# Audio sample rate for a sample entry ## Overview - Containing profile atom: Track (sound), movie - `part-ID`: `0x20202020` (universal feature) - `feature-code`: `'ausr'` - `feature-value`: Unsigned `int(32)` holding the audio sample rate in units per second (for example, `44100` for 44.1 kHz) ## Feature Values This feature value is an unsigned 32-bit integer holding the audio sample rate in units per seconds (cycles per second). The value should be rounded up to the nearest integer if it has a fractional portion. Examples: 24 kHz = `24000`, 44.1 kHz = `44100`. ## Writer Responsibilities A writer of the Audio Sample Rate feature should record the integer portion (rounded up if there is a fractional portion) of the audio sample rate found in a sound track’s `SoundDescription` structure. If multiple audio sample rates are used in the movie, then either all must recorded in the profile atom, or none must be recorded. ## Feature Value Algorithm This is the integer portion of the sample rate from a QuickTime audio sample description (rounded up if there is a fractional portion). If the sample rate is greater than 64 kHz, the integer portion can be recorded here. If a sample rate has a fractional portion, the writer should round up to the nearest integer. So, the `22254.54545` value that may occur in QuickTime audio as a Fixed value represented as `0x56EE8BA3` can be recorded as `22255`. ## Reader Responsibilities A reader of this feature code should compare the recorded value with its own audio sample rate limits. If the reader only supports discrete values (such as `44100`), it can perform equality comparisons (`=`). If the reader supports ranges of audio sample rates (such as all rates less than or equal to `32000`), the reader can perform relative comparisons (`<`, `<=`, `>`, or `>=`). --- Copyright © 2026 Apple Inc. All rights reserved. | [Terms of Use](https://www.apple.com/legal/internet-services/terms/site.html) | [Privacy Policy](https://www.apple.com/privacy/privacy-policy)