[FFmpeg-devel] [PATCH 0/3] Finish new iteration APIs

[Michael Niedermayer]

On Sun, Feb 18, 2018 at 05:58:16PM +0000, Josh de Kock wrote:
> This should be the last of the major API changes. I'm not entirely
> sure if I missed anything. 

Moving from a register based system where a user app can register
any subset to a system which registers all via an array will 
increase the size of statically linked binaries for users only
using a subset.

An example of this effect for codecs is tools/target_dec_fuzzer.c

This effect results because when the linker collects all objects
of all static libs with a user application it can remove all symbols
which are not referenced.
If there is a single array that references all codecs, filters, formats
and this array is referenced by a function which must be used then
nothing can be removed at the link stage

OTOH with a register function a register all which refernces all
a user application can simply not use the reference all code and register
the specific subset it needs with individual register calls.
In this case the linker can ommit the register all and all codecs, formats
and filters teh user application does not explicitly refer too.
In the case where this applies this results in significantly smaller files

I also expect they link faster and load faster but i forgot to benchmark this
when i realized this issue exists and tested ...

I am thus in favor of a system that does not unconditionally reference every
codec/format/filter

There can also be an advantage security wise if unneeded parts are never
"registered"

[...]
-- 
Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

Many things microsoft did are stupid, but not doing something just because
microsoft did it is even more stupid. If everything ms did were stupid they
would be bankrupt already.
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