Seek Requirements
Most users today are accustomed to operating VCRs and DVRs. There is an expectation that the device should enable the user to seek to a location in the audio or video stream. Minimally, Windows 7 logo requirements state that a DMR device must support time-based seeking for WMA and WMV content with ProfileIDs that are defined in NETMEDIA-0023 and NETMEDIA-0024. Support for seeking can be done locally by using cached content, through HTTP requests against the server or a combination of both (NETMEDIA-0070).
The time-based seek protocol for DMR devices and DMC device interactions is described in DLNA document CR13 (under the name ”controller-time seek operations”). CR13 will be published as Errata #3 to the DLNA 1.5 Guidelines. DMRs must follow the requirements for controller-time seek operations that are defined in CR13.
The Windows 7 NSS supports seeking to use a conventional HTTP range request as defined in section 14.35 of the HTTP 1.1 specification. It also supports the DLNA-defined HTTP extension header, TimeSeekRange.DLNA.org. Depending on the content type, the NSS provides none, one of the two, or both seek methods. The DMR must verify the appropriate seek method before it tries to seek within the content item.
Although the Windows 7 logo requirements require seek support for WMA and WMV profiles, for other profiles, DMR devices should support time-based seeking.
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