[Live-devel] How to distinguish new RTP packets fromout-of-data RTP packets when random accessing the video

[Erin Yang]

Yes. It happened. Sometimes, network traffic may be congested.

When randomly accessing the video, we can’t guarantee the last old RTP packets arrive earlier than the first new RTP packet due to congested network.

If I just feed all incoming data to decoder, as usual, the player would display the old video frame in the new position.

So, we need more information (e.g. RTP header, command response…) to overcome the problem resulting from congested network.

 

-----Original Message-----
From: live-devel-bounces at ns.live555.com [mailto:live-devel-bounces at ns.live555.com] On Behalf Of Ross Finlayson
Sent: Saturday, January 07, 2012 5:46 PM
To: LIVE555 Streaming Media - development & use
Subject: Re: [Live-devel] How to distinguish new RTP packets fromout-of-data RTP packets when random accessing the video

 

I would like to random access the video, so I send a PAUSE command and then a PLAY command with a specified time.

That is like follows.

 

PAUSE rtsp://113.31.34.14:554/work/500/115/969/967/500.3gp RTSP/1.0
SeqNo: 3
Session: 6347526623097789397
(==> without range header)
 
...
 
PLAY rtsp://113.31.34.14:554/work/500/115/969/967/500.3gp RTSP/1.0
SeqNo: 4
Range: npt=12-100    (==> set start play point at the 12th second)
Session: 6347526623097789397
 
 
However, I can’t control the network traffic, so I may still receive some old RTP packets after receiving PLAY response.

 

Are you actually seeing this happen with this server (a Darwin Streaming Server)?    Our RTP reception software will automatically discard out-of-order incoming RTP packets (by checking the RTP sequence number).  So, if you're seeing "old RTP packets" after the "PLAY", then presumably you're seeing some 'old RTP packets', followed by only 'new RTP packets'.  You should not be seeing 'old RTP packets' mixed with 'new RTP packets'.

 

In this case, I wouldn't worry too much about this.  It's unlikely that you're seeing very many 'old RTP packets' (unless your server is badly broken), so you can probably just feed all incoming data to your decoder, as usual, and things should be OK.  It'll be merely as if you slightly delayed sending the "PAUSE" command.

 

 

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

 

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