Gyscos schrieb:
> Isn't there some bars at the beginning or the end that indicate the encoding ?

No, not really. Though many barcodes include some "frame" to (a) 
identify the side at which the barcode starts, and/or (b) calibrate for 
the size of the barcode; such frames can often double-act to prevent 
misinterpreting other barcode types.

For instance, Code39 IIRC always starts and ends with the bars it uses 
for the Asterisk (*).

EAN-13, on the other hand, uses one pair of simple bars at the 
beginning, end, and in the middle, respectively, to calibrate for size, 
while the reading direction can unambiguously be inferred from any 
"character" of the barcode "payload".

But these "frames" are only standardized for each individual barcode 
type, and there is no universal scheme to identify the type. All you can 
do is test for which types of barcode this particular specimen reads 
without error.

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