[vlc-devel] Re: VLC RTSP client support for Transport Stream 'trick play' operations
hartman at videolan.org
Tue Jan 16 15:45:36 CET 2007
On 12-jan-2007, at 21:14, Ross Finlayson wrote:
> FYI, the LIVE555 RTSP server implementation now supports trick play
> operations (seeking, fast forward, reverse play) on MPEG Transport
> Stream files. Note, for example, our new 'media server'
> application: http://www.live555.com/mediaServer/
> However, VLC - when playing these streams as a RTSP client -
> currently does not perform these trick play operations correctly
> from its GUI. Note that the LIVE555 RTSP client library fully
> supports trick play operations (note the optional "start", "end"
> and "scale" parameters to "RTSPClient::playMediaSession()"); it's
> just that VLC does not pass these parameters (in particular,
> "scale") when calling the library.
> Could someone please take a look at this? I suspect that a fix
> will be quite straightforward, and will give VLC important new
> functionality - basically, client support for VOD with trick play.
> It's important to note that - apart from the GUI, and the
> parameters passed to "RTSPClient::playMediaSession()" in the
> LIVE555 library - the fact that the server is performing a 'trick
> play' operation is completely transparent to the VLC client. I.e.,
> VLC's rendering code will continue to see what it thinks is a
> regular Transport Stream - with no discontinuity in PCR timestamps
> - so you won't need to make any changes there.
can we please not use the term "trickplay" ?? it's too confusing,
spans too many topics etc.
To decode: We need to support the optional paramaters start,end,scale
start is only in use atm when you do seeking. (DEMUX_SET_POSITION)
Just so i can get a few things clear.
1: if i set start=0, and the sdp specifies a starttime, is this still
automatically taken into account?
2: scale: this corresponds to normal FFW, RW functionality correct?
not to faster/slower (this would be speed?)
3: is there a way to know wether or not Scale is a supported option
by the server ?
VLC currently does FFW/RW by simply doing a seek. I need to put the
scale func. as a preferred method over the current functionality in
the core, which would be some simple additions. Glen Gray should
already have some code to start this of as a matter of fact.
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