[oldpoem]

It works.

result mediaconfig.xml

Code:

<rule filetypes="mkv" videocodec="hevc">
            <source filter="lavfsplitter" />
            <splitter filter="lavf_splitter" />
            <video filter="lentoid_hevc_decoder" />
            <audio filter="lavaudiodec" />
            <subs filter="xyvsfilter" />
            <extra>
                <extra filter="ffdshow_audio_processor" />
            </extra>
        </rule>
        <rule filetypes="mkv">
            <source filter="lavfsplitter" />
            <splitter filter="lavf_splitter" />
            <video filter="lavvideodec" />
            <audio filter="lavaudiodec" />
            <subs filter="xyvsfilter" />
            <extra>
                <extra filter="ffdshow_audio_processor" />
            </extra>
        </rule>

Also I have a suggestion. Since order is important in this case, could you implement something like moving rules up/down in GUI ?