Audio Frame Truncation Packets for Fine-Grained Stream Splicing
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Solution Overview
Problem
Existing audio splicing technologies are limited by the inability to address audio data at a fine temporal granularity, especially in stream formats like MPEG-2 transport streams, and truncation information in codecs like AAC is deeply embedded and difficult to modify on the fly.
Innovation Solution
The introduction of truncation unit packets in audio data streams to indicate end portions of audio frames for discard during playback, allowing precise splicing without additional data insertion and maintaining bitrate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If edit lists or extension_payload are used to indicate truncation information, then audio splicing capability is provided, but the truncation information is deeply embedded in the file format or access unit and cannot be easily modified on the fly by stream splicing devices
Solution Approach 1:
The patent extracts truncation information from the deeply embedded edit lists or extension_payload structures and places it into a separate, dedicated truncation indicator field in the syntax. This allows the truncation information to be easily accessible and modifiable by stream splicing devices without affecting the core audio encoding structure, thereby improving ease of operation while maintaining compatibility with existing formats.
Solution Approach 2:
The patent segments the audio data stream into access units with associated truncation indicators, allowing independent control of truncation information for each access unit. This segmentation enables stream splicing devices to modify truncation settings on a per-access-unit basis without impacting other parts of the stream, resolving the contradiction between ease of modification and structural complexity.
2Measurement precision
If audio data is addressed in granularity of coded chunks (access units), then transport and decoding are simplified, but the ability to address audio data at finer temporal granularity is lost
Solution Approach 1:
The patent introduces truncation indicators at the access unit level that specify which portions of decoded audio samples should be discarded. This preliminary marking allows the decoding process to proceed at the coarser access unit granularity for efficiency, while still enabling precise temporal control by indicating exactly which samples within each access unit should be retained or discarded, thereby achieving fine temporal granularity without increasing structural complexity.
Solution Approach 2:
The patent applies local quality control by allowing different truncation settings for different access units within the same audio stream. Each access unit can have its own truncation indicator specifying the number of trailing samples to discard, enabling precise temporal granularity at local levels while maintaining the overall simplified access unit structure for transport and decoding.
3Productivity
If truncation information is deeply embedded in AAC access units, then audio decoding is simplified, but stream splicing operations become difficult to perform on the fly
Solution Approach 1:
The patent introduces an intermediary truncation indicator field that sits between the AAC access unit structure and the actual audio sample data. This intermediary structure provides a dedicated interface for stream splicing operations, allowing splicing devices to modify truncation settings without directly manipulating the deeply embedded AAC access unit structures or the audio sample data, thereby enabling fast on-the-fly splicing while preserving the simplified decoding path.
Data Source
AI summary
Audio splicing is rendered more effective by the use of one or more truncation unit packets inserted into the audio data stream so as to indicate to an audio decoder, for a predetermined access unit, an end portion of an audio frame with which the predetermined access unit is associated, as to be discarded in playout.