If I understand correctly, MKVs require an external SRT to avoid a full transcode (only transcode swap)? Or, is the full transcode entirely unavoidable with subtitle set to on?
>> If I understand correctly, MKVs require an external SRT to avoid a full transcode (only transcode container swap)?
Yep - if they are h264/aac or similar.
Must the SRT then be named exactly the same as the video file? Or simply placed in the same directory?
PMS has to be able to match it - so I guess it needs to have the same name + language + SRT extension.
Ok, thanks. I got the external SRT's to play nicely with MKVs and without the need for a full transcode by PMS thanks to the PlexConnect subtitle renderer.
Sadly, however, I'm experiencing the same "seek" issue first described back in Feb. in this topic. That is, when pausing or seeking (either direction), resuming of the video results in subtitles significantly out of sync. Playing with this further, this problem has nothing to do with the subtitles or most likely even the renderer. In fact, the subtitles appear exactly when they need to each and every time, perfectly in sync with the time stamp. However, the audio and video (after a resume) lag behind the time stamp as reported by the progress bar along the bottom of the screen. This video lag behind the time stamp progress bar even occurs when no subtitles are selected at all. The only way to bring the video to become in sync with the time stamps is to start the video from the very beginning.
So, this post probably doesn't even belong in this thread, as the problem seems to lie elsewhere.
I'm running the latest PMS and the latest PlexConnect. I tested 3 videos, all of which were MKVs (AVC plus DTS), and all exhibited the same resume problem, resulting in video resuming behind the time stamp.
Yep, known issue unfortunately. See also https://github.com/iBaa/PlexConnect/issues/242.
In discussion with Plex Inc right now... seems like they are already tweaking the transcoder. The issue might get solved with an upcoming PMS release.
Ah, hopefully Plex can get that fixed soon! Just one last question, and hopefully it helps someone else with subtitle difficulties. To avoid getting the PMS transcoder involved by converting the MKV to a native ATV format, I realize it needs an MP4 container and AVC video. But, what about the audio? It seems two audio tracks in the file are allowable (DD and AAC). What about DTS and AAC, as long as AAC is selected as the audio track, or would the DTS absolutely need to be stripped out? I'm just thinking what might be the easiest way to convert MKV to MP4.
Ah, hopefully Plex can get that fixed soon! Just one last question, and hopefully it helps someone else with subtitle difficulties. To avoid getting the PMS transcoder involved by converting the MKV to a native ATV format, I realize it needs an MP4 container and AVC video. But, what about the audio? It seems two audio tracks in the file are allowable (DD and AAC). What about DTS and AAC, as long as AAC is selected as the audio track, or would the DTS absolutely need to be stripped out? I'm just thinking what might be the easiest way to convert MKV to MP4.
Hi - in my experience with the MKV container DTS can be inside, but ATV can't play it natively. So if you select the DTS track, it will play, but PMS will transcode the audio. Not sure if DTS is even seen as a valid stream in MP4 containers.
PMS will not transcode if you have 5.1 AC3, as long as you select to "enable dolby on ATV" in PMS settings and turn the setting for Dolby output in the ATV itself to "on". This way, your 5.1 AC3 is passed through without intervention of PMS or ATV into your receiver.
So bottom line, you can have DTS in the file alongside AAC and AC3, but PMS will transcode when the DTS track is selected. When selecting AAC or AC3 (with above conditions configured) no transcoding will take place for the audio.
PMS will not transcode if you have 5.1 AC3, as long as you select to "enable dolby on ATV" in PMS settings and turn the setting for Dolby output in the ATV itself to "on". This way, your 5.1 AC3 is passed through without intervention of PMS or ATV into your receiver.
Right, but in the context of the topic, when you have a media with the MKV container with AppleTV compatible streams that don't require a transcode, PMS still needs to intervene in order to present an ATV appropriate container (MP4 or M4V). And, because of this, seeking in either direction during playback, causes the audio video streams to fall out of the right time stamp, and hence, the subtitles become out of sync.
I guess he answers more to your second question: "But, what about the audio? ..."
