drhoff:
The thing I wanted to do differently was to be able to save codes and play them back without having to know the protocol.
In that case, other than altering the quanta (0.1 millisecond seems to be the smallest quanta you could ever encounter), there isn't much you can do to compress the data. Huffman coding may provide some compression.
but he is using 50uS resolution for recording codes...
As I said above, I suspect 500 uS is adequate but...
...I'd need to mess around with more devices to see if that is always enough precision.
...is certainly worth doing.
I'm really thinking I'll need external storage of some kind. Any suggestions on that?
Flash-drive (as GoForSmoke mentioned), FRAM (CrossRoads' favourite), EEPROM (external; Atmel sells these).
All three are available with SPI communications. The latter two are available with I2C communications. I would look for something with an existing Arduino library.