PCM Frame Footer Marking for PCM-DSD Audio Identification
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Solution Overview
Problem
Conventional methods for distinguishing between Pulse Code Modulation (PCM) and Direct Stream Digital (DSD) audio data in multi-purpose data lines result in bandwidth overhead and increased complexity, leading to inefficient data transmission and potential noise generation due to incorrect decoding.
Innovation Solution
The use of a footer stored in low-order bits of audio data frames to indicate whether the data is PCM or DSD, allowing for improved bandwidth utilization and reduced overhead, enabling differentiation between PCM and DSD data without additional control lines or headers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a header is added to mark DSD data in PCM frames, then the encoding type can be identified, but bandwidth is reduced due to overhead
Solution Approach 1:
Instead of adding a header to mark DSD data (conventional approach), the patent inverts the approach by using the absence of a footer marker to indicate DSD data and presence of footer marker to indicate PCM data. This inversion eliminates the need for additional header bytes, thereby preserving bandwidth while achieving the same encoding identification function.
Solution Approach 2:
The patent extracts the encoding identification function from the header portion and relocates it to the footer portion of the data frame. By taking out the marker from the beginning of the frame and placing it at the end, the system achieves encoding identification without consuming additional bandwidth at the critical data transmission portion.
2Measurement precision
If a separate control line is added to indicate data type, then encoding can be determined, but circuit complexity increases
Solution Approach 1:
The patent merges the data payload and encoding identification into a single data frame structure. The footer marker is integrated into the existing PCM data frame format, allowing encoding identification to be performed without requiring separate control lines or additional circuitry for format detection.
Solution Approach 2:
The data frame structure is designed to serve multiple functions: carrying audio data payload and simultaneously indicating the encoding type through the footer marker. This multi-functionality eliminates the need for separate control lines, reducing circuit complexity while maintaining accurate data format identification.
3Quantity of substance
If footer markers are added to PCM data frames, then bandwidth efficiency is improved, but processing complexity increases
Solution Approach 1:
The footer marker is designed to be self-identifying and self-explanatory, requiring minimal processing to interpret. The simple presence or absence of the marker, or its basic value, directly indicates the encoding type without requiring complex analysis or additional processing steps, thus maintaining low processing complexity while improving bandwidth efficiency.
Data Source
AI summary
An encoding for data in an audio data stream may be indicated in the data stream using a footer stored in low-order bits of data frames in the audio data stream. When the audio data stream may include either Pulse Code Modulation (PCM) or Direct Stream Digital (DSD) data, PCM data may be marked with a footer to indicate the encoding as PCM. The footer may be a fixed value, an alternating fixed value, a predetermined sequence of values, or a value computed based on the PCM data. Examples of computed values for the footer marker may include an error code, an error correction code (ECC), and a scrambled code.