Channel-Based Audio to Object-Based Conversion via Metadata Reordering
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Solution Overview
Problem
Channel-based audio (CBA) coding struggles to adapt to varying speaker setups, leading to compatibility issues when the source speaker layout does not match the playback speaker layout, which is a challenge in authoring content that plays back well independently of the speaker configuration.
Innovation Solution
The method involves converting CBA content to object-based audio (OBA) content by parsing signaling parameters from the CBA metadata to determine appropriate OAMD representations, generating channel shuffle information, reordering audio channels, and rendering or encoding the audio using OAMD to ensure compatibility with OBA playback devices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If channel-based audio coding is used with predetermined channel configuration, then compatibility with existing devices is improved, but adaptability to varying speaker setups deteriorates
Solution Approach 1:
The patent introduces object-based audio as an intermediary format between channel-based audio sources and diverse speaker configurations. The system converts CBA to OBA using object audio metadata that describes spatial positions of audio objects, allowing flexible mapping to various speaker layouts without requiring predetermined configuration knowledge at the decoding end.
Solution Approach 2:
The patent changes the fundamental parameter representation from channel-based fixed mappings to object-based spatial coordinate systems. By representing audio in terms of object positions (x, y, z coordinates) rather than fixed channel assignments, the system can adapt to different speaker configurations by transforming the spatial parameters to match the target playback environment.
2Reliability
If standardized CBA formats are used, then device compatibility is improved, but flexibility in representing diverse speaker configurations deteriorates
Solution Approach 1:
The patent makes the audio system universal by creating a single object-based representation that can serve multiple speaker configurations simultaneously. The object audio metadata framework can represent any speaker layout by adjusting the spatial position parameters, eliminating the need for separate encoding schemes for different configurations while maintaining compatibility with existing standardized formats.
3Adaptability or versatility
If channel-based audio is used without assuming speaker layout, then adaptability to various setups is improved, but the ability to redistribute audio to available speakers deteriorates
Solution Approach 1:
The patent performs preliminary action by pre-defining the spatial positions of audio objects in the source material using object audio metadata. This preliminary spatial mapping allows the system to later redistribute the audio to any speaker configuration by simply transforming the pre-defined object positions to match the target speaker layout, making the redistribution process straightforward and automated.
Data Source
AI summary
Embodiments are disclosed for channel-based audio (CBA) (e.g., 22.2-ch audio) to object-based audio (OBA) conversion. The conversion includes converting CBA metadata to object audio metadata (OAMD) and reordering the CBA channels based on channel shuffle information derived in accordance with channel ordering constraints of the OAMD. The OBA with reordered channels is rendered in a playback device using the OAMD or in a source device, such as a set-top box or audio/video recorder. In an embodiment, the CBA metadata includes signaling that indicates a specific OAMD representation to be used in the conversion of the metadata. In an embodiment, pre-computed OAMD is transmitted in a native audio bitstream (e.g., AAC) for transmission (e.g., over HDMI) or for rendering in a source device. In an embodiment, pre-computed OAMD is transmitted in a transport layer bitstream (e.g., ISO BMFF, MPEG4 audio bitstream) to a playback device or source device.