[FFmpeg-devel] [rfc] tasks for new ffmpeg developers

[Compn]

On Mon, 06 Feb 2017 13:22:31 +0000, Kieran Kunhya <kierank at obe.tv>
wrote:

> On Mon, 6 Feb 2017 at 05:54 Compn <tempn at mi.rr.com> wrote:
> 
> > people new to the project join #ffmpeg-devel and ask us for help on how
> > to start contributing to ffmpeg.
> >
> 
> A simple one is work on making decoders threadsafe (pthread_once on static
> inits).

can you (or someone) come up with a simple starter howto and some
doc or description for what exactly needs to be done? maybe is there a
commit to a decoder showing what was done to make it threadsafe?

the howto would detail how to test for threadsafe , what tools to use,
what an unsafe thread does or looks like in valgrind or gdb etc?
showing devs to use AVOnce and list other ff/av functions to fix unsafe
code.

grep FF_CODEC_CAP_INIT_THREADSAFE * to get the list of codecs that are
thread safe. the rest need to be done, in order of useful codecs first?

i'm not saying we have to hold everyones hand, but a little
documentation, direction and clarity will go a LONG way in getting
things worked on. :)

i know the ffmpeg devs can do all of this in their sleep, backwards.
but if you take the time to write down the steps you take, just
once, maybe someone will read, learn and come to contribute.

i found these quick posts about threadsafe code, maybe they help
the curious. or maybe they arent applicable to ffmpeg at all.

https://insights.sei.cmu.edu/sei_blog/2014/10/thread-safety-analysis-in-c-and-c.html
http://www.thegeekstuff.com/2012/07/c-thread-safe-and-reentrant/
http://www.thinkingparallel.com/2006/10/15/a-short-guide-to-mastering-thread-safety/

thank you
-compn