---
title: Audio priming-handling encoder delay in AAC
framework: quicktime-file-format
role: collectionGroup
path: quicktime-file-format/appendix_g_audio_priming_handling_encoder_delay_in_aac
---

# Audio priming-handling encoder delay in AAC

Position a source audio signal in a sound track to handle encoder delay.

## Overview

Overview This section describes temporal positioning of a source audio signal after AAC encoding into a sound track for QuickTime media files. The mechanisms described here are specified in ISO MPEG-4 standards (ISO/IEC 14496-12, 2008) and are used here with additional constraints. note: AAC implementations typically represent 1024 PCM audio samples in one AAC packet (synonymous in this context with a QuickTime media sample, and also referred to in ISO documents as an “access unit”). The terms “sample” and “audio sample” in this appendix are used to refer to PCM samples. For the encoded audio data, the terms “AAC packet” and QuickTime “media sample” are used.

## Topics

### Handling encoder delay

- [AAC encoding background](quicktime-file-format/background_aac_encoding.md)
- [The timing and synchronization problem](quicktime-file-format/the_timing_and_synchronization_problem.md)
- [Historical solution for implicit encoder delay](quicktime-file-format/historical_solution_implicit_encoder_delay.md)
- [Using track structures to represent encoder delay explicitly](quicktime-file-format/using_track_structures_to_represent_encode_delay_explictly.md)
- [Representing encoder delay explicitly](quicktime-file-format/example_representing_encoder_delay_explicitly.md)
- [Representing encoder delay with track structures](quicktime-file-format/summary_using_track_structures_to_represent_encoder_delay.md)

## See Also

### Storing audio data

- [Sound sample descriptions](quicktime-file-format/sound_sample_descriptions.md)
- [Sound sample description extensions](quicktime-file-format/sound_sample_description_extensions.md)
- [Sound sample data](quicktime-file-format/sound_sample_data.md)