[streaming] Re: video on demand

[Derk-Jan Hartman]

Dermot McGahon wrote:

> On Wed, 25 Aug 2004 18:13:44 +0200, Nico <nsabbi at tiscali.it> wrote:
> 
>> still problems with the TS demuxer or is demux_rtp's fault?
> 
> 
> Sorry Nico. I should have known better than openly dissing
> mplayer in public :)
> 
> I think that demux_rtp is fine at this stage. In fact, video
> on demand is working *reasonably* well.
> 
> The next stage was to implement a new MRL type mcast:// for
> reading raw udp streaming over multicast. There is no rtsp
> for these streams, but I had to add a little code for the
> multicast group joins, and some code to handle the new
> MRL type.

The problem here is simple. This is the BIG design difference between 
VLC and mplayer you are running into I think.

Mplayer decoding as fast as it gets fed, and syncing on audio, VLC using 
the TS timestamping for 100% accuracy syncing...
You have to remember that VLC was MADE to playback MPEG2 TS UDP streams. 
  It's basically what it does best.

> The streaming tv server is just in a couple of weeks, and
> we've only moved from hubs to a proper multicast capable
> switch within the last week or two.
> 
> So, I was about to begin testing. However, business pressures
> now mean that I need a working udp multicast demo for next
> week .. this is a make or break demo, truely. So, I had a
> look at vlc this morning and it plays the udp multicast
> immaculately. The only slight problem is during channel
> change (we are changing channels using either the command
> line interface over ssh, or using the http interface) where
> on *some* channel changes there is resizing going on which
> looks a little bad. It may be aspect ratios, I need to
> investigate.

That might be the case yes. VLC usually is fed by one constant source, 
so it might not like handling this in every case...

> So, I am in the situation where I've modified one player
> (mplayer) to support rtsp/udp/unicast .. and it works
> reasonably well. I've modified the same player (mplayer)
> to handle udp/multicast .. but have problems during playback.
> 
> One time in five it will hold a/v sync and play for maybe
> five minutes before crashing.
> 
> The important stuff for next week is the udp/multicast and
> for that I am probably going to have to use vlc, because
> it works flawlessly. However, vlc will not (unless I code
> it up) handle rtsp/udp/unicast correctly.

Well depends. VLC can already do RTP mcast TS from the livedotcom client 
plugin. Most work for you is in the live.com plugin as we both know, and 
that can be easily reused. It's just a matter of making the right 
connections in livedotcom.cpp
If you run into problems, I'm sure fenrir or gibalou could be if some 
assitence if you just drop in on the IRC channel.

> So, I'm at a crossroads. Help stabilise mplayer or jump
> ship and implement rtsp/udp/unicast for vlc. I'm not sure
> what to do at this stage .. but you've always been helpful
> so the very least I can do is to submit some proper bug
> reports. I'll try and do that as soon as possible but it's
> unlikely to be until the week after next.

Good luck :)



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