[mythtv] Decision on FFmpeg repository

Peter Bennett pb.mythtv at gmail.com
Fri May 18 17:58:48 UTC 2018



On 05/18/2018 12:05 PM, Gary Buhrmaster wrote:
> On Fri, May 18, 2018 at 3:38 PM, Peter Bennett <pb.mythtv at gmail.com> wrote:
> ....
>> To be able to easily accomplish this I think the best is a private
>> repository and a submodule to pull in the correct commit. The submodule
>> could be switched to a new branch easily when FFmpeg gets a new version. To
>> ensure that everybody gets the correct code when building, the "git
>> submodule update" could be in the configure script as suggested by
>> Jean-Yves. It will have to allow for building from a tarball, in that case
>> it will have to assume everything is up to date.
> I have not really followed this discussion (it is one for the actual
> devs, and ffmpeg has always been sufficiently problematic that
> I never had enough smarts to come up with a great alternative),
> but I do believe it is critical that when one does a download
> from github (at any particular commitish value(*)) one gets a
> fully complete source file without some later magic required to
> make it buildable by pulling in something new/different every
> time a build is performed, as it is expected that one can create
> a rebuildable source definition and use it as is to reproduce
> exactly the same binary (I am sure that is worded poorly).  If
> the configure script (potentially) pulls in new upstream every
> time, that breaks reproducibility.  Or maybe I am not getting
> what is being proposed (back to the I have not really been
> following this discussion).
>
>
>
>
> (*) For example:
> https://github.com/MythTV/mythtv/archive/862e510f589e3fedb8f37b61ac7967a219b7d8f4.zip
> which is (as of the moment) master head.
These git features are new to me, but as I understand it - If you add a 
submodule to a git repository, it makes one directory a copy of a 
specific commit in another repository. Submodule update will always 
fetch that specific commit. You can change it to another commit and you 
have to commit that change. If somebody has changed the submodule setup 
to access a different commit, somebody else who does a pull does not 
automatically get the updated source for the submodule, they have to do 
a git submodule update, this is why I would put that in the config. One 
specific commit from MythTV should always result in the same source code 
after the submodule update.

Peter


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