Variable Bit Rate Audio Indexing for Fast Seek
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Solution Overview
Problem
Existing digital audio encoding formats with variable bit rates face challenges in achieving near-instantaneous seek times, as traditional methods of decoding audio files are inefficient and do not scale well with increasing file sizes, leading to prolonged seek times.
Innovation Solution
A system generates an index using a hash function to quickly locate specific positions within a variable bit rate audio file, allowing for fast seek times by associating audio signal positions with corresponding file locations, which can be stored separately or within the audio file, and regenerated as needed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the decoder decodes portions of the audio file starting from the beginning to reach the seek position, then the seek operation can be performed, but the seek time increases proportionally with increasing file sizes
Solution Approach 1:
The patent applies preliminary action by pre-computing and storing index information during the encoding phase. The index contains mappings between audio signal positions and corresponding file locations, allowing the decoder to directly jump to the seek position without decoding from the beginning. This pre-computed index structure enables O(1) or O(log n) seek time complexity instead of linear time.
Solution Approach 2:
The patent introduces an index structure as an intermediary between the audio file and the decoder. This index acts as a mediator that translates audio signal positions into file locations, eliminating the need for the decoder to sequentially process audio data to reach the seek position. The index structure includes position-location mappings that enable direct random access to any point in the audio file.
2Loss of time
If an index is generated to support arbitrary seeking, then seek times are reduced, but storage overhead increases
Solution Approach 1:
The patent applies segmentation by dividing the index into multiple buckets, where each bucket contains a subset of position-location mappings. This segmentation allows the index to be stored and processed in smaller, more manageable units. The buckets can be distributed across storage or loaded selectively into memory, reducing the peak storage overhead and memory requirements while maintaining fast seek performance through hash-based bucket identification.
3Reliability
If the index is generated during the encoding process, then the index is available for seeking, but the encoding duration increases
Solution Approach 1:
The patent applies preliminary action by generating the index structure during the encoding process itself, rather than as a separate post-processing step. As audio frames are encoded, the encoder simultaneously computes and stores the corresponding position-location mappings in the index. This concurrent generation ensures the index is available immediately after encoding completes, enabling seeking functionality without requiring additional encoding passes or post-processing time.
Data Source
AI summary
Methods, systems, and apparatus, including computer programs encoded on computer storage media, for index variable bit stream audio files. One of the methods includes repeatedly receiving audio frames of a variable bit rate representation of an audio signal, wherein the variable bit rate representation comprises multiple portions that each represent one or more audio samples of the audio signal, and wherein at least two of the multiple portions have different respective bit rates. For each received audio frame, a position within the audio signal corresponding to the audio frame is determined. A location within an audio file corresponding to the position is determined. A hash value is computed from the determined position. A particular bucket of a plurality of buckets is identified according to the computed hash value. An indexed pair comprising the determined position and the determined location is generated and stored in association with the particular bucket.