Possible 2 bugs in Linux & vapoursynth

[Selur]

1st please use the 'code'-tags to make your post better readable. It's a pain.
About the issues:

But IMHO, prefer_hw is an argument for LSMASHSource, not LWLibAVSource ?

I have no problem using:

# Imports
import vapoursynth as vs
core = vs.get_core()
# Loading Plugins
core.std.LoadPlugin(path="I:/Hybrid/64bit/vsfilters/SourceFilter/LSmashSource/vslsmashsource.dll")
# input color space: YUV420P8, bit depth: 8
# Loading F:\TestClips&Co\files\MPEG-4 H.264\TEST_delay-916ms.mkv using LWLibavSource
clip = core.lsmas.LWLibavSource(source="F:/TestClips&Co/files/MPEG-4 H.264/TEST_delay-916ms.mkv", format="YUV420P8", cache=0, fpsnum=24000, fpsden=1001, prefer_hw=1)
# making sure input color matrix is set as 709
clip = core.resize.Point(clip, matrix_in_s="709",range_s="limited")
# making sure frame rate is set to 23.976
clip = core.std.AssumeFPS(clip, fpsnum=24000, fpsden=1001)
# Setting color range to TV (limited) range.
clip = core.std.SetFrameProp(clip=clip, prop="_ColorRange", intval=1)
# adjusting output color from: YUV420P8 to YUV420P10 for x265Model (i420)
clip = core.resize.Bicubic(clip=clip, format=vs.YUV420P10, range_s="limited")
# Output
clip.set_output()

here,... iirc prefer_hw support was added back in November 2019 by HoyWu, his github is over at: https://github.com/HolyWu/L-SMASH-Works
(was added in: https://github.com/HolyWu/L-SMASH-Works/...13931b3f29)
damn, just noticed I used the VFR-mania sources to build L-SMASH in the Linux package. :/

But IMHO, in core.ffms2.Source, the right name of the track is not "vtrack", but "track" ?

Yes, that is a bug. -> will fix

Cu Selur