Crate dash_mpd

A Rust library for parsing, serializing and downloading media content from a DASH MPD manifest, as used for on-demand replay of TV content and video streaming services. Allows both parsing of a DASH manifest (XML format) to Rust structs (deserialization) and programmatic generation of an MPD manifest (serialization). The library also allows you to download media content from a streaming server. DASH (dynamic adaptive streaming over HTTP), also called MPEG-DASH, is a technology used for media streaming over the web, commonly used for video on demand (VOD) services. The Media Presentation Description (MPD) is a description of the resources (manifest or “playlist”) forming a streaming service, that a DASH client uses to determine which assets to request in order to perform adaptive streaming of the content. DASH MPD manifests can be used both with content encoded as MPEG and as WebM.

This library provides a serde-based parser (deserializer) and serializer for the DASH MPD format, as formally defined in ISO/IEC standard 23009-1:2022. This version of the standard is available for free online. XML schema files are available for no cost from ISO. When MPD files in practical use diverge from the formal standard, this library prefers to interoperate with existing practice.

The library does not yet provide full coverage of the fifth edition of the specification. All elements and attributes in common use are supported, however.

The library also provides experimental support for downloading content (audio or video) described by an MPD manifest. This involves selecting the alternative with the most appropriate encoding (in terms of bitrate, codec, etc.), fetching segments of the content using HTTP or HTTPS requests (this functionality depends on the reqwest crate) and muxing audio and video segments together (using ffmpeg via the ac_ffmpeg crate).

DASH features supported

• VOD (static) stream manifests
• Multi-period content
• XLink elements (only with actuate=onLoad semantics, resolve-to-zero supported)
• All forms of segment index info: SegmentBase@indexRange, SegmentTimeline, SegmentTemplate@duration, SegmentTemplate@index, SegmentList
• Media containers of types supported by mkvmerge, ffmpeg, VLC and MP4Box (this includes Matroska, ISO-BMFF / CMAF / MP4, WebM, MPEG-2 TS)
• Subtitles: preliminary support for WebVTT and TTML streams

Limitations / unsupported features

• Dynamic MPD manifests, that are used for live streaming/OTT TV
• XLink with actuate=onRequest semantics
• Application of MPD patches

Modules

fetch

Support for downloading content from DASH MPD media streams.

scte35

Support for the SCTE-35 standard for insertion of alternate content

sidx

Structs

Accessibility

Specifies the accessibility scheme used by the media content.

AdaptationSet

Contains a set of Representations.

AssetIdentifier

Identifies the asset to which a given Period belongs.

AudioChannelConfiguration

Specifies information concerning the audio channel (e.g. stereo, multichannel).

BaseURL

A URI string that specifies one or more common locations for Segments and other resources.

BitstreamSwitching

Information on the bitstream switching capabilities for Representations.

CencPssh

A Common Encryption “Protection System Specific Header” box. Content is typically base64 encoded.

ContentComponent

Describes a media content component.

ContentProtection

Contains information on DRM (rights management / encryption) mechanisms used in the stream.

Copyright

Copyright information concerning the media stream.

EssentialProperty

Event

A mechanism allowing the server to send additional information to the DASH client which is synchronized with the media stream.

EventStream

FailoverContent

Period of time for which either failover content or no content/segments exist for the parent Representation.

Fcs

Failover Content Segment (FCS).

FramePacking

Specifies frame-packing arrangement information of the video media component type.

InbandEventStream

“Inband” events are materialized by the presence of DASHEventMessageBoxes (emsg) in the media segments.

Initialization

The first media segment in a sequence of Segments.

Label

Provides a textual description of the content, which can be used by the client to allow selection of the desired media stream.

Language

Latency

Laurl

Licence acquisition URL for content using Microsoft PlayReady DRM.

LeapSecondInformation

Location

A URI string to which a new request for an updated manifest should be made.

MPD

The root node of a parsed DASH MPD manifest.

Metrics

MsprIVSize

MsprIsEncrypted

MsprKid

MsprPro

Initialization data that is specific to the Microsoft PlayReady DRM.

OutputProtection

PatchLocation

The Patch mechanism allows the DASH client to retrieve a set of instructions for replacing certain parts of the MPD manifest with updated information.

Period

Describes a chunk of the content with a start time and a duration. Content can be split up into multiple periods (such as chapters, advertising segments).

PlaybackRate

Preselection

A Preselection is a personalization option to produce a “complete audio experience”.

ProducerReferenceTime

Specifies wall‐clock times at which media fragments were produced.

ProgramInformation

Metainformation concerning the media stream (title, language, etc.)

Range

Rating

Specifies that content is suitable for presentation to audiences for which that rating is known to be appropriate, or for unrestricted audiences.

Reporting

Representation

A Representation describes a version of the content, using a specific encoding and bitrate.

RepresentationIndex

Resync

Role

The Role specifies the purpose of this media stream (caption, subtitle, main content, etc.).

S

Describes a sequence of contiguous Segments with identical duration.

Scope

Scope of a namespace.

Scte214ContentIdentifier

DASH specification MPEG extension (SCTE 214) program identification type.

SegmentBase

Specifies some common information concerning media segments.

SegmentList

Contains a sequence of SegmentURL elements.

SegmentTemplate

Allows template-based SegmentURL construction. Specifies various substitution rules using dynamic values such as $Time$ and $Number$ that map to a sequence of Segments.

SegmentTimeline

Contains a sequence of S elements, each of which describes a sequence of contiguous segments of identical duration.

SegmentURL

The URL of a media segment.

Selection

SelectionInfo

ServiceDescription

Source

The original source of the media stream.

SubRepresentation

A SubRepresentation contains information that only applies to one media stream in a Representation.

Subset

Subsets provide a mechanism to restrict the combination of active Adaptation Sets.

SupplementalProperty

Switching

Information used to allow Adaptation Set Switching (for instance, allowing the player to switch between camera angles).

Title

The title of the media stream.

UTCTiming

Used to synchronize the clocks of the DASH client and server, to allow low-latency streaming.

Viewpoint

Enums

DashMpdError

SubtitleType

Functions

check_conformity

Returns a list of DASH conformity errors in the DASH manifest mpd.

is_audio_adaptation

Returns true if this AdaptationSet contains audio content.

is_subtitle_adaptation

Returns true if this AdaptationSet contains subtitle content.

is_video_adaptation

Returns true if this AdaptationSet contains video content.

parse

Parse an MPD manifest, provided as an XML string, returning an MPD node.

subtitle_type

Type Aliases

XsDatetime

Type representing an xs:dateTime, as per https://www.w3.org/TR/xmlschema-2/#dateTime