[Live-devel] Presentation time when streaming video recording from surveillance cameras

[Michael S. Juul]

Hi Ross

 

We use the RTSPClient from Live555 to access live video and video recordings from surveillance cameras, utilizing the cameras built-in RTSP server and recording storage (An SD card).

We have a problem regarding the presentation time when streaming video recordings.

Let's say we have a video recording from "last week" which we would like to stream. We start the stream; we can even start the stream from a specific time in the video recording, so that's swell.

BUT, the presentation time we receive is "now", not "last week".

In order to display the correct presentation time, we therefore have to do a lot of calculations, which isn't very accurate (Sometime errors of several seconds).

In order to get a more precise presentation time calculation, I have tried to use the "durationInMicroseconds", but it seems to always be 0 (zero), and the getNormalPlayTime method always returns 0 (zero) because fNPT_PTS_Offset is 0 (zero).

Is there any way we can get the actual recording time (I.e. "last week") via Live555?

I am aware that this might in fact be a problem related to the cameras RTSP server, but I haven't been able to locate any setup properties in the cameras related to the presentation time when streaming video recordings, or for that matter live video. Also, one should imagine this is a normal usage scenario related to surveillance cameras, so when streaming a video recording, it should be possible to get the presentation time from when the video recording was actually made.

Any suggestions?

 

Venlig hilsen / Best regards

Michael S. Juul

B.SC.E.E

mj at unitek.dk <mailto:mj at unitek.dk> 

 

Unitek A/S

Vævervej 5

8800 Viborg

Tlf.: +45 86 61 44 22

mail at unitek.dk

www.unitek.dk <http://www.unitek.dk/> 

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