[mythtv] Decision on FFmpeg repository

[David Engel]

On Fri, May 18, 2018 at 11:20:57AM -0400, Peter Bennett wrote:
> On 05/17/2018 04:33 PM, John P Poet wrote:
> > 
> > If David and Aman are willing / able to get our patches pushed to
> > FFmpeg, then this <hopefully> would become a non-issue, since we could
> > just add an external dependency on FFmpeg, instead of including it. 
> > Again, that is probably not practical, though.
> 
> I sent Aman files of our patches a few days ago. He noticed a couple that he
> suggested I submit to FFmpeg.
> 
> 1. One header file now causes c++ compiles to fail.
> Response from them - the header file we have been using is not public and
> should not be used by us. Patch rejected.

Disappointing, but understandable.  What do we use that header for?
Is it for any of the other things that Aman has already implemented or
is implementing differently than us?

> 2. Three external names misspelled in a .v file - resulting in a link error
> Response from them - those functions are not part of the public api and they
> are no longer used - they should be removed.

Again, understandable.  Do we use any of those functions?

> I believe that in the past, MythTV developers have noticed useful things in
> the FFmpeg code, and called functions or used structures without regard to
> whether they were the official API. Now those functions are being changed or
> removed we are scrambling to fix the result. It may be better to copy useful
> functions into our code rather than simply call them in the ever changing
> FFmpeg code.

Both ways have their problems.  Copying functions into our code can
give a false sense of security.  There aren't any conflicts with the
latest update -- yay.  Oh no, several things broke silently in suble
ways.

> We should only be using the external API that is exposed by the header files
> they deploy as part of FFmpeg build. We are using the header files in the
> FFmpeg source.

I completely agree with this.  That means trying hard to get the
missing functionality we need accepted upstream and being willing to
drop some of our extra functionality if we can't get it accepted.

David
-- 
David Engel
david at istwok.net