QuickTime audio codec type

Overview

Containing profile atom: Track (sound), movie
part-ID: 0x20202020 (universal feature)
feature-code: 'afmt'
feature-value: Unsigned int(32) (a four-character-code) holding the QuickTime audio codec type copied from SoundDescription structure’s dataFormat field

Feature Values

This is the four-character-code found in a sound sample description.

Examples: 'mp4a', 'twos'.

Writer Responsibilities

A writer of the QuickTime audio codec type feature should record the four-character-code corresponding to the QuickTime audio format type or types also recorded in the sound track’s sample descriptions.

Feature Value Algorithm

The feature value is the audio codec type read from a SoundDescription structure’s dataFormat field. If there are multiple sample descriptions with different audio codec types, either all QuickTime Audio Codec Type features must be recorded in the profile atom or none must be recorded.

Reader Responsibilities

A reader of this feature code should compare the recorded value by an equality comparison (using =) with the format codes supported by the reader.