Skip tests that require ffmpeg built with libvpx support also on Win with ffmpeg 8

[traversaro]

I was obtaining some test failures in conda-forge/torchcodec-feedstock#39, and it seems that some tests required ffmpeg built with libvpx support, to have a vp8 encoder, that is currently not available on Windows due to conda-forge/libvpx-feedstock#6 .

Indeed, it seems that for some reason the related tests were disabled for ffmpeg 6 and 7, while not for ffmpeg 8, even if also ffmpeg 8 on Windows does not have a vp8 encoder. I am not sure why upstream CI is passing, but this patch fixes the tests on conda-forge.

[traversaro]

I forgot to mark this PR not as Draft, but it is ready for review.

[NicolasHug]

Thanks for the PR @traversaro . I'm unsure what to do, it seems like these tests are passing fine in our CI (example run).

Looking at the output of ffmpeg -version in our logs and in yours, it seems like we're both also using the exact same build:

configuration: --prefix=/d/bld/ffmpeg_1758923948582/_h_env/Library ..........

Would you be able to print the value of avFormatContext_->oformat->video_codec before the call to

torchcodec/src/torchcodec/_core/Encoder.cpp

Line 619 in 169484d

avcodec_find_encoder(avFormatContext_->oformat->video_codec);

?