[Live-devel] how to get dts in LIVE555 Streaming Media

[Ross Finlayson]

> I am using testRTSPClient to connect rtsp server,then get h264 video frame,in the "DummySink::afterGettingFrame()" function i already get h264 data and pts(presentationTime timestamp),however,i want to get dts(decoding time stamp) also,but where is the dts? 

The DTS (decoding time stamp) is not carried in the RTP stream.  Instead, it is the job of the receiver’s decoder to compute this.

Note that the incoming H.264 NAL units (as in all RTP video streams) arrive in 'decoding order’ (i.e., the order in which they are to be fed into the decoder), not ‘display order'.  This means, for example, that it’s possible (if the video stream contains ‘B frames’) for the NAL units’ ‘presentation times’ to be in non-monotonic order (i.e., sometimes decreasing).

Because you know that the incoming NAL units are in ‘decoding order’, then your decoder should be able to compute the ‘decoding time stamp’ from the ‘presentation time stamp’, if desired.

Ross Finlayson
Live Networks, Inc.
http://www.live555.com/ <http://www.live555.com/>
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