MPEG 2 Die For........................................
newmedia.com
DVD Brings MPEG 2 to the Forefront
By Cliff Roth
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PRODUCT
TABLE MPEG 2 Encoders
A full breakdown of product features, prices and contact information.
Now that DVD is here in force, MPEG 2 encoders are proliferating. A year or two ago, most MPEG 2 encoding was done in service bureaus on $100,000-plus systems. Now you can buy excellent software encoders (albeit not real-time) starting at just $495, and real-time hardware begins at $5,000. Virtually all MPEG 2 encoders are also capable of MPEG 1 encoding, so you can use them for most digital video purposes.
Digigami MegaPEG<Picture: digigami>ÿÿÿ<Picture>ÿÿ MPEG 2's case is further helped along by faster CPUs in playback machines, which eliminate the need for special decoding hardware. Software MPEG 2 decoding is quite workable for the latest Pentium MMX and Pentium II workstations. And DVD upgrade kits for older machines typically include decoding hardware, so developers are virtually assured that if a computer has a DVD-ROM drive, it also has MPEG 2 decoding capability.
ÿÿÿ<Picture>ÿÿ If you only have small bits of video to encode, consider the software encoders, which take a long time to run but require a minimal investment. If you will regularly be encoding long sequences of video, the real-time hardware route is for you. And if you need absolutely top quality, such as in encoding Hollywood movies, you'll want to get a multiple-pass encoder (such as the FutureTel and Philips products), where the video is analyzed first, then encoded.
Origins of MPEG
Originally designed for putting video onto CD-ROMs, MPEG 1 was optimized for the 1.5 megabits per second (Mbps) bit rate of single-speed CD-ROM drives. Released in 1992, it has also been widely adopted for satellite television (DSS). MPEG 1 offers a maximum resolution of 352 by 240, which is commonly referred to as SIF (standard input format) resolution. It is limited to 30 frames per second (fps) and has no provision for handling interlace. The quality of MPEG 1 video is roughly equivalent to that of VHS tape.
ÿÿÿ<Picture>ÿÿ MPEG 2 is the format that has been adopted for DVD (digital video discs) and DVD-ROM video, and it will be built in to new digital TV sets. MPEG 2 is capable of handling high-definition TV signals (HDTV), with resolutions up to 1,920 by 1,080 (at 30fps). It incorporates special provisions for interlace and offers variable bit rates.
ÿÿÿ<Picture>ÿÿ With the announcement of C-Cube Microsystems' single-chip MPEG 2 codec, which both encodes and decodes, MPEG 2 encoding systems have become more affordable. Jonathan Cassell, analyst at Dataquest, predicts that by 1999 or 2000 the price of an MPEG 2 chip should come down into the $50 range, from around $1,000 for a set of 14 chips once needed to do the same job. "Up to now, there's been a small market [for MPEG 2] -- a few professionals and experts," Cassell says. "The new codec changes the whole equation from a few thousand units to a million in just a few years." While the biggest-volume market for MPEG 2 today is professional broadcast applications and satellite television compression, he says the consumer market for DVD-recordable players, digital TV, and videoconferencing devices will grow as prices shrink.
ÿÿÿ<Picture>ÿÿ For content developers, an MPEG 2 encoder system is the key to jumping on the MPEG 2 bandwagon. These encoders convert ordinary video, from a camcorder or videocassette recorder, into MPEG 2 files. Any content producer interested in delivering the best possible picture quality while using the highest possible data compression (in the ballpark of 50:1 to 100:1) should be interested in MPEG 2. Experts consider DVD movies (which use MPEG 2) superior to laserdiscs; while laserdisc's horizontal resolution is 425 lines, DVD goes up to 500 lines. Higher bit rates are the reason: DVD video averages 3.5Mbps, more than double the bit rate of MPEG 1. Some DVD recorders also permit variable bit rates, so there can be more bits per second during action-packed scenes and fewer during static moments.
ÿÿÿ<Picture>ÿÿ But DVD represents just one possible implementation of MPEG 2. At the rate of 6Mbps, MPEG 2 delivers quality that is the same as the best broadcast-quality digital videotape (the component D1 format), with 720 by 480 resolution (30fps). And MPEG 2 will also be used for consumer HDTV signals, although none of the encoders listed in the chart could handle resolutions higher than 720 by 576.
ÿÿÿ<Picture>ÿÿ MPEG 2 encoding is a necessity for anyone involved in DVD-ROM production, but the higher quality may also be suitable for CD-ROM applications where a fast drive -- 4X or higher -- can be counted on (a kiosk, for example). And MPEG 2 video is working its way into hard-disk-based presentations, intranet training videos, and high-bandwidth video-on-demand.
ÿÿÿ<Picture>ÿÿ Applications for MPEG encoders are not limited to those requiring higher quality, however. All MPEG 2 encoders also can encode at the lower MPEG 1 bit rates, and many encoders can create lower resolutions -- such as 160 by 120 -- that may be suitable for Internet video and videoconferencing. (MPEG 4, which has not yet been released, is expected to be optimized for such low-bit-rate applications. If you're wondering what happened to MPEG 3, it was slated for HDTV but abandoned when MPEG 2 proved flexible enough to incorporate the new TV system.) |
