Transcoding Apparatus Using Decoded Picture Re-encoding
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Solution Overview
Problem
Existing video coding technologies face challenges in maintaining high processing efficiency and picture quality during multiple transcoding processes, particularly in adaptive streaming technologies like MPEG-DASH, where generating multiple bitrates increases costs and reduces coding efficiency and picture quality.
Innovation Solution
A transcoding apparatus and method that decodes a first bitstream and re-encodes it to generate multiple bitstreams with lower bitrates, using a multi-output re-encoding device with separate or combined re-encoders to minimize picture quality deterioration and coding efficiency loss by leveraging decoded pictures and stream basic information conversion processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If video coding data items of a plurality of bit rates are prepared for adaptive streaming, then users can select optimal bit rate according to viewing environment, but cost required to generate multiple video coding data items increases
Solution Approach 1:
The patent segments the video coding process into two distinct stages: (1) initial encoding of the original video data at high quality, and (2) subsequent transcoding of the already-encoded bitstream to generate multiple bit rate versions. This segmentation allows the expensive initial encoding to be performed only once, while the cheaper transcoding process generates all the required bit rate variants, thereby reducing overall manufacturing cost while maintaining adaptability.
Solution Approach 2:
The patent performs preliminary encoding of the video data at high quality before the adaptive streaming process begins. By pre-processing the video data into a high-quality bitstream format, the system eliminates the need to perform expensive encoding operations multiple times when generating different bit rate versions. This preliminary action stores the computational work in the form of encoded bitstream data that can be efficiently reused.
2Ease of manufacture
If transcoding is performed multiple times to generate video coding data items of a plurality of bit rates, then cost to generate multiple bit rates is reduced, but picture quality is reduced
Solution Approach 1:
The patent introduces a high-quality encoded bitstream as an intermediary between the original video data and the multiple bit rate output streams. Instead of directly transcoding original video data multiple times (which would accumulate quality loss), the system first creates a high-quality intermediate bitstream representation, then uses this intermediary to generate all lower bit rate versions. This intermediary preserves the maximum possible quality information for subsequent transcoding operations.
Solution Approach 2:
The patent creates a high-quality copy of the video data in the form of an encoded bitstream, which serves as the source for generating multiple bit rate versions. Rather than repeatedly copying and re-encoding the original video data (which would compound quality degradation), the system copies the video information into a compressed bitstream format that can be efficiently replicated and transcoded with minimal additional quality loss.
3Productivity
If decoded picture is used as input picture for transcoding, then processing amount is reduced, but picture quality is reduced when re-encoding is repeatedly performed
Solution Approach 1:
The patent maintains continuity of useful action by using the decoded picture from the high-quality bitstream as the input for all subsequent transcoding operations. Instead of periodically returning to the original video data or re-decoding different versions, the system continuously references the single high-quality decoded picture representation. This continuous reference to the same high-quality source ensures that all transcoded versions benefit from the same quality baseline while minimizing redundant processing.
Data Source
AI summary
In a transcoding apparatus structured to transcode one bitstream to a plurality of bitstreams, a decoder decodes a first bitstream and outputs a first decoded picture. A first re-encoder re-encodes the first decoded picture on the basis of the first bitstream to generate a second bitstream having a smaller bit rate than the first bitstream.