HNTF/Home Network TF Discussions/VideoTagSupportMpeg2-ts
From Web and TV IG
Tracker Issue ID: ISSUE-18
Description: The support of MPEG2-Transport Stream is fundamental to viewing content in the home (ex. TV). Applications require an API to have control and access of MPEG2-TS components.
This use case puts explicit requirements of what the the application may requires support from the video tag (HTML5). While video tag support many of the indicated implementation requirements not all are supported. This use case may not explicitly indicate the missing portions but highlights the full set of implementation requirements.
In order to have a basic overview of MPEG2-TS below is a diagram and defintion of what is in each type of component. The MPEG2-TS may carry one or more components of type video, audio and subtitles. Program is depicted in the diagram but not applicable for this use case. Each component type has a list of elements to be supported. The 3 types of components have a PID associated to it, encoding format and and an indication if encryption is active. There are unique elemements for each component type. The video component may also indicate aspect ratio. The audio component has a language indication (based on ISO 639), an audio description and an indication of number of audio channels. The subtitle component has a language indication (based on ISO 639) and an indication of hearing impaired.
Implementation: There shall be support in the video tag for an application to have the following control:
- An application shall retrieve a list of available components, as well as, receive events when there is a change of available components.
- An application shall set and disable the active component type, as well as, receive indication of any changes on the active component type.
- An application shall set the preference order for a specific component type (ex. English, German, etc on audio languages).
- An application shall be able to retreive information on the currently active component per type.
- An application shall be able to retrieve details on each component as depicted in the description section.
- The video tag shall be supported for both HTML and SVG
Dependencies: This use case has dependencies on the work on HTML5 video tag.
Additionally there has been work by Open IPTV Forum (OIPF) to standardize a embedded visual object for the control of MPEG2-TS in the DAE specification. This is provided as information.