OIPF 规范翻译（DAE）-----4.4.5 Media control

4.4.5 Media control
Instantiation of a video/broadcast or A/V Control object does not cause any scarce resources to be claimed. Scarce
resources such as a media decoder are only claimed following a call to the setChannel(), nextChannel() or
prevChannel() methods on a video/broadcast object or the play() method on an A/V Control object. By
implication, instantiating a video/broadcast or A/V Control object does not cause the media referred to by the
object’s data attribute to start playing immediately. See section 7.13.1.1 for details of when scarce resources are released by a video/broadcast object and section 7.14.1.1 when scarce resources are released by an A/V Control object. Where applications make conflicting requests for limited media decoding resources, the media decoding resources that are requested most recently are presumed to be the ones that are most wanted and the resources SHOULD be granted to the application that most recently requested them regardless of the priority of the application indicated in application signalling. Any objects which have lost the resources shall generate an error (e.g. error code 11 in the case of the video/broadcast object, or error code 3 in the case of the A/V Control object) and, in the case of the video/broadcast object, return to the unrealised state. This applies to conflicts between different requests for
streaming video or audio (whether over RF tuners or IP streams). When an error occurs due to scarce resources being removed from an object, the object SHALL free any other scarce resources that may be held. Multiple applications from the same author which are running simultaneously should co-ordinate their use of scarce resources. This specification is intentionally silent about handling of resource use by embedded applications including scheduled
recordings.  If audio from memory interrupts any other media presentation then the interrupted presentation SHALL be restored automatically by the OITF when the interrupting presentation ends. When audio from memory is interrupted by a resource loss, or when streaming video or audio presentation is interrupted by a resource loss caused by another request for streaming audio or video presentation, the presentation is cancelled and
SHALL NOT be restored automatically by the OITF.