Mike Schell
May 17th, 2008, 11:05 AM
After considerable research, we can now recommend the following Compact Flash (CF) cards for Flash XDR:
Transcend 32GB 133X - Data-rates up to 100 Mbps
Transcend 16GB 300X - Data-rates > 100 Mbps
The 32GB card is widely available for around US $150 to $165, while the 16GB card is just starting to hit the retail market at US $240. On a GB basis, the 32GB card is 1/10 the price of other professional solid-state media.
CF speed ratings are based on the old audio CD rate of 1X = 150 KBytes/sec, so 133X = 20 MBytes/sec (or 160Mbps) and 300X = 45 Mbytes/sec (or 360 Mbps). But be aware that this number often refers to the read speed and not the write speed (which is normally lower).
The Transcend 133X 32GB card is a real performer, with read speeds of 41 Mbytes/sec (275X) and write speeds of 16.6 Mbytes/sec (110X). The 300X 16GB, on the other hand, is an absolute screamer with read and write speeds of almost 50 Mbytes/sec (333X).
Both cards employ UDMA (Ultra DMA) read and write transfer protocol. The 32GB card uses UDMA-4, while the 16GB card uses the newer UDMA-5. UDMA enables long burst transfers of up to 128 KBytes without host intervention. On our Flash XDR, all video and audio transfers to and from the CF cards are handled in hardware, for the absolute fastest possible performance. (No dropped frames).
As data is written (or read) to the CF card, a 16-bit CRC (cyclic redundancy check) is generated over every 512 bytes by both the controller (Flash XDR) and the CF card. These CRCs are continuously compared to ensure reliable data transfers. Any errors are reported to the user on the LCD screen (in flashing text!)
The 32 GB card uses multi-level cell (MLC) technology, which stacks 2-bits of memory in a single cell site. The higher-performance 16 GB card employs a single-level cell (SLC) design with 1-bit per cell site. Clearly the MLC approach allows designers to cram more bits into a given area of silicon at the cost of lower access speeds (the write times are 2x to 3x that of the SLC design). Naturally, the MLC NAND Flash is about 1/2 the cost of SLC.
The NAND Flash memory found in Compact Flash cards is exactly the same memory found in iPods, iPhones, Cell Phones, P2 / SxS cards, and Solid-State Hard Drives. The only difference is the controller interface (CF and P2 cards uses a parallel interface, while SxS uses a serial interface). Over the the last 4-5 years, Flash memory prices have been declining at the rate of 40 to 50% per year. There is every indication that this trend will continue into the foreseeable future.
Compact Flash offers relatively low-cost, very low power consumption (compared to hard-drives or tape drives), no moving parts, very long-life, small size and fast read and write access. They can be hot-swapped for endless record times. And to keep the costs low, CF cards are widely available from multiple vendors.
Unlike hard-drives, which exhibit slower read and write access as they become full, Compact Flash offers very uniform performance no matter has much data is on the card. CF also offers faster than real-time read performance. Using the 32G card and recording at 50Mbps, you can transfer the data via a Firewire-800 reader at rates up to 41 Mbytes/sec or more than 6X real-time. So you can easily edit directly from the CF card, although it's best to use a hard-drive to store your project.
I think one of the most exciting features of the CF interface design on Flash XDR is the ability to record to two cards simultaneously (RAID-1). Using Compact Flash it's now economically feasible to record the same video to multiple cards. So after a shoot, you can instantly hand off one card to the editor and another card to the director/producer. Or you can lock up one card as a backup and send the second card to post. (Try doing that with a tape deck!)
I'll have another post shortly on recommended CF card readers.
Mike Schell
Transcend 32GB 133X - Data-rates up to 100 Mbps
Transcend 16GB 300X - Data-rates > 100 Mbps
The 32GB card is widely available for around US $150 to $165, while the 16GB card is just starting to hit the retail market at US $240. On a GB basis, the 32GB card is 1/10 the price of other professional solid-state media.
CF speed ratings are based on the old audio CD rate of 1X = 150 KBytes/sec, so 133X = 20 MBytes/sec (or 160Mbps) and 300X = 45 Mbytes/sec (or 360 Mbps). But be aware that this number often refers to the read speed and not the write speed (which is normally lower).
The Transcend 133X 32GB card is a real performer, with read speeds of 41 Mbytes/sec (275X) and write speeds of 16.6 Mbytes/sec (110X). The 300X 16GB, on the other hand, is an absolute screamer with read and write speeds of almost 50 Mbytes/sec (333X).
Both cards employ UDMA (Ultra DMA) read and write transfer protocol. The 32GB card uses UDMA-4, while the 16GB card uses the newer UDMA-5. UDMA enables long burst transfers of up to 128 KBytes without host intervention. On our Flash XDR, all video and audio transfers to and from the CF cards are handled in hardware, for the absolute fastest possible performance. (No dropped frames).
As data is written (or read) to the CF card, a 16-bit CRC (cyclic redundancy check) is generated over every 512 bytes by both the controller (Flash XDR) and the CF card. These CRCs are continuously compared to ensure reliable data transfers. Any errors are reported to the user on the LCD screen (in flashing text!)
The 32 GB card uses multi-level cell (MLC) technology, which stacks 2-bits of memory in a single cell site. The higher-performance 16 GB card employs a single-level cell (SLC) design with 1-bit per cell site. Clearly the MLC approach allows designers to cram more bits into a given area of silicon at the cost of lower access speeds (the write times are 2x to 3x that of the SLC design). Naturally, the MLC NAND Flash is about 1/2 the cost of SLC.
The NAND Flash memory found in Compact Flash cards is exactly the same memory found in iPods, iPhones, Cell Phones, P2 / SxS cards, and Solid-State Hard Drives. The only difference is the controller interface (CF and P2 cards uses a parallel interface, while SxS uses a serial interface). Over the the last 4-5 years, Flash memory prices have been declining at the rate of 40 to 50% per year. There is every indication that this trend will continue into the foreseeable future.
Compact Flash offers relatively low-cost, very low power consumption (compared to hard-drives or tape drives), no moving parts, very long-life, small size and fast read and write access. They can be hot-swapped for endless record times. And to keep the costs low, CF cards are widely available from multiple vendors.
Unlike hard-drives, which exhibit slower read and write access as they become full, Compact Flash offers very uniform performance no matter has much data is on the card. CF also offers faster than real-time read performance. Using the 32G card and recording at 50Mbps, you can transfer the data via a Firewire-800 reader at rates up to 41 Mbytes/sec or more than 6X real-time. So you can easily edit directly from the CF card, although it's best to use a hard-drive to store your project.
I think one of the most exciting features of the CF interface design on Flash XDR is the ability to record to two cards simultaneously (RAID-1). Using Compact Flash it's now economically feasible to record the same video to multiple cards. So after a shoot, you can instantly hand off one card to the editor and another card to the director/producer. Or you can lock up one card as a backup and send the second card to post. (Try doing that with a tape deck!)
I'll have another post shortly on recommended CF card readers.
Mike Schell