Thursday, October 15, 2009, 01:10 pm
Apple looks to improve visual quality of streaming videoApple has investigated a method to make imperfections in compressed video files less visible to the human eye, a new patent application revealed this week shows.
The described technology would not do away with compression, which is necessary given bandwidth restrictions. Instead, it details a new technology that would mask artifacting that often appears when video files are compressed to reduce their file size.
"Disadvantageously, most video compression standards use lossy data compression techniques in which data determined by a particular compression algorithm to be of lesser importance to the overall content, but which is nonetheless discernible and objectionable to the user, is discarded," the application reads. As a result, certain video compression algorithms may introduce visual artifacts into the decoded video stream, which may be distracting to a user when viewing the decoded video data."
It continues: "Such visual artifacts are generally attributable to the latent error in lossy data compression and may appear more frequently as higher video compression rates are used. Moreover, such artifacts are exacerbated when the decoded video images are scaled to larger high definition displays. "
Earlier this year, Apple was rumored to be working on a new service called iTunes Replay. It was said to allow users to stream iTunes video purchases directly from the company's servers for playback anywhere. Such a system would prevent the need for local storage to save large video files.
Apple has also taken interest in streaming video on the iPhone, with the latest 3.0 software allowing the HTTP Live Streaming standard. Apple has provided the QuickTime Streaming Server for the last decade, but that format has run into issues as it is often blocked by firewalls. But the new HTTP streaming technology allows simple real-time streaming of content and can offer multiple versions of clips in different formats which could automatically switch based on bandwidth availability.
The patent application describes a system that would introduce "random noise" into a video stream to reduce or mask the visibility of the effects of compression on video. The technology would analyze the video and determine appropriate places based on the picture's characteristics to insert the noise and mask the artifacting, otherwise known as "fuzziness" in an overly compressed image. Such a system could be used on a computer, an Apple TV, or an iPhone.
"(A device), upon receiving streaming compressed video data from a network connection via network (device), may decode the compressed video data and temporarily buffer or cache the decoded video data in the (memory)," the patent application states. "In one embodiment, the noise generation (system) may sequentially process each frame of the video data buffered in the (memory) on a pixel-by-pixel basis. Each buffered pixel is read from the (memory) via an input data (bus) coupled to the noise generation."
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