4 replies to this topic

[Barbez95]

Good morning,

I use the Netduino helpers VC0706.cs class, I modify the function "TakePicture" which doesn't need anymore a path to save the image on the Netduino Plus but it sends bytes via TCP/IP.  

I retrieve bytes from the camera buffer, but I can't convert them into a base64 string because a few of them are equal to '!' and '*' characters which aren't supported by the base64 standard, so I can't rebuild the base64 string as an image with a memory stream... Any ideas?

Thanks for your help!

[CW2]

How exactly are you converting the source string? Base64 is not simple substitution, it converts three octets (bytes) into four 6-bit encoded characters, using some bit manipulation.

[Barbez95]

Yes, we get a byte array (length 120) from the camera buffer and we convert it into a base64 string format via the static method "ToBase64String" in Convert class. The issue is that in the final string we get characters that are not valid for a base64 string. The conversion is correctly handled i think...My doubt is about the buffer: being a jpeg stream, once frozen, could it contain bytes with a value > of 63? And, if it isn't possible, maybe i've got a dirty read? Could it be solved by the use of a shielded wire on TX pin?

[CW2]

Ok, thanks for the clarification. This was fixed in .NET Micro Framework 4.3 (see Issue #1388), you can set Convert.UseRFC4648Encoding property in order to get '+' and '/' instead of '!' and '*':
 

System.Convert.UseRFC4648Encoding = true;

[Barbez95]

Thanks for the reply! I will try in these weeks because I'm in holiday! And thank you again!