Digital Audio Transmission Metadata for Seamless Format Switching
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Solution Overview
Problem
In next-generation television broadcasting, switching between MPEG-4 AAC and MPEG-4 ALS audio formats causes audio reproduction issues due to changes in transmission rate and compression format, leading to potential allophe and sound omission, as existing methods lack effective mechanisms for seamless format switching and PLL relocking.
Innovation Solution
A transmission device and reception device system that adds metadata associated with the next digital audio signal to the currently transmitted signal, including transmission frequency, data type, sampling frequency, and encryption mode, allowing for synchronized processing and preparation for format changes, enabling smooth switching between different LPCM and compression digital audio signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the transmission format is switched from MPEG-4 AAC to MPEG-4 ALS, then the audio compression efficiency is improved, but the transmission rate changes from 48 kHz to 96 kHz causing PLL relocking delay and audio reproduction issues
Solution Approach 1:
The transmission device adds metadata indicating the next audio signal's format information (compression format and sampling frequency) to the current audio signal. This allows the reception device to prepare for format switching in advance by notifying the decoder of upcoming changes, enabling seamless transitions without PLL relocking delays or audio head omissions.
2Manufacturing precision
If the compression format is changed from AAC to ALS, then the audio quality is improved, but the decoder switching time increases causing audio head omission
Solution Approach 1:
The transmission device embeds metadata containing the next audio signal's compression format information in the current signal. The reception device's audio decoder uses this advance notification to prepare for format switching before it occurs, eliminating decoder switching delays and preventing audio head omissions while maintaining high audio quality.
3Device complexity
If no format notification mechanism is implemented, then the transmission system is simple, but the switching between different audio formats causes audio reproduction issues
Solution Approach 1:
The patent introduces metadata as an intermediary information carrier that conveys format transition notifications between the transmission and reception devices. This metadata is embedded within the existing audio bitstream and contains essential format information, enabling reliable format switching without requiring complex separate communication channels or control systems.
Data Source
AI summary
A plurality of kinds of LPCM signals/compression digital audio signals is switched to one another in transmission, thereby enabling audio reproduction to be satisfactorily carried out. A digital audio signal is transmitted to an external apparatus through a predetermined transmission path. Information associated with the digital audio signal to be next transmitted is added to the digital audio signal which is currently being transmitted. For example, first metadata exhibiting a transmission frequency of the digital audio signal, and second metadata exhibiting a data type of the digital audio signal are contained in the information.