Export Validation Performance

[joelmacx]

Description

Improve performance of tools used to validate and playback IAMF files. Most notably we use a more clever indexing method instead of brute force counting. These gains carryover to asynchronous task execution.

Observed indexing go from 640ms to 8ms for a 30s IAMF file.

Changes

1. Update the IAMFFileReader indexing to calculate the size of the file based on TPU size after parsing descriptor OBUs.
2. Reduce the amount of audio buffered initially and after seeks. This generally decreases startup time and seek time.
3. Add some unit test coverage for this new indexing method.

Validation and Acceptance Criteria

• Updated unit test coverage.
• Documented this new indexing method.
• Validated performance gains in host.