Flash RAM storage

Flash RAM storage is invading HDTV broadcasting. Sony is challenging Panasonic's P2 with its SxS. And tapeless camcorder pioneer Ikegami reinvented its decade-old nonlinear workflow model with the new GFPAK, while Thomson Grass Valley is finally shipping its CompactFlash-based Infinity camcorder. SeaChange has introduced the first major flash RAM video server. As a result, flash RAM looks like a winning format for the future.

Acquisition format wars

Format choices in TV broadcast field acquisition have traditionally been between Panasonic and Sony. Historically, when discussing professional and broadcast field acquisition formats, the focus was generally much more about video compression formats than about the recording media, because both companies were recording to tape cassettes, although not compatible ones.

Sony had early successes with Betacam and Digital Betacam, while Panasonic came on strong in the late 1990s with DVCPRO and DVCPRO-50,and then DVCPRO-HD in 2001. Sony successfully introduced DVCAM, SX and IMX in the mid- to late-1990s, but those formats didn't threaten to surpass Panasonic for TV station applications. As recent as 2003, the industry was still using videotape cassettes for field acquisition storage.

At the 2004 NAB show, Sony delivered XDCAM SD camcorders recording to a new technology: removable optical disc cartridge. There wasn't a tape cassette in sight. Sony was clearly betting on its emerging optical disc technology and proprietary Professional Disc (PD) for future camcorder field acquisition storage. We learned later that this was part of the company's Blu-ray disc development.

In 2004, Panasonic showed its flash RAM card technology named P2, based on the CardBus interface standard developed primarily for laptop computers. The company's implementation also used proprietary hardware and software to support its needed functionality, but with one nonproprietary feature — it relied on a standard PC interface port as the physical connection.

The posturing of the two giants had started. Which technology would replace the tape cassette in camcorder field acquisition in the longer term: optical disc or flash RAM storage? After all, for many years, all professional camcorder manufacturers used videotape cassettes as a common storage media. It is reasonable to project that our industry will soon adopt one common storage media as the dominant tape cassette replacement, not two.

In 2005, Sony introduced its first professional HD camcorder recording to the PD (XDCAM HD models). At the same time, Panasonic unveiled its first professional HD camcorder recording to P2 (HVX200). Also in 2005, Thomson Grass Valley announced the Infinity camcorder using the cost-effective consumer market CompactFlash memory card. For nonstorage reasons, the Infinity cameras didn't begin shipping until late 2007.

Let's not forget that in 1995, Ikegami was the first major camcorder manufacturer to introduce a nonlinear acquisition-to-edit workflow (EditCam), working with Avid, and using a removable hard disk module attached to its field cameras. Ikegami has recently teamed up with Toshiba to reinvent the EditCam nonlinear workflow using removable flash RAM modules called GFPAK (GigaFlash).

The battle for market share wasn't just about compression formats, but more about acquisition-to-edit portable storage formats. While many agreed that the era of videotape cassettes was quickly diminishing, few could decide if the optical disc would beat the flash RAM card as the ultimate acquisition-to-edit remove-and-replace storage technology. This resulted in two camps of users by 2006 — one for the Sony PD optical disc and the other for Panasonic's flash RAM card technology supported by Thomson Grass Valley and Ikegami.

Behind the PD optical

Since the dawn of camcorders, Panasonic and Sony have battled for the lead in the professional video market largely based on proprietary formats and technologies. The most basic reason for manufacturers developing proprietary solutions is that once the user installs a proprietary compression and/or storage format, the user is generally locked in to that decision for several years because of the high-cost threshold of format change and re-entry.

Several years ago, if you considered flash RAM for camcorder remove-and-replace storage, you may have experienced a possible long-term weakening in your proprietary hold. But no one can second guess Sony's business considerations for its original decision to incorporate the PD optical disc cartridge as the removable media in professional camcorders.

With the recent availability of XDCAM EX with SxS (solid-state storage), is Sony sending a message to TV broadcasters that it is altering course? Although well-suited for remove-and-replace HD camcorder acquisition storage, Sony's PD optical disc cartridge, with its proprietary mechanical drive requirements and relatively limited write/read bit rates as compared with flash RAM cards, is now better used as longer term on-the-shelf nonlinear storage. Its random access performance beats the linear tape cassette.

New HD camcorders

Immediately after the 2007 NAB, Sony announced its cooperation with flash RAM market leader SanDisk to bring the SxS flash RAM cards to market specifically for professional video camcorder acquisition applications. This was obviously in direct competition with Panasonic's established P2 flash memory card technology.

Then, at the September 2007 IBC convention, Sony unveiled its new XDCAM EX HD camcorder line using the new SxS flash RAM cards. Simultaneously, SanDisk announced the availability of SxS cards. The XDCAM EX has been shipping for several months, with SxS cards available in 8GB and 16GB sizes.

Another interesting point: Looking at Sony's suggested XDCAM EX workflow, the company is (not surprisingly) recommending using the PD optical disc media for long-term and archival storage. Prolonging the lifespan of the PD product line makes sense for existing Sony PD customers, as they have already invested in PD recorder/players and other related PD-friendly subsystems.

CardBus PC Card or ExpressCard?

Panasonic's P2 is based on an older technology CardBus PC Card, while Sony's SxS uses the newer ExpressCard technology. Both standards were originated and promoted by the Personal Computers Memory Card International Association (PCMCIA). The CardBus plug-in slot standard was originally introduced by the PCMCIA in 1990. Numerous updates and improvements were made through 2001, when further standard developments stopped. The final CardBus technology allows PC Cards and hosts to use 32-bit bus mastering and operate at clock speeds up to 33MHz. The connectivity relies on a computer's PCI bus, but not on the new and faster PCI Express.

