Audio Decoder Special Frames for Instant Codec Switching
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Solution Overview
Problem
Existing audio encoding and decoding technologies face challenges in seamlessly switching between different codec configurations, leading to potential glitches and reduced audio quality due to decoder start-up delays and incompatible codec configurations, especially in environments with variable bitrates.
Innovation Solution
Incorporating a special frame with additional information that includes encoded audio sample values from preceding frames, using the same codec configuration, to initialize the decoder and facilitate immediate playback and seamless switching between codec configurations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a decoder is initialized normally without additional information, then the decoder structure is simple, but the decoder cannot immediately decode audio data upon start-up or switching, causing playback delays
Solution Approach 1:
The patent applies preliminary action by including pre-roll frames (encoded audio sample values from preceding frames) within the special frame structure. These pre-roll frames are prepared in advance and embedded in the bit stream, allowing the decoder to immediately initialize and decode audio data without waiting for external configuration or additional startup frames, thus achieving immediate playback upon start-up or switching
2Loss of time
If the decoder includes pre-roll frames for immediate playback, then the playback delay is reduced, but the bit stream size increases
Solution Approach 1:
The patent merges the pre-roll frames with the current frame by incorporating them as additional information within the special frame structure. Instead of transmitting separate pre-roll frames as independent data units, they are combined into the current frame's payload, allowing the decoder to access both the current frame data and the pre-roll frames in a single transmission unit, thus reducing overall bit stream volume while maintaining immediate playback capability
3Reliability
If the special frame includes encoded audio sample values from preceding frames, then the decoder can be initialized properly, but the frame structure becomes more complex
Solution Approach 1:
The patent introduces an intermediary element (the special frame structure with additional information fields) that mediates between the preceding frames and the current frame. This intermediary structure provides a standardized interface for incorporating pre-roll frames, allowing the decoder to reliably initialize by accessing the encoded audio sample values through a defined data structure, thus improving initialization reliability while managing complexity through structured organization
Data Source
AI summary
An audio decoder decodes a bit stream of encoded audio data, which bit stream represents a sequence of audio sample values and includes a plurality of frames, wherein each frame includes associated encoded audio sample values. The audio decoder includes a determiner configured to determine whether a frame of the encoded audio data is a special frame including encoded audio sample values associated with the special frame and additional information, wherein the additional information include encoded audio sample values of a number of frames preceding the special frame, wherein the encoded audio sample values of the preceding frames are encoded using the same codec configuration as the special frame, wherein the number of preceding frames is sufficient to initialize the decoder to be in a position to decode the audio sample values associated with the special frame if the special frame is the first frame upon start-up of the decoder.