[x264-devel] Levels

[Mathieu Monnier]

Re,

> Do you agree that x264 should create H.264-conforming streams, unless an
> option not to is explicitly selected?  (leaving the question of the "minor
> constraints" aside for the moment...)

Since x264 was never used by default with a VBV, no, I don't agree with 
that. However, x264 should tend as much as possible toward that, but I 
don't think it's ready to do it right now.

If you leave aside VBV compliancy, x264 already generates conforming 
streams, and Loren's modification would make it choose the lowest 
appropriate level instead of 5.1.

> The test case is indeed extreme.  Most x264 users would filter that noise
> down a bit, no?

Good question. I would. But I know (lots of) users who think noise == 
grain and for whom grain must be preserved. Since they don't have FGM to 
their disposal, they can only encode it.

> BTW, how did you measure the 90 Mb/sec bit rate?  Is that a peak or an
> average, using a VBV model, or what?

Average frame size was between 300000 and 500000 bytes, with peaks of 
750000 bytes on intra frames.

> As for the minor constraints, ignoring them may have no practical impact
> most of the time,

Efficiency-wise, definitely. They are still a pain to code & validate.

Regards,

Mathieu