# DASH manifest options in AWS Elemental MediaPackage
<a name="dash-trtmts"></a>

This section describes the options that AWS Elemental MediaPackage offers for modifying live output DASH manifests.

These options don't apply to video on demand (VOD) outputs or harvested live-to-VOD assets.

**Default DASH manifest**  
The following is a truncated example of a DASH manifest with no treatments:

```
<MPD>
  <Period>
    <AdaptationSet>
      <Representation>
        <SegmentTemplate>
          <SegmentTimeline>
            <S />
          </SegmentTimeline>
        </SegmentTemplate>
      </Representation>
    </AdaptationSet>
    .
    .
  </Period>
</MPD>
```

The elements of the DASH manifest are nested within the `MPD` (media presentation description) object. These are the elements of the manifest:
+ `Period` - The entire manifest is nested in one period.
+ `AdaptationSet` - Groups together representations of the same type (video, audio, or captions). There are one or more `AdaptationSets` in the `Period`.
+ `Representation` - Describes an audio, video, or captions track. There are one or more `Representations` in each `AdaptationSet`. Each representation is a track.
+ `SegmentTemplate` - Defines properties of the representation, such as the timescale and access URLs for media and initialization segments. There is one `SegmentTemplate` for each `Representation`.
+ `SegmentTimeline` - Describes when each segment is available for playback. There is one `SegmentTimeline` for each `SegmentTemplate`.
+ `S` - Describes when the segment is available (`t` value), the duration of the segment (`d` value), and a count of how many additional consecutive segments have this same duration (`r` value). There are one or more segments in the `SegmentTimeline`. 

MediaPackage can modify how some of these elements are presented in the output manifest. You can use the following treatment options on the output live manifest:
+ Separate the manifest into multiple periods, to allow ad breaks. See [DASH manifest options in AWS Elemental MediaPackageMulti-period DASH in AWS Elemental MediaPackage](multi-period.md).
+ Reduce the length of the manifest to make processing and playback more efficient. See [Compacted DASH manifests](compacted.md).
+ Control what segment information is used in the media URL in the `SegmentTemplate` properties. See [DASH manifest segment template format](segtemp-format.md).