What is the exact speed specification?

The Blu-ray.com FAQ says that 1x is 36Mbps; 1.5x is 54Mbps; 2x is 72Mbps.
What, precisely, does that mean? 36,000,000 bits, or 37,748,736 bits?
I mean, is M a million (1000000) or 2^20 (1048576)?
Thank you!

[jorg]

im gusseing it will like hard drive to manufacturing the stander is 000000s but with the other thing it is a scentifict standerd(programing)

[dialog_gvf]

Discs, HDD and related transfer rates use decimal (10^x) values. Memory is still binary (2^n).

So, for BD discs, capacity and bandwidth are measured in decimal quantities. So, 50GB = 50 x 10^9 bytes and 36Mbps = 36 x 10^6 bits per second (36Mbps)

And for BD 1x == 36Mbps.
BD-Video requires a 1.5x drive (54Mbps)
Most BD burners are 2x (LG's is 4x).

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It is no longer proper to use kilo, mega, and giga to mean 2^10, 2^20, and 2^30 respectively. Computing misused the decimal prefixes which were defined under SI, which has lead to the confusions.

In 1999 the IEC (International Electrotechnical Commission) introduced new binary prefix designations to correct the misuse:

kibi (Ki): 2^10
mebi (Mi): 2^20
gibi (Gi): 2^30

Gary

Thanks, Gary. I always use the proper prefixes myself.

[DavePS3]

Anyone know what specs on a disc transfer dictate how smoothly the film judder runs - or is there any difference? Are there specs on the back of a clamshell that tell you so you know what titles are more likely to have less judder?