Video Transcoder Error-Adaptive Single and Multiple Descriptions
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Solution Overview
Problem
Conventional video transcoding methods, such as spatial and temporal localization, fail to effectively reduce error propagation in error-prone channel environments, leading to quality degradation of transmitted video data.
Innovation Solution
A video transcoder that includes a decoding unit, a single description/multiple description determining unit, and a transcoding unit, which determines whether to transcode into a single description or multiple descriptions based on error possibilities in the transmission channel, using a Lagrange cost comparison to decide between coding the DCT coefficient with the video header and motion vector, and dividing the DCT coefficient into multiple parts for error-adaptive transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional spatial localization method is used to limit error propagation by adding sync markers, then error propagation is reduced to smaller areas, but video quality degradation still occurs in error-prone channels
Solution Approach 1:
The patent divides the video data into multiple descriptions (first description and second description) with different levels of detail. The first description contains essential information for basic video reconstruction, while the second description contains additional information for enhanced quality. This segmentation allows the system to transmit multiple streams that can be independently received and combined, effectively segmenting the error impact so that errors in one description do not propagate to the other descriptions.
Solution Approach 2:
The patent changes the parameter of data representation by encoding the same video information in multiple different formats or levels of detail. By transforming the single video stream into multiple descriptions with varying levels of compression and detail, the system adapts the transmission parameters to match channel conditions, improving both error resilience and video quality.
2Reliability
If conventional temporal localization method is used to change inter macroblock to intra macroblock, then temporal error propagation is prevented, but compression efficiency is reduced
Solution Approach 1:
The patent segments the video data into multiple descriptions where the first description uses intra-macroblock encoding for error resilience while the second description uses inter-macroblock encoding for compression efficiency. This allows different parts of the video data to use different encoding strategies simultaneously, maintaining both error resistance and compression performance.
Solution Approach 2:
The patent dynamically selects which description to use or combine based on channel conditions. When the channel is error-prone, the system emphasizes the first description with intra-macroblock encoding. When the channel is reliable, the system can use the second description with inter-macroblock encoding for better compression. This dynamic adaptation resolves the contradiction between error control and compression efficiency.
3Adaptability or versatility
If multiple descriptions are transmitted to improve error adaptability, then error-adaptive transmission is achieved, but transmission complexity increases
Solution Approach 1:
The patent segments the transcoding process into distinct modules: a first transcoder that generates the first description with intra-macroblock encoding, and a second transcoder that generates the second description with inter-macroblock encoding. This modular segmentation allows each transcoder to be optimized independently, reducing the overall complexity compared to a single complex transcoder that must handle both encoding types simultaneously.
Data Source
AI summary
Provided is an apparatus for and a method of transcoding video, in which, in the transmission of a compressed video, the compressed video is transcoded into multiple descriptions in an error prone environment and is transcoded into a single description in an lower error or errorless environment. Video transcoder includes a decoding unit, a single description/multiple description determining unit, and a transcoding unit. The decoding unit decodes a compressed video to generate video header, a motion vector, and a DCT (discrete cosine transform) coefficient for each frame. The single description/multiple description determining unit determines whether to perform transcoding into a single description or multiple descriptions based on the possibility of errors occurring in a transmission channel of the compressed video. The transcoding unit performs transcoding into the single description by coding the DCT coefficient together with the video header and the motion vector when the single description/multiple description determining unit determines to perform transcoding into the single description and performs transcoding into the multiple descriptions by dividing the DCT coefficient into a plurality of DCT coefficients and coding each of the DCT coefficients together with the video header and the motion vector when the single description/multiple description determining unit determines to perform transcoding into the multiple descriptions.