Presentation Context

The presentation context contains name-value pairs that describe the content requested by a client. There is one context for each client. The following table identifies the context values defined by Windows Media Services.

Name	Value (data type)	Key	Description
WMS_PRESENT_BITRATE	long	11	Contains the maximum bit rate for the streams sent to the client. This value is constant and is determined by the server at the start of the presentation.
WMS_PRESENT_BROADCAST	long	6	Contains a value that specifies whether a presentation is a broadcast. A value of 1 indicates true and 0 indicates false.
WMS_PRESENT_CONTENT_DESCRIPTION	IUnknown*	3	Contains an IUnknown pointer that you can use to retrieve a pointer to an IWMSContentDescriptionList interface. You can call the GetAndQueryIUnknownValue method on the IWMSContext interface to retrieve a pointer to IWMSContentDescriptionList.
WMS_PRESENT_DURATION_HI	long	12	Contains the high-order 32 bits of a 64-bit integer indicating the maximum possible time, in milliseconds, that the presentation can last. This value is only set if the presentation extends beyond approximately 1200 hours.
WMS_PRESENT_DURATION_LO	long	13	Contains the low-order 32 bits of a 64-bit integer indicating the maximum possible time, in milliseconds, that the presentation can last. This value is set for each item in the playlist.
WMS_PRESENT_ORIGINAL_PHYSICAL_NAME	String	16	Contains the content location retrieved after the URL requested by the client is resolved to a publishing point. This is the original local source that is retrieved after expanding a publishing point. This is the physical URL before a Physical URL Transform is performed.
WMS_PRESENT_ORIGINAL_REQUEST_NAME	String	17	Contains the URL requested by the client.
WMS_PRESENT_PHYSICAL_NAME	String	4	Contains the URL for the presentation.
WMS_PRESENT_PLAY_RATE	double	14	Contains the rate at which the presentation is streamed. A value of 1 indicates normal forward speed. A value greater that 1 indicates that the content is being fast-forwarded. A value less than 0 indicates that the content is being rewound. For example, a value of 2 indicates that the content is being fast forwarded at twice the normal rate, and -2 indicates that it is being rewound at twice the normal rate. This value is copied from the WMS_COMMAND_CONTEXT_RATE context value.
WMS_PRESENT_PLAYLIST_ENTRY_ROLE	String	45	Contains the role attribute in a playlist.
WMS_PRESENT_PREROLL_TIME	long	81	Contains the amount of preroll time, in milliseconds, specified in the Windows Media file header for the content. The preroll is initially determined by Windows Media Encoder and represents the amout of content that must exist on the client before the content can be played.
WMS_PRESENT_REDIRECT_LOCATION	String	70	Contains a URL sent by the cache manager in response to NS_E_REDIRECT. For more information, see Implementing Reverse Proxy.
WMS_PRESENT_RELIABLE	long	8	Contains a flag that indicates whether the digital media stream must be carried over a reliable data communications transport mechanism. The value of the flag is 1 for true and 0 for false.
WMS_PRESENT_REQUEST_NAME	String	5	Contains the URL requested by the client.
WMS_PRESENT_SEEKABLE	long	7	Contains a flag that indicates whether the end user can seek to a specific time offset in the digital media stream. The value of the flag is 1 for true and 0 for false. Only on-demand content is seekable.
WMS_PRESENT_START_TIME	QWORD	15	Contains the start time of the presentation. This is the start time of the play request, in milliseconds, as an offset from the beginning of the stream. This might not be present in all play requests.
WMS_PRESENT_STREAM_HEADERS	IUnknown*	2	Contains an IUnknown pointer that you can use to retrieve a pointer to an IWMSStreamHeaderList interface. The IWMSStreamHeaderList interface contains a collection of IWMSStreamHeader objects that describe each item of content in a presentation. You can call the GetAndQueryIUnknownValue method on the IWMSContext interface to retrieve a pointer to IWMSStreamHeaderList.
WMS_PRESENT_TOTAL_BYTES_SENT_HI	long	18	Contains the high-order 32 bits of a 64-bit integer containing the total number of bytes that have been sent to the client.
WMS_PRESENT_TOTAL_BYTES_SENT_LO	long	19	Contains the low-order 32 bits of a 64-bit integer containing the total number of bytes that have been sent to the client.
WMS_PRESENT_TOTAL_PLAY_TIME_HI	long	20	Contains the high-order 32 bits of a 64-bit integer containing the total presentation time, in seconds.
WMS_PRESENT_TOTAL_PLAY_TIME_LO	long	21	Contains the low-order 32 bits of a 64-bit integer containing the total presentation time, in seconds.
WMS_PRESENT_WMSSINK_SELECTED_BITRATE	DWORD	51	Contains the bit rate of the content that is being sent to the client.

See Also (General)

• Contexts

• Implementing Reverse Proxy

• role

See Also (Visual Basic .NET)

• IWMSContentDescriptionListIWMSContentDescriptionList Object (Visual Basic .NET)

• IWMSContext.GetAndQueryIUnknownValueIWMSContext.GetAndQueryIUnknownValue (Visual Basic .NET)

• IWMSStreamHeaderListIWMSStreamHeaderList Object (Visual Basic .NET)

See Also (C#)

• IWMSContentDescriptionListIWMSContentDescriptionList Object (C#)

• IWMSContext.GetAndQueryIUnknownValueIWMSContext.GetAndQueryIUnknownValue (C#)

• IWMSStreamHeaderListIWMSStreamHeaderList Object (C#)

See Also (C++)

• IWMSContentDescriptionListIWMSContentDescriptionList Interface

• IWMSContext::GetAndQueryIUnknownValue

• IWMSStreamHeaderListIWMSStreamHeaderList Interface