max/msp to ruby via udp message format

Question

I'm trying to build a little GUI with max/msp for a ruby project I can't find a way to properly convert the data i receive form max.

here is several examples of message that i've received from max in ruby (i've send 2 first then 1 0 -1 -2):

["int\x00,i\x00\x00\x00\x00\x00\x02", ["AF_INET", 53802, "127.0.0.1", "127.0.0.1"]]
["int\x00,i\x00\x00\x00\x00\x00\x01", ["AF_INET", 53802, "127.0.0.1", "127.0.0.1"]]
["int\x00,i\x00\x00\x00\x00\x00\x00", ["AF_INET", 53802, "127.0.0.1", "127.0.0.1"]]
["int\x00,i\x00\x00\xFF\xFF\xFF\xFF", ["AF_INET", 53802, "127.0.0.1", "127.0.0.1"]]
["int\x00,i\x00\x00\xFF\xFF\xFF\xFE", ["AF_INET", 53802, "127.0.0.1", "127.0.0.1"]]

so far i've been able to convert positive values to integer via String#ord or String#unpack but with those methods negative integers gives me 0 value

what's the issue , i am not getting... share your code please. — Arup Rakshit, Jun 23 '13 at 11:11
i just want to know how to convert first part of the message ("int\x00,i\x00\x00\xFF\xFF\xFF\xFF") to integer in ruby, do you know how to do that? — szymanowski, Jun 23 '13 at 11:33
Is this `"int\x00,i\x00\x00\x00\x00\x00\x02".ord # => 105` you want ? — Arup Rakshit, Jun 23 '13 at 11:35
the five messages in my question are received when i'm successively send 2, 1, 0, -1, -2 from max/msp. i just want to convert back to integer — szymanowski, Jun 23 '13 at 11:38

score 2 · Accepted Answer · answered Jun 23 '13 at 11:42

You can easily do it with #unpack, using offset ('@8'), and 32-bit signed bigendian int ('l>')

str.unpack('@8l>')

I'm not sure what initial part of string means ("int\x00,i\x00\x00") and I have just ignored it with offset. It might need additional fiddling, if there is any important data.

max/msp to ruby via udp message format

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