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Garmin jnx file format hacking

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  • #16
    Re: Garmin jnx file format hacking

    Hi there,

    Right now, I'm studying five unidentified header fields at offsets 1C-2F.
    It seems that two DWORDs at offset 1C and 20 contain the subscription expiration date and time respectively.
    To confirm that and to find out their format, I need some help from you.

    Could you please post here or send me to PM you subscription expiration date, and the hex values of the fields 1C and 20 from a couple of your JNX files?
    Thanks in advance!
    Garmin GPSMAP 62s

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    • #17
      Re: Garmin jnx file format hacking

      Hi whiter i dont currently have a subscription but i was planning on getting a birdeye select account tomorrow. post to you I a short while

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      • #18
        Re: Garmin jnx file format hacking

        EB 3D 3F 29 00 00 00 00 in three different files
        05.12.2011 is my BirdsEye expiration date

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        • #19
          Re: Garmin jnx file format hacking

          JNX format description in English.

          BTW, I've updated it a little.
          Last edited by Whiter; 10th December 2010, 10:07.
          Garmin GPSMAP 62s

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          • #20
            Re: Garmin jnx file format hacking

            Originally posted by xxakep View Post
            EB 3D 3F 29 00 00 00 00 in three different files
            05.12.2011 is my BirdsEye expiration date
            In this case, this is the number of seconds since December 30, 1988, 12:00 PM.
            But I cannot recognize this as any standard date/time format
            Garmin GPSMAP 62s

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            • #21
              Re: Garmin jnx file format hacking

              Originally posted by Whiter View Post
              In this case, this is the number of seconds since December 30, 1988, 12:00 PM.
              But I cannot recognize this as any standard date/time format
              I have
              71 58 FE 27 00 00 00 00
              in 4 different files. To see whether you got the algorithm right, what do you calculate for the expiry date? (I'll let you know after your guess)
              Last edited by gaga55; 10th December 2010, 15:01.

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              • #22
                Re: Garmin jnx file format hacking

                Originally posted by gaga55 View Post
                I have
                71 58 FE 27 00 00 00 00
                in 4 different files. To see whether you got the algorithm right, what do you calculate for the expiry date? (I'll let you know after your guess)
                I've made a mistake in the message above. Not since December 30, 1988, but since December 30, 1989.

                If I got it correctly, then your subscription will expire on April 5, 2011. Am I right?
                Garmin GPSMAP 62s

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                • #23
                  Re: Garmin jnx file format hacking

                  That's right!
                  However, while Garmin myMaps (online) gives April 5 2011, Basecamp says April 6 2011.

                  I hope you make further progress, I'd love to be able to make jnx files from any image file.
                  Thanks for your effort.

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                  • #24
                    Re: Garmin jnx file format hacking

                    HI Guys,

                    I'm the developer of MAPC2MAPC. Maybe I can add creation of JNX files to it. But I don't have a Garmin Unit and may need someone who I can send test files to - if I get that far! Any volunteers?

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                    • #25
                      Re: Garmin jnx file format hacking

                      Originally posted by roger47 View Post
                      I'm the developer of MAPC2MAPC. Maybe I can add creation of JNX files to it.
                      That would be great!


                      Originally posted by roger47 View Post
                      But I don't have a Garmin Unit and may need someone who I can send test files to - if I get that far! Any volunteers?
                      I'd gladly help you with testing.
                      Garmin GPSMAP 62s

                      Comment


                      • #26
                        Re: Garmin jnx file format hacking

                        If we're creating maps, what is the downside of making them all 'demo' maps - with zero expiration dates, control codes etc? It would make the task easier. And does anyone know the map projection used for the 'tiles' : are they Mercator (like Google Maps and most 'mobile atlas') or Plate Carree like Google Earth

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                        • #27
                          Re: Garmin jnx file format hacking

                          Originally posted by roger47 View Post
                          HI Guys,

                          I'm the developer of MAPC2MAPC. Maybe I can add creation of JNX files to it. But I don't have a Garmin Unit and may need someone who I can send test files to - if I get that far! Any volunteers?
                          Hi,

                          I'm volunteer to do any tests! :-)

                          I have an Oregon 450.

                          Bill.

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                          • #28
                            Re: Garmin jnx file format hacking

                            Wooh Project seems to realy taking off now.

                            Roger i have and oregon unit and i am willing to test files for you. I can only see 1 problem with setting the them all to demos maps.

                            When basecamp outputs a demo map it limits is viewable area size. This may also be a limitation in the firmware of the unit. I suggest we try a large file with and with out a zero expriation date.

                            Havent a clue what the projection is.

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                            • #29
                              Re: Garmin jnx file format hacking

                              Originally posted by roger47 View Post
                              If we're creating maps, what is the downside of making them all 'demo' maps - with zero expiration dates, control codes etc?
                              The device shows only one demo map, and refuses to load all other.


                              Originally posted by roger47 View Post
                              And does anyone know the map projection used for the 'tiles' : are they Mercator (like Google Maps and most 'mobile atlas') or Plate Carree like Google Earth
                              Is there any easy way to identify this?
                              I can make a JNX with some specific coordinates, and then check what values are in the file.
                              Garmin GPSMAP 62s

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                              • #30
                                Re: Garmin jnx file format hacking

                                I've take the demo.zip that Whitedragon posted on 4th. I've decoded the fields and built the JPGs - seems to be an airfield.

                                I'll try and build one later as a 'demo' just to prove the principle.

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