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NVidia Shield: SRT subtitles causing "burn subtitles" to activate when audio is also transcoded

sethgregorysethgregory Posts: 21Members, Plex Pass Plex Pass

Hi all,

I'd just written a lengthy post wondering why some media was transcoding instead of direct-streaming when there seemed to be no good reason why it should - when I realized that in my Tautulli logs it noted that the subtitles were being burned (despite being .srt subs, not an image format.)

"But that can't be," I thought to myself, "because some of my media direct plays just fine, and I always have subtitles enabled!" After some more digging through logs, I realized that this is only happening on media that has EAC3 audio streams, which incurs an audio transcode (since my sound bar is connected via optical audio, which doesn't support EAC3.) When it's AC3? Plays fine. DCA? Plays fine.

This seems like a bug! Are others experiencing the same? Can we expect a fix?

Thanks much!

Comments

  • rwofficerwoffice Posts: 197Members, Plex Pass Plex Pass
    edited April 24

    I've noticed a similar behavior, but haven't been able to pin it down as specifically as it sounds like you have. All I know is sometimes SRT subs require transcoding, and sometimes they don't. I'll start checking the corresponding audio codecs and see if that shows a pattern.

    Right off the bat I can tell you that the last few shows that had forced SRT subs that required transcoding were all EAC3. I'm watching a show right now that's AAC audio and when I enable SRT subs it still Direct Plays with no transcoding. Both of those initial pieces of evidence seem to line up with what you were saying.

  • sethgregorysethgregory Posts: 21Members, Plex Pass Plex Pass

    Yeah, sounds like the same issue. This is problematic for me because more and more content has EAC3 audio streams, and my PMS is running on a somewhat underpowered Synology NAS. I just picked up a Shield because I heard such great things, and by and large the experience has been great, but this seems like a big negative...

  • Dion250Dion250 Posts: 210Members, Plex Pass Plex Pass

    Plex burned text based subtitles into the video cause they were going out of sync in HLS. But that was fixed in ExoPlayer v2. They should never be burned now that the Android App is based on ExoPlayer v2.. So it's probably a bug. But lets face it.. Plex fixing bugs on the Android Client? LOL gl with that.

  • sethgregorysethgregory Posts: 21Members, Plex Pass Plex Pass

    Depressing response. Seems like it should be a straightforward fix, and one that improves quality of life for a relatively large population of users... :/

  • rwofficerwoffice Posts: 197Members, Plex Pass Plex Pass

    This is happening a lot, so I thought maybe I could bump this and they can try and get to the bottom of it.

    tl;dr: If for any reason the audio needs to be transcoded then the subs are burned in, causing the video to be transcoded as well, even for files where direct play of the subs works when the audio is not transcoded.

    As an example, see this image:

    On the left is AC3 5.1 and on the right is AC3 2.0. All I did was start the file and then change the audio track from 5.1 to 2.0 and, as you can clearly see, everything Direct Plays just fine with AC3 2.0, including the forced subtitles, but requires complete transcoding with AC3 5.1, because it has to burn the subs.

    That's a huge amount of resources being used up just because the audio needs to be transcoded.

    I'm also attaching the client logs where you can see the MediaDecisionEngine clearly say in regards to the AC3 5.1 stream:

    Unable to direct play; AC-3 audio is not supported by the device

    Even though 14 seconds later it decides AC-3 2.0 is just fine.

    Regardless, I don't care if it's transcoding the audio stream, what I do care about is that consequently if the audio needs transcoding then it's also transcoding the video stream in order to burn in the subtitles, which is completely unnecessary as they direct play just fine when the audio doesn't need transcoding.

    I hope I've explained this clearly enough. If the devs have any questions, or want me to do more tests or provide more info, don't hesitate to ask. I'm happy to provide a video sample if a dev responds and asks for it.

    Client: Nvidia Shield
    Plex Version: 6.16.2.4628
    PMS: Windows 10 1.12.1.4885
    Setup: Shield direct via HDMI to Stereo Samsung TV, no audio receiver/etc.
    File Information: See Attached MediaInfo

  • sethgregorysethgregory Posts: 21Members, Plex Pass Plex Pass
    edited May 17

    After searching a bit, there are actually quite a few threads detailing the same issue. This is a widespread problem, and one that seems fairly easy to pinpoint if what Dion250 said is correct, and this is a remnant of a prior fix for an ExoPlayer v1 issue. It's a critical bug in the transcoder, essentially making my ShieldTV (and apparently any Android client) useless for those of us who use subtitles by default, and I'd honestly prefer not to have to switch to Kodi with the Plex plugin - that's really not an ideal solution.

    Would really love at least a response from Plex on this...

  • rwofficerwoffice Posts: 197Members, Plex Pass Plex Pass

    According to a post in another thread, the beta release of 6.18 addresses this issue, so hopefully it gets released soon.

  • mtappertmtappert Posts: 72Members, Plex Pass Plex Pass

    @rwoffice Can you link to that thread? Subtitles on the Android app are a complete disaster since the switch to ExoPlayer v2. The only way I can get my .srt to show up is by choosing always burn in.. it's driving me insane!

  • Dion250Dion250 Posts: 210Members, Plex Pass Plex Pass

    @mtappert said:
    @rwoffice Can you link to that thread? Subtitles on the Android app are a complete disaster since the switch to ExoPlayer v2. The only way I can get my .srt to show up is by choosing always burn in.. it's driving me insane!

    It shouldn't be burning subtitles just cause audio is transcoding now with ExoPlayer 2. Only the devs can help you at this point. You will be waiting awhile im afraid or convert all your EAC3 to AC3.

  • rwofficerwoffice Posts: 197Members, Plex Pass Plex Pass

    @mtappert said:
    @rwoffice Can you link to that thread? Subtitles on the Android app are a complete disaster since the switch to ExoPlayer v2. The only way I can get my .srt to show up is by choosing always burn in.. it's driving me insane!

    Now that I'm re-reading it, it might not be exactly right, but here you go anyway:

    @mmhorda said:
    6.18 version finally doesn't force transcoding with turned on subtitles but still buffering on Sony Android TV. Works perfectly on SHILED with HDR and high bitrate videos, no buffering.

    https://forums.plex.tv/discussion/comment/1668505/#Comment_1668505

    Fingers crossed it's true, since the burning subs just because you're transcoding audio thing is super annoying :)

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