ISO C++ forbids compound-literals. It's not available with MSVC.
This is a known issue from 10 years ago, and that's why there is a
av_get_time_base_q().

Since we have no plan to remove AV_TIME_BASE_Q, just make it
available in C++.

There are multiple choices:
1. Use C++11 syntax: AVRational{1, AV_TIME_BASE}

Users may still use C++98 to write new code. So no.

2. Use av_get_time_base_q().

It's for this purpose. But it's not compile time constants as
AV_TIME_BASE_Q in C.

So I choose av_make_q() as Anton's suggestion.

https://libav-devel.libav.narkive.com/ZQCWfTun/patch-0-2-fix-avutil-h-usage-from-cSigned-off-by: Zhao Zhili <zhilizhao@tencent.com>