Sony's new single chip encoder is aimed at BetaCam.
DVx motion estimation......................................
The new codec architecture contains a number of features specifically designed to improve video quality while maintaining a low data rate. First, an improved hierarchical ME algorithm has been implemented, the result of years of study directed at achieving a successful compromise between wide-range and fine-grained search. The algorithm implemented uses a horizontal search range of ñ201 pixels horizontally, and ñ124 pixels vertically. A horizontal range of greater than ñ201 pixels was considered, but after encoding and analyzing hundreds of video sequences it was rejected. Because the vast majority of video contains motion that falls well within these selected boundaries, it is preferable to spend additional processing cycles during the fine-grained search phase rather than extending the higher-level search over a broader area. In addition, it was discovered that fast motion (beyond the selected search ranges) tends to create extremely blurred video images, thereby resulting in unreliable motion estimation results.
Sony.........................................
The CXD1922Q uses an advanced adaptive motion estimation algorithm developed by Sony for efficient video compression processing. The chip offers a search range of minus 288 to plus 297.5 horizontal pixels and minus 96 to plus 95.5 vertical pixels, at half-pixel accuracy, allowing high-quality encoding of rapidly moving scenes and video taken with fast camera movements. The CXD1922Q also supports dual prime encoding for low bit-rate applications.
VisionTech......................................
The motion vector search range is
plus or minus 150 pixels horizontally and plus or minus 34 pixels vertically
DVx bit rates................................
As technology has progressed, new digital acquisition technologies are driving new standards such as DV, also known as DVC, a format that is now being adopted rapidly by the editing community. Using the DV format in editing eliminates the need for analog capture and JPEG compression devices. Two current formats for DV include DV consumer, which uses 4:1:1 chroma sampling and supports a 25 Mbps bit rate, and DV prosumer, which employs 4:2:2 chroma sampling and a 50 Mbps bit rate. Like M-JPEG, DV is significantly inferior to MPEG-2 in compression efficiency, but there are single-chip codec solutions that are suitable for cost-effective video editing stations.
Sony...............................
The Sony CXD1922Q supports MP at ML and SP at ML with image sizes up to 720x480 at 30fps for NTSC applications and up to 720x576 at 25fps for PAL applications. Full D1 resolution, single-pass encoding at 15Mpbs for I, P and B frames and 25Mbps for I frame is incorporated as well. The chip provides support for constant and variable bit rates, and automatic 3:2 pull-down inversion when required.
VisionTech......................................
The product encodes broadcast quality, full D1 images (NTSC 72Ox480 pixel
at 30 fps, or PAL, at 72Ox576 pixel at 25fps) in real time. The maximum speed
of data encoding is 24 Mbits per second
DVx power Consumption................................
Today's DVx codec, packed with 5.5 million transistors, is as big as the Pentium II, according to Saffari. In the encode mode, power dissipation is between 3.5 and 4 W. By moving to 0.25-micron and, later, to 0.18-micron process technologies as they become available, C-Cube plans "to optimize the memory utilization and reduce the power consumption to 1-to-2 W as a codec," Saffari said. "For camcorder design wins, it's necessary to bring it down to 1.2 to 0.7 W."
Sony....................................
The chip requires just 32Mbit of SDRAM and is rated at 1.2W for power consumption
VisionTech............................
The voltage is 33VDC, and power consumption is 6W.
Sony |
