Digital Fingerprinting via Audio Envelope Thresholds
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Solution Overview
Problem
Existing digital signature technologies face challenges in generating robust and consistent fingerprints for media content, particularly in the presence of distortions, and are costly and invasive, making them unsuitable for applications like audience measurement and digital copyright management.
Innovation Solution
The method involves generating digital fingerprints using a combination of time-domain and spectral analysis, with band pass filtering, waveform shaping, threshold determination, and fingerprint start point identification, to produce unique and robust signatures that are immune to distortions such as ambient noise and playback variations, allowing for accurate matching across different conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If directly monitoring tuning circuits in TV or radio sets is used, then channel information can be obtained, but physical entry into and modification of the device is required which is invasive
Solution Approach 1:
The patent uses embedded identification codes as an intermediary element that carries channel information without requiring direct access to tuning circuits. These codes are transmitted through the audio signal, allowing measurement of channel information indirectly through the audio carrier wave, thus eliminating the need for invasive modification of the TV or radio set.
2Ease of operation
If monitoring embedded identification codes is used, then channel information can be obtained without physical modification, but the codes must be reliably detectable in all programs which is not always possible
Solution Approach 1:
The patent makes the audio signal serve multiple functions: it carries both the program content and the embedded identification codes. By monitoring the audio signal components, the system can universally extract channel information from any broadcast program regardless of the specific content, ensuring reliable detection across all programs without requiring program-specific modifications.
3Ease of operation
If deriving signatures from program signals at the point of viewing is used, then no physical modification is needed, but the process is demanding in terms of cost and hardware needed
Solution Approach 1:
The patent extracts the identification information from the audio signal by analyzing specific frequency components and temporal patterns. By taking out only the essential features (frequency content, duration, sequence) rather than processing the entire audio signal, the system reduces hardware and computational requirements while maintaining the ability to uniquely identify programs and channels.
4Measurement precision
If generating digital fingerprints from audio samples is used, then media identification can be performed, but the fingerprints are susceptible to inconsistencies due to different reception conditions and equipment capabilities
Solution Approach 1:
The patent transforms the audio signal into the frequency domain using Fast Fourier Transform (FFT), changing the representation parameters from time-domain amplitude to frequency-domain spectral content. This parameter transformation makes the fingerprints robust to distortions because frequency characteristics are more stable across different reception conditions, equipment capabilities, and audio processing operations than time-domain parameters.
Data Source
AI summary
Digital signature generation apparatus, comprising an envelope generator operable to generate an envelope representation, of only one polarity, of a sampled data segment, and operable for each of successive portions comprising a predetermined plurality of samples to provide a portion sum value as the sum the values of the samples in the portion, thereby to provide said envelope representation; a threshold value generator operable to determine a threshold value for each portion of the envelope representation; an event detector operable to detect, as an event, a transition of a portion sum value across the threshold value for the portion concerned; and a signature generator operable in response a detected event to generate a digital signature characteristic of the sampled data segment.