FFmpeg 5 on Windows errors in AudioEncoder's `avcodec_open2` when passing bad parameters

[NicolasHug]

We're getting segfaults or Windows fatal exception: access violation errors on Windows, with FFmpeg5, on the test_bad_input() abd test_bad_input_parametrized() tests of the AudioEncoder.

These tests purposefuly pass wrong parameter values for e.g. sample_rate or bit_rate. The error happens internally within the call to avcodec_open2():

https://github.com/pytorch/torchcodec/blob/05a6ff59baf7bf1ab7e44ca79b923c2a4474ca96/src/torchcodec/_core/Encoder.cpp#L213

I can validate that avCodecContext_, avCodecContext_.get() and avCodec are all non-null pointers before calling this. The error really seems to be within avcodec_open2() and not later, and not in the destructor either.

I'm not sure what's going on but I can reproduce the problem on different FFmpeg 5 versions. However, all of 4, 6, and 7 work fine.