Special-Frame Audio Decoding for Immediate 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 flexibility in adapting to variable bitrate conditions, especially in wireless communication environments.
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
1Device complexity
If a decoder is initialized without pre-roll frames, then the device complexity is reduced, but the decoder cannot properly decode audio data when switching between different codec configurations
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 before the current frame. These pre-roll frames are decoded first to initialize the decoder's internal state (such as filter states and buffer positions) so that when the current frame is decoded, the decoder is already in the correct configuration state. This preliminary initialization action ensures reliable decoding when switching between codec configurations without requiring complex external initialization procedures.
2Adaptability or versatility
If special frames with pre-roll frames are implemented, then immediate playback and seamless switching between codec configurations is enabled, but the bit stream size increases
Solution Approach 1:
The patent merges the special frame structure by integrating pre-roll frames, codec configuration information, and the current frame into a single unified frame format. Instead of transmitting separate initialization data and separate audio frames, all necessary components for decoder initialization and audio decoding are combined within the special frame itself. This merging reduces overhead compared to separate transmission mechanisms while enabling immediate playback and seamless codec configuration switching.
3Speed
If the decoder processes frames in real-time without pre-initialization, then the processing speed is maintained, but switching between codec configurations causes glitches and audio quality degradation
Solution Approach 1:
The patent performs preliminary decoding of pre-roll frames contained within the special frame structure before decoding the current frame. This preliminary action initializes the decoder's internal processing state (filter banks, buffer positions, prediction coefficients) in advance, ensuring that when the current frame is processed in real-time, the decoder is already configured correctly. This eliminates glitches and audio quality degradation during codec configuration switching while maintaining real-time processing speed for the actual audio output.
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.