6 Optimized handling of enclosure

26.1503GPPProtocols and codecsRelease 17Syndicated Feed Reception (SFR) within 3GPP environmentsTS

Tools: ARFCN - Frequency Conversion for 5G NR/LTE/UMTS/GSM

6.1 Introduction

SFR provides a method of advertising, before retrieval, all required codecs/profiles/levels within a media file reference. SFR also allows the description of either alternative enclosures or the definition of tailored syndicated feeds for specific devices capabilities..

Unless the client on the UE requests a special SFR defined alternate enclosure the handling of enclosure is independent of optimized reception, hence a regular ATOM/RSS server may be capable of providing feeds with optimized enclosure.

6.2 RSS enclosure

RSS schema has dedicated XML element for enclosure. "Enclosure" element in RSS [3] has three required attributes: "url", "length", and "type".

An SFR feed provider shall use the type attribute to specify the relevant 3GPP Mime type and Codec as specified in RFC 4281 of the referenced content that is in a 3GP format.

An SFR parser shall determine from the type attribute the mime type and codec associated with the referenced content and, upon determining whether the content is usable on the UE, retrieve it, if usable.

Example of RSS enclosure using RFC 4281 and TS 26.244:

6.3 ATOM enclosure

Enclosure in ATOM [4] is specified by using the "link" element with the "rel" attribute value set to "enclosure". The other three attributes of the "link" element used to specify enclosure parameters are "type", "length" and "href".

An SFR feed provider shall use the type attribute to specify the relevant 3GPP Mime type and Codec as specified in RFC 4281 of the referenced content that is in a 3GP format.

An SFR parser shall determine from the type attribute the mime type and codec associated to the referenced content and, upon determining whether the content is usable on the UE, retrieve it, if usable.

Example of ATOM enclosure using RFC 4281 and TS 26.244:

link rel="enclosure" type="audio/3gp; codec=" samr " " length="1337" href=http://example.org/audio/ph34r_my_podcast.3gp

6.4 Providing alternative enclosures

Content Provider can publish media content in multiple formats, some matching UE capabilities, some not. There are three methods to provide tailored enclosures for UE capabilities:

– Alternative description in the syndicated feeds: The syndicated feed is extended to include multiple versions of the same content. An example is provided below for ATOM. Other ways are possible for both ATOM and RSS.

– Alternative syndicated feed channels: The feed aggregator creates tailored syndicated feeds, which all match the device capabilities.

– Alternative delivery of enclosure based on the requesting device: The server selects the correct version of the content, when the device requests the enclosure.

The feed provider or the SFR server may offer syndicated feeds tailored for device classes. The SFR server in case of optimized delivery can use the DCD content type and DCD-Mime Types parameters to associate the registering device to the matching tailored syndicated feed.

Additionally, the syndicated feed server may offer alternative versions of media content, either based on the knowledge of UE capabilities or just based on alternative version availability.

In such a case, the enclosure support in ATOM/RSS will be reused for primary enclosure as per section 6.2 and 6.3 above.

Alternative enclosures could be used to specify alternative formats for the media content.

An syndicated feed server may include alternative enclosure in the RSS feed:

– if it is aware of the UE capabilities and there are multiple available versions of the same media content in formats usable by the UE. This applies both to the optimised and non optimised delivery mode.

– or if the SFR server is not aware of the UE capabilities and the format of media content in primary enclosure may not be usable by the UE. This may apply to the non optimized delivery mode.

An SFR enabled Feed Reader should add the UAProf header [11] to all HTTP requests. If a feed provider or SFR server wants to personalize the response to device capabilities, the server should interpret the UAProf header and send an according response, e.g. enclosure codecs settings, which match the device capabilities.

It is also possible to describe multiple enclosures in the syndicated feeds. For instance, the ATOM format [4] allows providing multiple enclosure links in a single entry for the purpose of providing alternative media formats or content formats relating to the Entry.

An alternative enclosure in SFR for ATOM can be defined as follow:

– Multiple "rel" attributes with values set to "enclosure" are used in a single parent entry element.

– The "type" attribute value in the enclosure links are specified according to section 6.1

Example of alternative enclosure in ATOM:

<entry>

</entry>