[vdr] VDR and multicast streaming

Artem Makhutov artem at makhutov.org
Tue Oct 21 14:46:52 CEST 2008


Hi,

On Tue, Oct 21, 2008 at 11:48:45AM +0200, Frank Schmirler wrote:
> On Tue, 21 Oct 2008 09:13:15 +0200, Theunis Potgieter wrote
> > What is exactly involved in changing it from streaming to multi-
> > casting, isn't it just changing the IP destination? Or does it 
> > require repacking it from mpeg2-ts to something else? Sorry if this 
> > is a stupid question.
> 
> We are not limited to TS here - any of the formats streamdev can remux to
> should do.

The ADB-Boxes use Multicast-TS. I have captured a transmission from my
IPTV provider. So you can take a look on it:

http://www.makhutov.org/downloads/adb/

> I'd say the following things are required:
> - Use UDP instead of TCP for streaming (is it just switching from SOCK_STREAM
> to SOCK_DGRAM or do we need to do something more, e.g. fixed/max. packet sizes?)
> - Provide some way to select the channel for multicast transmission and stop
> it when it's no longer needed (probably via streamdev http server menu. Or do
> these kinds of settop boxes support some sort of control protocol to
> enable/disable the stream?)

The boxes send IGMP Join / Leave Group messages, if you switch or turn
on a channel.

Streamdev could listen for such messages an enable/disable the streams.

The IGMP Join Group messages are send in an interval (1 messege/minute).
If an IGMP Leave Group message is recieved, or if no Join Message was received
during 2 minutes then the stream sould be stopped.

The boxes also support HTML, so then can post data to a webpage, if the
channel was switched. I am not sure if all boxes support this. At least
the ADB boxes can do this.

The best would be implementing the stream stop/start by using IGMP as
this is part of the IP-Multicast standard, so in theory all multicast
clients should support it.

Regards, Artem



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