Compressed Audio Cross-Fading via Packet Processing
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Solution Overview
Problem
Existing digital media delivery systems lack the capability to perform cross-fading and other effects between media elements on downstream devices, resulting in a less satisfactory user experience due to the absence of upstream processing and the limitations of consumer devices in simultaneous decode and presentation of media elements.
Innovation Solution
Implementing systems and methods for efficient cross-fading and processing of compressed bitstreams directly on user devices, allowing for cross-fading between different compression formats by creating composite compressed packets that can be decoded with a single hardware decoder, using packet time alignment and synthesized packet generation to achieve time-aligned and weighted packet pairs for seamless playback.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If cross-fading is performed by fully decoding both compressed streams to PCM and then mixing, then cross-fade quality is improved, but decoding time and computational complexity increase significantly
Solution Approach 1:
The patent segments the audio stream into individual packets and processes only the necessary packets for cross-fading. Instead of fully decoding entire streams, it identifies and processes specific packet pairs that need to be cross-faded, significantly reducing the amount of data that requires full decoding while maintaining cross-fade quality.
Solution Approach 2:
The patent changes the processing dimension by performing cross-fading operations in the compressed packet domain rather than in the fully decoded PCM time domain. This dimensional shift allows cross-fade operations to be performed on compressed data structures, reducing computational complexity and decoding time while preserving audio quality.
2Adaptability or versatility
If two separate hardware decoders are used to enable simultaneous decoding of two streams for cross-fading, then cross-fade capability is improved, but device complexity and cost increase
Solution Approach 1:
The patent merges the decoding and cross-fading operations into a single processing pipeline. By combining these functions, the system can perform cross-fading between two streams using a single hardware decoder, eliminating the need for two separate decoders and reducing device complexity while maintaining cross-fade capability.
Solution Approach 2:
The patent creates a universal processing architecture where a single decoder can handle multiple stream decoding and cross-fading operations. This multi-functional approach allows one decoder to serve multiple purposes, reducing the overall number of components needed in the system.
3Adaptability or versatility
If software-based decoding is used to enable cross-fading on single-decoder devices, then cross-fade capability is improved, but battery consumption increases
Solution Approach 1:
The patent applies partial action by performing only the minimum necessary decoding and processing operations to enable cross-fading. Instead of fully decoding streams or using resource-intensive software-based decoding, it processes only the essential packet pairs in the compressed domain, significantly reducing computational load and battery consumption while maintaining cross-fade capability.
4Measurement precision
If precise synchronization of multiple decoders is implemented, then cross-fade accuracy is improved, but system complexity and difficulty of implementation increase
Solution Approach 1:
The patent performs preliminary actions by pre-synchronizing packet timing information during the decoding process. It uses packet timing data and sequence numbers to pre-align the compressed packets before cross-fading operations, ensuring accurate synchronization without requiring complex real-time coordination between multiple decoders.
Data Source
AI summary
Systems and methods are presented for efficient cross-fading (or other multiple clip processing) of compressed domain information streams on a user or client device, such as a telephone, tablet, computer or MP3 player, or any consumer device with audio playback. Exemplary implementation systems may provide cross-fade between AAC/Enhanced AAC Plus (EAACPlus) information streams or between MP3 information streams or even between information streams of unmatched formats (e.g. AAC to MP3 or MP3 to AAC). Furthermore, these systems are distinguished by the fact that cross-fade is directly applied to the compressed bitstreams so that a single decode operation may be performed on the resulting bitstream. Moreover, using the described methods, similar cross fade in the compressed domain between information streams utilizing other formats of compression, such as, for example, MP2, AC-3, PAC, etc. can also be advantageously implemented. Thus, in exemplary embodiments of the present invention a set of frames from each input stream associated with the time interval in which a cross fade is decoded, and combined and recoded with a cross fade or other effect now in the compressed bitstream. Once sent through the client device's decoder, the user hears the transitional effect. The only input data that is decoded and processed is that associated with the portion of each stream used in the crossfade, blend or other interstitial, and thus the vast majority of the input streams are left compressed.