[x264-devel] Re: Response from a vendor

[Peter Maersk-Moller]

Hi Michael.

Thanks for your reply.

Michael Kazmier wrote:
> Hi Peter,
>> Does anyone here know a little bit about compability between
>> x264 and Envivio or Main Concept ?
> I have two Envivio encoders (B3 Professional) in house and we routinely 
> test against other encoders including x264.  The vendor is partially 
> right about the decoder being fine-tuned for different encoders. 
> Primarily the differences we have seen is that each encoder vendors 
> implementation of encapsulation (we use MPEG2 Transport Streams not 
> ISMA) is slightly different and that is where the real problem lays.

Yes, I have trouble getting STB vendors to fully support RTSP with
RTP delivery (and RTP over RTSP (TCP)).

AFAIK and IMHO, then as many vendors does, using RTSP to setup a
multicasted (or unicasted UDP) MPEG-2 TS is an abomination. I
don't even think it is described in the RTSP RFC as part of RTSP
and subsequently considering NOT part of the IETF Streaming Framework.

While UDP based streaming in theory is the correct way to do streaming,
in reality, it does not work (very well) unless the streamer controls the network
end to end, which few does on the Internet. UDP based streaming
particular fails over third party networks delivered as generic Internet
traffic where the last mile is using ADSL unless the stream is carried in
a reserved channel in a sort of TDM manner thus subsequently not
benefitting the statistical multiplexing behaviour of Internet
traffic.

> There are some suttle configuration changes you can make to force IDR 
> frames as well (in the Envivio for example).  So you'll want to make 
> sure that x264 is using a similar setting.  Also, I know that until 
> recently (two weeks ago) the Envivio encoder produce non-compliant B 
> Frames and this was a major hurdle as several STB vendors setup their 
> STB to "work around" the problem.

Somehow the non-compliance doesn't really surprise me, neither does the
STB workarounds - sadly.

 > For whatever reason, the industry has
>  pushed the modifications to the STB vendors and not the encoder vendors 
> - go figure.

Terms/conditions/property of life I guess.

>> I suspect the STB vendor is missing implementing some of the H.264
>> elements that x264 is supporting, but still investigating.

That almost have to be true. The trick is the find out which ;-)

> My suggestion is make the stream as simple as possible, use VLC with 
> MPEG2 TS output instead of ISMA 2.0...

Except UDP based streaming doesn't work (very well) as generic
Internet traffic over third party networks, especially where ADSL is involved.

> other than that, find a new STB 
> vendor?

Anybody know of a STB vendor that has a working STB supporting H.264
and RTSP and RTP over RTSP ?

Kind regards

--PMM

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