[vlc-devel] RTSP client 'trick play' support. When will it ever work??

Ross Finlayson finlayson at live555.com
Thu Jul 9 17:06:52 CEST 2009

>Le Thursday 09 July 2009 08:14:33 Ross Finlayson, vous avez écrit :
>>  So, the real problem is that VLC - in step 2 - is sending a "PLAY"
>>  command without an end time, despite the fact that the SDP
>>  description (returned in response to "DESCRIBE") had a range end
>>  time.  "ms->playEndTime()" *should* be non-zero (because "*ms" was
>>  created using the SDP description).  Could you please check this??
>If you want to play from beginning to the end, you should send 0-, not 0-end.

In this sentence, who do you mean by "you"?

If you mean that the client (VLC) is incorrect in 
how it's sending the "PLAY" request, then that 
contradicts what you say here:

>Step 3 is correct indeed - but step 2 is correct as well.

>I think the problem is that we are not distinguishing the timespan of the
>underlying media, obtained from the description from the timespan of the
>current play request. I dunno if it is a VLC bug, live555 misdesign, or both.

I don't really understand what you're saying 
here.  But, once again - to try to clarify - 
here's what's currently going on (at both the 
client and server ends).

0/ Client (VLC) -> Server

1/ Server -> Client (VLC):
	RTSP "DESCRIBE" response, with (in SDP):

2/ Client (VLC) -> Server
	RTSP "PLAY" with:
	Range: npt=0.000-

3/ Server -> Client (VLC)
	RTSP "PLAY" response with:
	Range: npt=0.000-

The problem seems to be that - in step 2/ - VLC 
is not including a range end in its "PLAY" 
request, despite the fact that 
"ms->playEndTime()" *should* be non-zero (because 
"*ms" was created using the SDP description).

Could someone please check:
	- Whether VLC is getting a correct value 
when it calls "ms->playEndTime()"?
	- and, if so, Why it's not including this 
in the subsequent "PLAY" request (and why it's 
not doing 'trick play' properly.

Ross Finlayson
Live Networks, Inc.

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