl.h>
                      #include <sys/ioctl.h>
                      #include <sys/mman.h>
                      #include <sys/time.h>
                      #include <asm/types.h>
                      #include <linux/videodev2.h>
                      #include <time.h>


                      That's not portable C !

                      C89 3.8.2 Source File Inclusion
                      [...]
                      There shall be an implementation-defined mapping between the
                      delimited sequence and the external source file name. The
                      implementation shall provide unique mappings for sequences
                      consisting of one or more letters (as defined in 2.2.1) followed
                      by a period (.) and a single letter. The implementation may ignore
                      distinctions of alphabetical case and restrict the mapping
                      to six significant characters before the period.


                      Now "libavforma t/avformat.h" has more than six significant characters
                      before the period, so which, if any, file that will map to is
                      implementation-defined -- and thus not portable C.
                      --
                      "I like to build things, I like to do things. I am having
                      a lot of fun." -- Walter Chrysler

                        Comment

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