[vlc-devel] Re: Trick mode support for MPEG2 TS

[yj]

As a simple implementation, I think Fast Forward can
be implemented by only decode I-Frame(if we need
faster forward, we may discard some I-Frames...),
But in this mode, how can we implement Slow Play?
and how to determine which frame is I-Frame? I didn't
find any flags for frame type in the MPEG2 TS frame
structure, can you help me?
Also, how to determine the whole length of the TS
stream?


--- Christophe Burgalat
<c.burgalat at broadcastavenue.com> wrote:

> The TS Muxer and the mpeg video packetizer plugin,
> used to stream out, does 
> not support fast forward for example.
> It need some developments but I'm not even sure it
> is possible...
> It seems possible to recalculate PTS/DTS values in
> mpeg video packetizer 
> pluign (I've tried it, it seems ok), but what about
> the frame rate value ? 
> Should VLC send only one frame on two with a x2
> speed ? Should VLC send only 
> Intra picture when sending with x4 speed to limit
> bandwidth usage ? I have no 
> idea on how to implement it.
> 
> Christophe
> 
> Le Lundi 6 Mars 2006 06:09, yj a écrit?
> > It seems that VLC can play MPEG2 TS file with
> trick
> > mode support, and, the VLC can stream out streams,
> > is it possible for adding RTSP server support for
> VLC?
> >
> > --- Måns Rullgård <mru at inprovide.com> wrote:
> > > Christophe Burgalat
> <c.burgalat at broadcastavenue.com>
> > >
> > > writes:
> > > >> On Fri, 2006-03-03 at 02:00 -0800, yj wrote:
> > > >> > Hi,
> > > >> > I would like to know how to implement the
> Trick
> > >
> > > mode
> > >
> > > >> > support for MPEG2 TS stream.
> > > >> > Actually, I want to get a RTSP server with
> the
> > >
> > > above
> > >
> > > >> > feature.
> > > >>
> > > >> There have been patches submitted by
> > >
> > > glen at lincor.com to provide
> > >
> > > >> trickplay support with vlc and Kasenna
> servers.
> > >
> > > Works well.
> > >
> > > >> Kasenna's are not cheap though.
> > >
> > > And there is no end to the pains they cause if
> you
> > > buy them.
> > >
> > > > Yes but this patch only concerns VLC as a
> client,
> > >
> > > I'm right ?
> > >
> > > > It seems to be possible to integrate this
> feature
> > >
> > > also in VLC as a RTSP
> > >
> > > > server.
> > > > I began to try developping it (in fact, fast
> > >
> > > forward only) and even if it
> > >
> > > > sometimes work well, I'm not sure to do it the
> > >
> > > right way... I wonder how
> > >
> > > > Kasenna server implements this feature.
> > >
> > > The Kasenna server creates special fast forward
> and
> > > rewind streams by
> > > extracting I frames from the original file and
> > > fudging timestamps.
> > > When a client requests a trick mode the server
> > > switches to the
> > > corresponding place in the ff or rew stream. 
> The
> > > server also creates
> > > indexes that let it quickly map between
> timestamp
> > > and file offset for
> > > each of the streams.  At least this is all how
> it is
> > > supposed to work.
> > > It is very easily confused, and can get the
> indexes
> > > offset by several
> > > minutes.  And that's when it doesn't lock up in
> > > bizarre ways.
> > >
> > > --
> > > Måns Rullgård
> > > mru at inprovide.com
> > >
> > > --
> > > This is the vlc-devel mailing-list, see
> > > http://www.videolan.org/vlc/
> > > To unsubscribe, please read
> > > http://developers.videolan.org/lists.html
> >
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