h.264 level_prefix

[malikcis]

Hello,

In Iain E. Richardson's h.264 book "the h.264 advanced video compression standard",
details are missing in "Chap 7.4.2 -> 3.Encoding the levels of the remaining non-zero coefficients"
It states that Level VLC is composed of level_prefix and level_suffix, but he doesn't explain how level_prefix
is derived from level from encoding point of view. This part is hard to be reverse engineered from decoder spec.
Where can I find more precisions regarding this?

This topic has been discussed here previously without 100% accuracy:
http://forum.doom9.org/archive/index.php/t-111926.html

Thanks, malikcis

[imcold]

Look for the jvt document called "JVT-D034.doc", it contains example code for level_prefix/suffix construction.

[malikcis]

Thanks,
I downloaded the doc.
This kind of doc gives me headache at friday afternoon.
Found a nice PDF on that topic:
http://iris.ee.iisc.ernet.in/Courses/mm_2010/pdf/CAVLC_Example.pdf

Cheers

[Shevach]

Perhaps, it is interesting to know also what's maximal value of the level_prefix (since the maximal code size of level is derived from level_prefix).

In the document JVT-X210, in the item #83 is said:

Gary Sullivan suggests: People keep asking what the range of level_prefix is for FRExt profiles. It would be nice to figure out the answer and supply it in a NOTE. The same idea applies to other aspects where some helpful (but not strictly necessary) information has been left out of the standard – e.g., ranges of various things that are specified only indirectly but that need to be understood by implementers. Lowell Winger reports on 17 Oct 2006 that the maximum value of level_prefix is =19+(bitDepth – 8).