PCMCIA developed the ExpressCard standard to carry forward the benefits of plug-in I/O cards to the next generation of personal computing devices. The potential benefit of ExpressCard technology over the older CardBus PC Card is a dramatic increase in bandwidth. This is because the ExpressCard uses a direct connection to the system bus over a PCI Express lane and USB 2.0, while the CardBus uses an interface controller that only interfaces with the previous generation PCI bus. The ExpressCard has a maximum throughput of 2.5Gb/s through the PCI Express lane and 480Mb/s through USB 2.0 versus the CardBus' shared 1.04Gb/s bandwidth.

ExpressCard promoters also claim other advantages, including lower cost, better scalability, lower power consumption and better integration with current and future motherboard chipset technology. Unfortunately, the ExpressCard interface is not backwards plug-compatible with CardBus devices. Thus new PCs may need an ExpressCard/CardBus adapter in order to accept P2 cards. One certainty is that future PC workstations, whether desktops or laptops, will generally not incorporate CardBus slots, but will likely favor ExpressCard slots.

The bottom line on theoretical maximum media transfer speed (from RAM card to workstation or server through a plug-in slot) seems to be 800Mb/s with the SxS platform and 640Mb/s with the P2 platform. On the surface, it appears this is not a great difference in transfer rates. However, the actual maximum transfer speed depends on the specific implementations by Panasonic and Sony.

Real differences: compression formats

The real operational differences become more apparent when comparing Panasonic and Sony's HD camcorder compression formats and the resulting bit rates. Transfer times for a given file are usually specified as X times faster than real time. The real-time transfer time of one minute of video is, of course, one minute whether the program is compressed to 35Mb/s or 100Mb/s. But, through a given broadband pipe, there is the potential to transfer a compressed lower bit rate video file faster than a compressed higher bit rate video file of the same real-time duration.

In its high-quality mode, Sony's XDCAM EX camcorder compresses HD video to 35Mb/s VBR in an MPEG-2 long GOP format. Let's say this produces a gross average rate of 40Mb/s, including overhead and audio. Presuming that the SxS sustained system transfer bandwidth is 500Mb/sat best, Sony can transfer material at more than 10X real-time speed, meaning a 10-minute program can be transferred in less than one minute.

Panasonic's direct price range competition to Sony's EX are the HVX-200 (less expensive) and the HPX-500 (more expensive). Both Panasonic models offer DVCPRO-HD compressed to a gross rate of about 120Mb/s.

Presuming the P2 sustained system transfer bandwidth is 400Mb/s at best, Panasonic can therefore transfer material at 3.3X real-time speed. This means that a 10-minute program can be transferred in about three minutes, which is about three times slower than that of Sony's XDCAM EX platform using SxS memory. This is primarily due to Sony's much lower bit rate for its MPEG-2 long GOP compressed format, which is only about one-third of Panasonic's intraframe DVCPRO-HD compressed bit rate. Panasonic's new AVC-Intra-50Mb/s format, available in more expensive camcorders, improves the transfer time to about 6X real-time speed, but is still slower than Sony's SxS. Actual trials may produce different results.

But wait; that's not the total picture. We also need to look at storage capacity and media price. Table 1 on page 48 illustrates several key parameters for the four manufacturers currently offering HD camcorders with flash RAM removable storage.

Considering real-time storage capacity and fast workflow potential, Sony's SxS appears fastest. However, this is because of the company's long GOP codec format, while Panasonic and Thomson Grass Valley only offer intraframe formats. Ikegami offers selectable long GOP and intra MPEG-2. The SxS technology, with its extremely wide write/read bandwidth, now enables Sony to introduce a range of professional HD camcorders based on new competitive intraframe HD codec technology, if Sony chooses to do so.

I believe that flash RAM storage for professional video use will eventually settle on common formats of media and connectivity, as is currently championed by Thomson Grass Valley in its use of the widely available and highly competitive CompactFlash memory cards. The bottom line is that we may finally be able to forget about tape cassettes all together, because they will be replaced by flash RAM cards.

Tore B. Nordahl is principal of nordahl.tv, a Los Angeles-based consulting firm delivering HDTV technology reporting, product strategy and market research services.

Table 1. This table compares four HD camcorder manufacturers that have introduced flash RAM card technology for field acquisition storage in the broadcast environments. Flash RAM card comparison Ikegami Panasonic Sony Thomson Grass Valley Flash RAM product nameGFPAKP2SxSCompactFlashCapacity in GB 16/32/64 8/16/32/64 8/16/32 16/32/48 Street price (as of March 2008) $900 (32GB) $900 (16GB) $875 (16GB) $180 (32GB) Price per GB $28 $56 $55 $6 HD capacities in minutes 60 (32GB) 16 (16GB) 50 (16GB) 32 (32GB) Price per minute for HD $15 (32GB) $56 (16GB) $17 (16GB) $6 (32GB) High-quality compressed HD gross bit rate (video only) 50Mb/s 100Mb/s 35Mb/s 100Mb/s HD compression format for highest quality mode MPEG-2long GOP DVCPRO-HDAVC-Intra-100both intraframe EX HQMPEG-2long GOP JPEG2000 intraframe Maximum estimated transfer speed faster than real time(file transfer) More than 5X More than 3X More than 10X More than 2.5X Estimated maximum actual transfer bit rate (best case read in actual workflow) 260Mb/s USB 400Mb/s 500Mb/s 300Mb/s Bus technology SATA (internal) USB (external) CardBus ExpressCard CompactFlash