Monday, September 20, 2010
Enhancing Video Quality – Not all Post Video Processing is the Same
The processing of video signals after it is decoded is critical to quality of high motion video (such as sports) in digital displays (LCD and LED displays). During the Set Top Box 2010 conference, Stuart McKechnie from Zoran explained to me that not all video post processing is the same. The need for post processing comes from the limited persistence (LEDs) and slow response time (LCDs) of digital displays that cause flicker when viewing content at low frame rates, such as 60 fps for TV or 24 fps for movies. Solving the flicker problem involves increasing the refresh rate of the display to 120 Hz or 240 Hz. However converting the content to these frame rates by simply duplicating frames causes an unpleasant juddering effect when objects are moving. The quality of the video display can be improved dramatically by creating new – interstitial - frames with FRC (Frame Rate Conversion) circuitry. The older approach to this - called MEMC (Motion Estimation Motion Compensation) – is effective for fairly simple scenes. However, MEMC has no intrinsic understanding of the structure of the image and increasingly introduces artifacts for faster and/or more complex motion. This is even worse for 3D Video where spatial errors in the interstitial frames translate into distance errors. The latest Object Based FRC technology pioneered by Zoran solves these problems by using an object model and assigning interpolated pixels according to the motion of the corresponding object.