[MPlayer-users] about multicast

[Carl Karsten]

Why the top post all of a sudden? anyway...

So you want multiple machines to play something and all be in sync.

I hear that can be tough.  I think it isn't so much a technical problem, just a 
lack of application support problem.  most people don't need it, so it isn't 
addressed.  most people are playing across the Net, so a durable connection (so 
buffering) is more focused on.


I can think of a mod that could be made to mplayer that would solve your problem:

-StartTime yyyy:mm:dd:hh:mm:ss:tt

mplayer will keep the start of the file in sync with that datetime.

So if the Start is in the future, mplayer will wait.
If it is in the past, mplayer will seek into the file.

I wonder if mplayer will drift such that it looses a second after some amount of 
playing?

Now instead of trying to stream over your lan, just use some file system protocol 
and let each mplayer have access to the file.

But looking at your post, I am not sure what your input is - file or stream?

If it is a stream, then you need some sort of time stamp imbeded in the stream.

^C

ps. I suggest you rearrange the top/bottom and trim some of the needless parts 
from your next post.

Sinan Nalkaya wrote:
> hi , thank you for great idea but there is a problem about that, when
> the client starts to play this file, it will start to play the start of
> stream.dump file, this causes a problem because if one of the clients
> crashes or reboots, it will loose the synchronization. i`m planning this
> system to be kind of  billboard, 4-5 pc monitor will show the part of
> the mpeg file, so each of them must play in synchronized. is mplayer
> able to play the end of file ? or should i hack the mplayer source and
> open the file like O_APPEND flag, so it may start to play at the end of
> file ?
> ps: every clients have exactly same hardware and same os (they boot from
> nfs)
> thanks for replies.
> On Tue, 2006-01-03 at 09:11 -0600, Kichigai Mentat wrote:
> 
>>-----BEGIN PGP SIGNED MESSAGE-----
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>>On Jan 2, 2006, at 16.18, Sinan Nalkaya wrote:
>>
>>
>>>On Mon, 2006-01-02 at 14:27 +0100, Nico Sabbi wrote:
>>>
>>>>Sinan Nalkaya wrote:
>>>>
>>>>
>>>>>hi i have 2 clients. all i want is capture the multicast streams  
>>>>>at same
>>>>>time, with -nocache parameter it seems not bad, but sometimes,  
>>>>>one of
>>>>>them becomes more laggy than the other one, what do you suggest  
>>>>>me for
>>>>>this and do you know good multicast program ?(currently using  
>>>>>ffmpeg)
>>>>>but output of dvbstream program seems fine.
>>>>>note: both pcs are same configuration with same hardware
>>>>>thanks.
>>>>>
>>>>>
>>>>
>>>>-dumpstream will work fine, instead direct playback can exhibit  
>>>>problems
>>
>>[snip]
>>
>>>thank you for answer,
>>>it seems with this option i cannot play streams on the fly with 2
>>>computers , syncnorized ? or should i open another mplayer to play  
>>>this
>>>file ?
>>
>>Well, if you were going to playback the stream, you would need a  
>>second instance of mplayer running. Luckily enough, -dumpstream uses  
>>very little resources compared to a full on decoding and saving.
>>
>>Playing them synchronously will be a major hassle, though. Unless  
>>both computers have the exact same specs, and are not competing for  
>>bandwidth, it can be quite a challenge. But, here's something to  
>>consider. Why not introduce a third computer. It doesn't need to be  
>>anything fancy, probably something as weak as a Pentium 166 could do  
>>this job. Just throw the three computers onto a LAN, have the third  
>>computer I mentioned simply just use the -dumpstream option, and have  
>>the other two computers play off of dumped stream. This would take  
>>care of any problems with bandwidth, and would ensure that both  
>>computers are receiving an identical stream. The only catch here, is  
>>that you'd have to start both players at exactly the same time, but  
>>I'm sure there's some kind of script or use of an application  
>>scheduler you could use to handle this for you.
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> 
> 
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