[Live-devel] Media stream duplication on a streaming relay

[Bernhard Feiten]

Dear Ross, all,

attached you find a first uncomplete version of the StreamDup classes.
Perhpas you have some comments.  Is this in principle a way how to do it?
I'm quite unsure what needs to be regarded concerning the getNextFrame, 
aftergetting  filter chain mechanism.

Audio is working, but when I also activate the  video branch it crashes in 
H264VideoRTPSink
Must be error,  perhaps also somwhere else in my code.

Thank you for your comments,

Bernhard




----- Original Message ----- 
From: "Bernhard Feiten" <Bernhard at feiten.de>
To: "LIVE555 Streaming Media - development & use" 
<live-devel at ns.live555.com>
Sent: Thursday, August 07, 2008 7:59 AM
Subject: Re: [Live-devel] Media stream duplication on a streaming relay


> Dear Ross, all,
>
> as nobody answered I started to write a  StreamDup class following your 
> hints from the e-mail below.
>
> Related to that I have two questions?
> Would it be required that the sequnce number and timestamp of the 
> duplicates are newly initialized?
> Would RTCP also need to be considered then?
>
> Thank you in advance,
> Bernhard
>
>
> ----- Original Message ----- 
> From: "Bernhard Feiten" <Bernhard at feiten.de>
> To: "LIVE555 Streaming Media - development & use" 
> <live-devel at ns.live555.com>
> Sent: Thursday, June 26, 2008 7:28 AM
> Subject: Re: [Live-devel] Media stream duplication on a streaming relay
>
>
>> Dear Ross, all,
>>
>> did somebody wrote the StreamDuplication class you proposed below 
>> already?
>>
>> Do you have a hint how the getNextFrame functions could be synchronized?
>>
>> Thank  you very much,
>> Bernhard
>>
>>
>>
>>
>> ----- Original Message ----- 
>> From: "Ross Finlayson" <finlayson at live555.com>
>> To: "LIVE555 Streaming Media - development & use" 
>> <live-devel at ns.live555.com>
>> Sent: Thursday, December 08, 2005 8:57 PM
>> Subject: Re: [Live-devel] Media stream duplication on a streaming relay
>>
>>
>>> As you noticed, you can't duplicate a stream by having each recipient 
>>> read from a single object, because "getNextFrame()" can't be called more 
>>> than once on the same object concurrently.
>>>
>>> The solution, instead, is to create a separate object (of some 
>>> "FramedSource" subclass) for each recipient.  This new class would 
>>> implement the "doGetNextFrame()" virtual function by somehow 
>>> 'registering' with the data source object - to request a copy of the 
>>> next incoming frame.
>>>
>>> The data source object (which would *not* be a subclass of 
>>> "FramedSource", and so would not implement "doGetNextFrame()") would 
>>> handle these requests by delivering copies of each incoming frame to 
>>> each recipient, and not ask for a new incoming frame (from its upstream 
>>> data source) until it has finished delivering data to each downstream 
>>> recipient.
>>>
>>> For an example of code that is similar to this, note the relationship 
>>> between the "MPEG1or2Demux" and "MPEG1or2DemuxedElementaryStream" 
>>> classes. (In this case, however, we are demultiplexing data to 
>>> downstream recipients, rather than duplicating it.)  Note in particular 
>>> that (i) "MPEG1or2Demux" is subclassed from "Medium", not 
>>> "FramedSource", and (ii) "MPEG1or2Demux" implements a "getNextFrame()" 
>>> function that is similar to, but different from 
>>> "FramedSource::getNextFrame()".
>>>
>>> (This functionality (data duplication) is something that should probably 
>>> be added to the library someday.  Until then, however, you will need to 
>>> implement it yourself.)
>>>
>>>
>>> Ross Finlayson
>>> Live Networks, Inc. (LIVE555.COM)
>>> <http://www.live555.com/>
>>>
>>> _______________________________________________
>>> live-devel mailing list
>>> live-devel at lists.live555.com
>>> http://lists.live555.com/mailman/listinfo/live-devel
>>
>> _______________________________________________
>> live-devel mailing list
>> live-devel at lists.live555.com
>> http://lists.live555.com/mailman/listinfo/live-devel
>
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