[x264-devel] Re: Response from a vendor

[Loïc Le Loarer]

Le Wednesday 21 June 2006 à 12:12:09 +0200, Peter Maersk-Moller a écrit:
> Hi
> 
> I'm trying to find a suitable Set Top Box to display my streams,
> which are created using mp4live (MPEG4IP) and x264. However
> a possible STB vendor has some problems showing my streams
> suggetings me to use Envivios encoder.
> 
> Does anyone here know a little bit about compability between
> x264 and Envivio or Main Concept ?
> 
> I suspect the STB vendor is missing implementing some of the H.264
> elements that x264 is supporting, but still investigating.
> 
> Anyone got a comment ?

Can you show use the options you use to encode your stream and a small
video dump of the produced bitstream ?

One of the possible option which can be a problem is the use of High
Profile (8x8 transform or scaling matrix particulary).

> --------------------------------------------------------------------
> > As a result of our tuning your encoded H.264 stream, unfortunately
> > it is not easy for us to make it compatible because your encoded
> > stream is not commonly available. Furthermore we have so far met
> > our compatibility to Main Concept(Germany) and Envivio(Canada)
> > both which are very commonly useful and standard. As you know each
> > Encoder vendor has a little different point. So IP-STB is
> > dependency on Encoder vendor.
> >
> > It is recommended that you may use the standard encoder, and Envivio
> > encoder has been updated as v2.0 of standard. Of course we have so
> > far tried out best to met to your encoded H.264 stream but we have
> > to modify quite some parts for you. Very sorry but we hope you would
> > take into consideraton about update of encoder
> --------------------------------------------------------------------

Please, everybody, don't be fooled by this kind of language, a decoder
must be compatible with the H.264 norm for given Profile/Level
combinaisons, being compatible with a given encoder is not an acceptable
answer, it is against interopability and have many bad results, a bit
like IE didn't support the whole HTML spec and added its own extension
creating "IE only" web sites.

Moreover, an encoder must also be compatible with H.264 norm and
produces bitstreams which are compliants with given Profiles and Levels.
If the Profiles and Levels of the encoder and the decoder matches, then
they can be used together.

In this case, it is possible that x264 produces an invalid bitstream or
that it uses an unsupported Profile or Level, or that the decoder
doesn't support a given valid construct that Main Concept and Envivio
encoders never produce and that the STB decoder doesn't support. In any
case, the correct part must be fixed, and the answer "use a compatible
encoder" is not acceptable. You should ask them to tell you precisely
why the streams you produce are not supported so that you can workaround
the problem until they fix it in they need to.

By the way, which STB vendor is it ?

Best regards.

-- 
Loïc

"heaven is not a place, it's a feeling"

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