Internal SRT subs not displaying with VC-1 videos

[fredflix 23]

I have a couple VC1 encoded MKVs with 1 embedded subtitle in SRT format.

Chrome and Firefox don't support VC1, so naturally Emby transcodes the video.
The transcoded video and audio play fine but the subtitles are not showing even though it's already selected.
While the video is playing, if I switch back and forth between the English sub and None, still the same, the sub just doesn't get rendered.

 

Here are the scenarios I've tried (please note: videos are streamed on a Linux PC from a local linux server serving Emby via docker, 1Gbps LAN):

Home network quality set to: 1080p - 60 Mbps
- VC1 video with SRT sub => Transcoding and no sub rendered

- VC1 video with PGS sub => Transcoding and sub is rendered

- H264 video with SRT sub => Direct Stream and sub is rendered

- H264 video with PGS sub => Direct Stream and sub is rendered

 

Home network quality set to: 720p - 2 Mbps (to force a transcode)
- VC1 video with SRT sub => Transcoding and no sub rendered

- VC1 video with PGS sub => Transcoding and sub is rendered

- H264 video with SRT sub => Transcoding and sub is rendered

- H264 video with PGS sub => Transcoding and sub is rendered

 

From looking at the log (which I've attached), the stream mapping looks weird:

22:09:18.275 Stream mapping:
22:09:18.275   Stream #0:0 -> #0:0 (vc1 (native) -> h264 (libx264))
22:09:18.275   Stream #0:1 -> #0:1 (truehd (native) -> mp3 (libmp3lame))
22:09:18.275   Stream #0:2 -> #1:0 (subrip (srt) -> webvtt (native))
22:09:18.275   Stream #0:0 -> #1:1 (copy)

Specifically the last line. I'm not sure which track it's trying to copy since the video, audio and sub track all have to be re-encoded.
I've also attached a "mediainfo -f my_video.mkv".

 

I know this is the web app section but the same problem occurs on my Nvidia Shield 2015 using the Emby app.

On the other hand, the Emby app on my Android 9 phone plays the VC1 videos with the SRT subs no problem. It actually direct plays them all.

vc1.log

mediainfo.txt

[Luke 37129]

Hi, @@fredflix, there's a good chance this will be improved with the upcoming 4.4 server release. Thanks for reporting.