[x264-devel] Re: Response from a vendor

[Peter Maersk-Moller]

Hi Loïc

Thanks for your comments.

Loïc Le Loarer wrote:
> Can you show use the options you use to encode your stream and a small
> video dump of the produced bitstream ?

Config is as follows:

   Geometry : 480x576
   SAR : 5:8
   Framerate : 25
   I-Frames : 2 * Framerate
   Bframes : 2
   Bitrate : 1200
   CBR : 1
   Rate tol : 0.01
   VBV : No
   Cabac : 1
   b_psnr : 0

60 secs. sample is available at http://www.optimalstream.net/tmp/sample.mp4

Sample is produced with x264-snapshot-20060424-2245. A bit old, but it should do.

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

How do I see that ?

> 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.

That's my line of thoughts. I'm trying to force the vendor to specify
exactly what levels and profiles that they support, but unsurprisingly,
some of them are vague on this.

> 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.

My line of thoughts. However since more parties are involved, I'm trying to build
the case with technological arguments.

> By the way, which STB vendor is it ?

At this moment, I'm not at the liberty to tell excepts its Korean. I'm trying to
find a vendor able and willing to deliver 1.000 H.264 STBs for a large scale
field test across a couple of countries in Scandinavia, but so far had little
luck. Many vendors have plans, but can't deliver a single working sample,
including Comtrend and Envivio which both have gone mysteriously silent
on the topic.

Kind regards

--PMM

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