Server Version#: 1.29.2.6364 (Ubuntu)
Player Version#: 9.12.1.36893 (Google TV )
Tuner Make/Model: HDHomeRun Flex 4k
Guide/Lineup name: Local Broadcast listings (zip: 92808)
Using XMLTV?: no
Channel number/Name: n/a
I’m streaming Live TV (MPEG2 via an ATSC 1.0 broadcast) to a TCL Google TV within my home network, set to stream at original/maximum quality in the Plex client app.
It works fine. No problems.
When I enable captions, my Plex server starts transcoding and can’t keep up, so the video plays a bit, then pauses, then plays a bit, then pauses. The reason given for the transcode: “The selected subtitles require transcoding to maintain their appearance”
So okay, maybe my Plex server’s not strong enough, however CPU usage never goes above 25% while transcoding. It’s running on an Ubuntu machine with Intel QuickSync (Intel J5005 Gemini Lake) which has been great at transcoding any kind of content I’ve ever thrown at it - just not this.
If I quit Plex and switch over to the HDHomeRun Android app on the same TV, the video plays fine with or without captions enabled. There’s no stuttering at all. So it seems the client device, this TV, is capable of processing native subtitles, but maybe the Plex client doesn’t know that.
So my question is… What’s going on here? In both cases I’m streaming the exact same MPEG2 stream (I believe, right?) with captions to the same TV. When I do it with subtitles via Plex, it transcodes. When I do it with subtitles via HDHR, it doesn’t.
Audio and subs are a single threaded process to keep it in sync with video hence the 25%.
Are you sure the HW is doing the video part? That processor is a little weak for Plex. Need something with a higher Single Thread Rating and it seems with each OS and Plex version it goes up.
Captions Disabled:
“Video: 720p (MPEG2VIDEO)
→ Direct Stream
Audio: English (AC3 Stereo)
→ Direct Stream”
Captions Enabled:
“Video: 720p (MPEG2VIDEO) (hw)
→ 720P (H264) – Transcode (hw)
Audio: English (AC3 Stereo)
→ Direct Stream”
(I’d upload an image but the forum errors out when I try.)
What I’m trying to figure out is why Plex is choosing to transcode at all. What does the HDHomeRun app do differently on Android/Google TV that allows this to work?
What I see happening on a live stream is the subs are burned in so Plex runs it through the transcoder to extract the text and then re-encode to the client default of H264. So this seems driven by the capabilities of the Plex client.
The HDHR client has the ability to extract the sub locally.
I just disabled “use hardware acceleration when available” in the Plex server’s transcoder settings and that somehow fixes the problem.
Captions disabled = direct stream
Captions enabled = still transcoding, but without pauses
That tells me that CPU transcoding is somehow more performant than Intel QuickSync on this thing, but that can’t be right…and I’m still not sure why it’s transcoding at all.
I think the reason is, the CCwGTV doesn’t actually support Closed Captions. Closed Captions are actually embedded as part of the video stream, so Plex has to extract them and make them a subtitle format that the CCwGTV does support or burn them. But don’t quote me on that, I don’t actually know for sure and may be speaking out my ass here.
