---
title: Hint sample data format
framework: quicktime-file-format
role: symbol
role_heading: Atom
path: quicktime-file-format/hint_track_sample_description
---

# Hint sample data format

An atom that specifies the data format and location of the hint track sample data.

## Overview

Overview The sample description atom ('stsd') contains information about the hint track samples. It specifies the data format (note that currently only RTP data format is defined) and the data reference to use (if more than one is defined) to locate the hint track sample data. It also contains some general information about this hint track, such as the hint track version number, the maximum packet size allowed by this hint track, and the RTP time scale. It may contain additional information, such as the random offsets to add to the RTP time stamp and sequence number. The sample description atom can contain a table of sample descriptions to accommodate media that are encoded in multiple formats, but a hint track can be expected to have a single sample description at this time. The sample description for hint tracks is defined in the following table.  |   |   |   |   |   |   |   |   |

## Topics

### Data fields

- [Size](quicktime-file-format/hint_track_sample_description/size.md)
- [Data format](quicktime-file-format/hint_track_sample_description/data_format.md)
- [Reserved](quicktime-file-format/hint_track_sample_description/reserved.md)
- [Data reference index](quicktime-file-format/hint_track_sample_description/data_reference_index.md)
- [Hint track version](quicktime-file-format/hint_track_sample_description/hint_track_version.md)
- [Last compatible hint track version](quicktime-file-format/hint_track_sample_description/last_compatible_hint_track_version.md)
- [Max packet size](quicktime-file-format/hint_track_sample_description/max_packet_size.md)
- [Additional data table](quicktime-file-format/hint_track_sample_description/additional_data_table.md)

## See Also

### Hint media

- [Hint media](quicktime-file-format/hint_media.md)
- [Finding an original media track from a hint track](quicktime-file-format/finding_an_original_media_track_from_a_hint_track.md)
- [RTP hint tracks](quicktime-file-format/rtp_hint_tracks.md)
- [Packetization hint sample data](quicktime-file-format/packetization_hint_sample_data.md)