Feature Request: Support audio channel mask with Avs+ r4001

[tebasuna51]

The last Avs+ r4001 support the audio property Channel Mask included in VideoInfo struct.

See the new Avisynth.h in https://github.com/AviSynth/AviSynthPlus/blob/master/avs_core/include/avisynth.h
to know how it is stored in the existing int image_type.

Audio decoders must fill that info like do in audio_output.cpp:

...
vi->nchannels = output_channels;
vi->audio_samples_per_second = aohp->output_sample_rate;
...
Now we need:
vi-> image_type = ...

[Asd-g]

Try the attached version.

LSMASHSource_test.zip

[tebasuna51]

Seems work fine for me with some samples ac3, eac3 and dts
I'll continue testing with other samples.

[FranceBB]

Thanks for the Channel Mask property support, works like a charm in the stable build. :)
Now we just need ffmpeg support and we're good to go in production. :D