IltmmRTSPServer::get_LiveLatency

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#include "ltmm.h"

C Syntax	HRESULT IltmmRTSPServer_get_LiveLatency(This, index, pValue)
C++ Syntax	HRESULT get_LiveLatency(index, pValue)

IltmmFilterEnum *This;	/* pointer to the interface instance */
long index;	/* index of the source */
double *pValue;	/* pointer to a variable */

Retrieves the latency used for streaming live streams.

Parameter	Description
This	Pointer to the IltmmRTSPServer Interface.
index	0-based index of the source folder whose latency should be retrieved. Use -1 to retrieve the default live latency.
pVal	Pointer to a variable to be updated with the live latency (in seconds).

Returns

S_OK	The function was successful.
<> S_OK	An error occurred. Refer to the Error Codes or the HRESULT error codes in the DirectShow documentation.

Comments

The RTSP server treats growing DVR buffers as a live stream. When a RTSP client connects and requests playing a growing DVR buffer, the RTSP server starts playing from the current position in this live stream. For performance purposes, it starts a little bit behind the live stream. The amount by which it is behind the is called "live stream latency" and its amount is retrieved using this function. The live stream latency is a double value and is measured in seconds.

This function allows you to get the live stream latency for a source (if index is between 0 and SourceCount - 1) or for the server (if index is -1).

The default live stream latency is 0.5 (meaning the live stream is 0.5 seconds behind the live stream).

A DVR buffer is considered to be growing if it is still being written to by the DVR engine when a RTSP client requests it.

See the Programming with the LEADTOOLS DVR Module topic for more information on DVR files.

If the source DVR buffer is using a compression compatible to the RTSP server, the streaming will start from the first key frame found before the "Live Stream Position" - "LiveLatency". This is done for performance purposes, because the streaming must start with a key frame.

Required DLLs and Libraries

LTMM

For a listing of the exact DLLs and Libraries needed, based on the toolkit version, refer to Files To Be Included With Your Application.

Platforms

Win32, x64