You can choose how much correction you get, in terms of how many bit errors you can correct per 'n' bits. And you need surprisingly few bits to get pretty great

You can choose how much correction you get, in terms of how many bit errors you can correct per 'n' bits. And you need surprisingly few bits to get pretty great performance under "reasonable" bit-error rate channel (like under 10% overhead). You can wind up the strength of the error correction if you anticipate a noisier channel. QR codes have 4 levels of correction you can use depending on how robust you wish them to be. CDs and DVDs use two chained, fixed, levels to keep the decoders simple. CDs have 25% overhead, but their correction is very strong: they can correct 4000 bits in a row.