[theora-dev] PostProcessingLevel field of PB_INSTANCE

[tterribe at vt.edu]

Quoting Leonardo de Paula Rosa Piga <lpiga at terra.com.br>:

> What is the PostProcessingLevel field of PB_INSTANCE?
>
> When is it used?
>
> It is used for all Theora's video or it is just for legacy support with VP3?

PostProcessingLevel enables post-processing filters on the final decoded frames
(de-blocking and de-ringing). These help improve image quality, but are very
computationally intensive due to the number of memory accesses required, and so
are disabled by default (PostProcessingLevel=0). See pp.c for details. The old
libtheora API did not expose any method of changing this default value.

The new theora-exp decoder (now in mainline svn) exposes an API for dynamically
setting the post-processing level (e.g., according to available CPU time). See
TH_DECCTL_GET_PPLEVEL_MAX and TH_DECCTL_SET_PPLEVEL in theoradec.h or at
http://people.xiph.org/~tterribe/doc/libtheora-exp/theoradec_8h.html#decctlcodes