Audio Tagging via Frequency Domain Bandpass Filtering
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Solution Overview
Problem
Existing audio tagging methods face limitations in identifying radio or television stations when multiple stations broadcast the same program, and they cannot accurately determine the distribution platform or ensure inaudible tagging without degrading the audio signal.
Innovation Solution
An audio tagging method that inserts an identification code into the audio signal by amplifying or attenuating specific frequency intervals associated with each bit of the code, using bandpass filters to minimize audible effects, allowing recognition through standard sound matching techniques.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an identification code is inserted into the audio signal using traditional methods, then the audio source can be identified, but the audio signal is degraded with unwanted audible signals or hissing
Solution Approach 1:
The patent changes the parameters of the audio signal by selectively amplifying or attenuating specific frequency intervals associated with each bit of the identification code. This modifies the frequency domain characteristics of the audio signal to embed the identification code without adding external signals that would cause audible degradation.
Solution Approach 2:
The patent transitions from time-domain signal processing to frequency-domain processing by applying bandpass filters centered on specific frequency intervals. This dimensional change allows the identification code to be embedded in the frequency spectrum rather than as temporal modifications, avoiding audible artifacts.
2Productivity
If sound matching techniques are used to identify audio sources, then listening data can be collected, but accurate identification is not possible when multiple stations broadcast the same program
Solution Approach 1:
The patent applies preliminary action by inserting the identification code into the audio signal at the source before broadcasting. This allows receiving devices to quickly identify the audio source through code recognition rather than having to analyze the entire audio content, significantly improving identification speed and accuracy even when multiple stations broadcast identical content.
3Reliability
If the audio signal is modified to include an identification code, then the code can be recognized, but the modification may become audible to the human ear
Solution Approach 1:
The patent carefully selects and modifies specific frequency intervals in the audio spectrum, changing parameters such as amplification or attenuation by specific decibel values. These parameter changes are designed to be sufficient for code recognition by processing devices while remaining below the threshold of human auditory perception.
Solution Approach 2:
The patent applies local quality by modifying only specific frequency intervals associated with each bit of the identification code, rather than uniformly modifying the entire audio spectrum. This localized modification approach ensures that changes are minimal and concentrated in specific frequency regions, making them less likely to be perceived by the human ear while still providing sufficient signal variation for accurate code recognition.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The method ensures accurate identification of audio sources without degrading the signal, maintaining inaudibility to the human ear and compatibility with existing sound matching systems, while enabling reliable listening data collection for radio and television stations.
Implementation Method 1
applying a bandpass filter centered on each of the frequency intervals associated with the bits of the code, such that: if the bit has the value 1, the value of the corresponding frequency interval is amplified; if the bit has the value 0, the value of the corresponding frequency interval is attenuated
Data Source
Figure 1
Figure 2~3
AI summary
An audio tagging method adapted to insert, in audio generated by an audio source and represented in the frequency domain, an identification code (21) which comprises a predefined number of bits, associating with each bit of the code a corresponding frequency interval (F(i)) and applying a bandpass filter centered on each of the frequency intervals associated with one of the bits of the code (21), such that: if the bit has the value 1, the value of the corresponding frequency interval is amplified; if the bit has the value 0, the value of the corresponding frequency interval is attenuated.