I spend some time to day at a CES sideshow with a rep from the SD Association. These are the guys who iron out the details of this particular type of memory card to ensure compatibility across many different brands and manufactures. SD format makes up 77% of the memory card market, so if you are looking for the most compatible and now definitely the most technologically advance, SD should always be your choice. Sony comes in a distant second with 12% of the share, followed by Compact Flash (6%), MMC (3%), and xDP (2%).
Due to limitations on transfer speeds and file systems SD has gone though a few upgrades. The first know as simply SD maxed out at 2GB. SDHC allowed for larger memory access of 32GB. Now SDxc maxes out at a whopping 2TB which should hopefully hold us over for a few years. This new standard uses exFAT file system or sometimes called FAT64. In addition to larger capacities SDxc will allow for higher theoretical speeds of up to 300mbps as opposed to 104mbps of SDHC.
The good news is that SDxc will have the same SD and microSD format- they have dropped miniSD for this new SDxc standard. New devices supporting SDxc will be backwards compatible with all your SD and SDHC cards. The bad news is that unlike the transition from SD to SDHC, which sometimes only required a firmware update, requires supporting chipsets. So don’t expect to simply firmware upgrade your current player for this new format.
The SD Association has been working closely with manufactures so will start to see new devices trickle out in 2009 and more of a heavier roll out in 2010. These capacities will start at 32GB and up, but there is no telling when the theoretical 2TB limit will be hit.
So what does this mean for MP3 players? You current hardware will be left in the dark, but I would suspect SanDisk to be the first to move on this new format. I would not be surprised if their next gen of players supported SDxc.