Found something interesting today: when using the "jump markers" (remote down, then right/left to jump through the progress bar)
- with MP4 the same marker will bring you to exactly the same scene/frame
- with MKV (transcoded to ts) aTV has issues finding the right spot - you will jump to "roughly" the right time, but +/-5 sec, basically the gap in the subtitle sync issue
- with other ts (tested with ABC.com media) aTV finds the correct spot as well, repeatably
Question: What is the difference between ABC's ts and Plex's ts? More timing data? Higher timing resolution? Anybody able to do a compare?
I found out something interesting as well. :) So, it appears you can indeed have subs displayed embedded in a file from PlexConnect without the need for the transcoder. But, they need to be in the right format and container. I use Xmedia Recode (I'm sure there others) to take the MKV and create a subtitle-embedded MP4. For video, I simply 'copy stream' and for audio, I copy audio if AC3 or re-encode to AC3 if DTS and select MP4 as container.
As for the subs, the software automatically recognizes that the embedded MKV srt needs to be converted to the MOV format, otherwise known as a tx3g subtitle. Then, in order to make them work during playback, you first need to begin playback, and only then long press on the select button, go to subtitles, and then select the language (not auto). Although the tx3g subtitle can be seen in the list of subtitles where you would normally select subtitles, it won't work to select it there. You need to select in the 2nd subtitle menu only accessible during playback.
Question: What is the difference between ABC's ts and Plex's ts? More timing data? Higher timing resolution? Anybody able to do a compare?
My guess is that the Plex ts contains a non-native audio format in DTS? Or, are they the same? In some of my testing, it's not just the container that creates out of sync subs, it's also the DTS --> AC3 conversion that screws something up.
>> subtitles embedded in aTV native media files
That's not that new...
see here: https://forums.plex.tv/topic/95057-official-new-subtitle-renderer-feedback-thread/?p=563652
>> sync issue caused by audio format?
The streams I tested were based on the same source file formats. But you are right, a "bad" audio format will trigger transcoding as well, so the final data will be shipped to aTV in a Plex generated TS...
Bottomline: as soon as we feed the aTV with Plex generated TS, it has issues finding the correct replay position, which causes a messy timing and subtitle sync issues.
Now I wonder, if this is related to the other two open issues as well:
- white progress bar, no fast-forward and such
- "error occured loading" right before the end of a show
Anyone know of a way to have the SRT announce its original title label before it was extracted? That is, its language and whether it's forced, commentary, or other such? Or, is this sort of info only available if packaged in a container?
SRT is just a text file, I don't know of any meta data hidden in there...
Just open it in your favorite text editor and have a look.
Does anyone know if there is an open ticket or official bug report to Plex for this issue where the time stamps go out of sync with transcoded media?
I talked to them... they is aware of this issue.
Seems the subtitle vs. audio/video lag could take a while to solve (it's been known for quite some time), but I recommend just using Plex on iOS and sending the video to Apple TV through Airplay in the meantime. I'm impressed by how stable this solution is, and although not quite as practical/easy as Plexconnect, it's certainly nice not get get aggravated by out of sync issues ... ;)
Seems the subtitle vs. audio/video lag could take a while to solve (it's been known for quite some time), but I recommend just using Plex on iOS and sending the video to Apple TV through Airplay in the meantime. I'm impressed by how stable this solution is, and although not quite as practical/easy as Plexconnect, it's certainly nice not get get aggravated by out of sync issues ... ;)
You can just disable PlexConnect's subtitle rendering and get the same effect without having to use AirPlay.
Seems the subtitle vs. audio/video lag could take a while to solve (it's been known for quite some time), but I recommend just using Plex on iOS and sending the video to Apple TV through Airplay in the meantime. I'm impressed by how stable this solution is, and although not quite as practical/easy as Plexconnect, it's certainly nice not get get aggravated by out of sync issues ... ;)
OK, but that doesn't have anything to do with the issue related to using non-apple standard video formats. If you are trying playback such a format with exterior subtitles, the subtitles will maintain the right time stamps whereas the video/audio streams, while in sync with each other, fall behind the time stamps of the subtitles. This isn't a problem if you choose to fully transcode the video on the fly, as the subtitles are burned into the transcode.
On the other hand, if you are using a standard apple video format, then there are no sync issues that I'm aware of, as there is no need to transcode on the fly. I'm not sure how using another apple device in the middle allows you to circumvent the above issue.
