[FFmpeg-devel] [PATCH 1/2] lavc/pcm_tablegen: slight speedup of table generation

Clément Bœsch u at pkh.me
Mon Jan 4 10:29:46 CET 2016

On Sun, Jan 03, 2016 at 09:49:33PM -0800, Ganesh Ajjanagadde wrote:
> On Sun, Jan 3, 2016 at 1:30 PM, Carl Eugen Hoyos <cehoyos at ag.or.at> wrote:
> > Carl Eugen Hoyos <cehoyos <at> ag.or.at> writes:
> >
> >> Ganesh Ajjanagadde <gajjanag <at> mit.edu> writes:
> >>
> >> > No one has told me what is interesting
> >>
> >> Did you look at tickets #4441 or #4085?
> >
> > Or ticket #4829 or a j2k issue?
> Thanks a lot for taking the time to point these out. They have all
> been noted. Unfortunately, I have too many things on my list now. 4829
> may be what I tackle first; it may take a while though.
> I hope the following is helpful.
> Generally, my strengths are in algorithmic/mathematical/numerical
> improvements. 

but not interested in merging pre-filter and RLB-filter in EBU R128 like I
pointed out? :(

More seriously, maybe try to write a filter? I'm thinking of the Eulerian
magnification filter¹², which I unfortunately haven't time to work on.

You may also enjoy studying motion interpolation for many applications.

Anyway, the point is, you have a very large range of possibilities to
enjoy yourself on the project wrt image processing.

[1]: http://people.csail.mit.edu/mrub/vidmag/
[2]: https://www.youtube.com/watch?v=ONZcjs1Pjmk

> I have a strong interest in security (both its
> "practical" and "theoretical" variants), but with nowhere near the
> same level of knowledge.
> Clarifications: by algorithmic improvements, I do not usually count
> asm code, but make exceptions in some cases. In particular, I have
> minimal knowledge of assembly and minimal motivation in learning it.
> However, I may examine at some point cases where I am convinced that a
> compiler can't do the needful.
> By theoretical aspects of security, I refer to defensive programming,
> some forms of undefined behavior (e.g rint64_clip, many ubsan
> failures), and other such things such as those flagged by Coverity. By
> practical aspects of security, I refer to things like fuzzing crashes,
> other ubsan failures, and other things flagged by Coverity or found by
> audit.

Well, I have a challenging suggestion then... How about looking at
threading? Look for Helgrind (or DRD) on http://fate.ffmpeg.org. I know
many of the report are false positive... but are they? Do we have real
issues spotted here? You might want to study why we have so much of them,
if ints read/write really are actually atomic on all platforms, ... that
sort of stuff :)

Clément B.
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