PCM Audio Frame Crossfading via Overlap and Fade
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Editing digital audio signals often results in audible artifacts such as spectral splatter, clicks, or thumps due to discontinuities at frame boundaries, making it difficult to seamlessly splice or edit audio information without introducing unwanted noise.
Innovation Solution
The method involves appending a replica of the preceding or following frame's audio segment to the beginning or end of audio frames, followed by fading techniques to smooth transitions, and overlapping these segments to create a crossfaded portion, which helps in maintaining the audio signal's continuity and reducing artifacts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If digital audio is packaged in frames or blocks that must be processed together, then transmission and storage efficiency is improved, but editing becomes difficult without creating audible artifacts
Solution Approach 1:
The patent applies preliminary action by pre-appending samples from one frame to the beginning of the next frame before transmission or storage. This preparation ensures that when editing occurs at frame boundaries, the necessary audio samples are already available to maintain continuity, eliminating the need for complex real-time processing during editing operations.
Solution Approach 2:
The patent segments the audio data by dividing it into frames with appended samples at the boundaries. Each frame contains not only its own audio samples but also appended samples from adjacent frames, creating self-contained segments that can be independently processed, transmitted, stored, and edited without affecting other segments.
2Ease of operation
If audio is edited at frame boundaries, then editing operations become simpler, but spectral splatter and audible artifacts occur
Solution Approach 1:
The patent prepares the audio data in advance by appending samples from one frame to the beginning of the next frame. This preliminary action ensures that when editing occurs at frame boundaries, the necessary audio samples are already available to maintain continuity, preventing spectral splatter and audible artifacts without complicating the editing process.
Solution Approach 2:
The appended samples act as a cushion or buffer at frame boundaries. When editing occurs, these pre-positioned samples provide a smooth transition that prevents abrupt discontinuities, thereby preventing spectral splatter and audible artifacts while maintaining editing simplicity.
3Productivity
If frame length is fixed for a given application, then processing becomes more efficient, but adaptability to different frame rates is reduced
Solution Approach 1:
The patent segments audio data into fixed-length frames with appended samples, where each frame is self-contained. This segmentation allows the system to process frames at a fixed rate for efficiency while the appended samples provide the flexibility needed to adapt to different frame rates and editing requirements without compromising processing efficiency.
Data Source
AI summary
Methods for splicing PCM audio frames form modified frames by appending to each frame either a portion of the next preceding frame or the next following frame. According to a first approach, splices are obtained by fading up and fading down a frame end and a frame appendage only at a splice point, and overlapping and combining to provide a crossfade at the splice. Alternatively, every frame end and frame appendage is faded up and faded down, overlapped and combined. A subtractive method of providing complementary fade-up and fade-down reduces rounding errors.