MKVs from seamless branching blu-rays cause atmos audio drop outs and/or sync loss #10520
Comments
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Just stumbled across this with apocalypse now seamless branch, kodi seems to handle it fine, finding alot of issues on reddit dating back a few years from various movies having this issue, is there any progress on this issue? Kodi seems to have this fixed, but seeing more reports on this issues for things like plex that use exo player as titles that use seamless branching with 4k atmos continue to grow.. |
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any news from this? |
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It would be great if this could be fixed. It seems all the players on android that support Dolby Vision are based on ExoPlayer, so there is currently no way to play problematic Dolby Vision titles with seamless branching without TrueHD issues. Using domyd's MLP demuxer does help, but even that cannot fix some 2 in 1 discs for ExoPlayer. VLC plays the problematic files with no issues, but it doesn't support Dolby vision. |
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@christosts can you please take a look? |
Thanks @rohitjoins, @christosts if you need any help with logs or testing etc, then I'm happy to help |
@Montell-S, domyd's MLP demuxer will fix this title, there is a bit of technique to getting it right though. I can share the method I use if you're interested. The latest nightly version of kodi now supports Dolby Vision in MKV, so I use that for the problematic titles. |
I took a look at the tool and also related discussions at the mentioned plex/reddit forum, plus the kodi code fixes. I'm not an expert on blu-ray, and please correct me if I'm wrong, but my understanding that existing tools the convert blu-ray to MKVs copy the audio from the disc on the mkv, including the overlapping audio frames at branch boundaries (as described in https://github.com/domyd/mlp). Therefore, the resulting mkv file has overlapping audio frames. If that is so, this is an issue that we'd classify as "malformed media" rather than a spec-compliant piece of media, and we don't plan to alter the player to address this. Please do let me know if my understanding about the root cause of the problem is different. |
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@christosts Someone with more technical knowledge would need to help explain it,, but this is a disappointing result. These are commercial media discs, xbox's, blu ray discs players all need to handle this type of seamless branching audio. As mentioned the title you quoted from someone else was not a great solution considering it plays fine in kodi without using some obscure third party demuxer, and again plays fine in a commercial player. We are seeing alot of these issues pop up in plex forums and people complaining about stuttering audio falling out of sync and not knowing what causes it. Only a few went down the rabbit hole and ended up here. If we cant get a solution many of us will have to stop using plex and exo player which would be disappointing and moving to a branch like kodi. |
From ExoPlayer's perspective this is irrelevant. We are only concerned with the MKV you're asking us to play, not where it was originally converted from. If the MKV is not valid, then the issue should be reported to the owners of the tool that produced it. |
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@icbaker they have, players have had issues with these discs and offered fixes through firmware updates. I think this is becoming clear exo player is not going to address this, many of us with plex will have to talk to them or find other options. |
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Hello christosts, With respect, I don't think that's an accurate evaluation of this issue. You cite https://github.com/domyd/mlp as describing the phenomenon. Perhaps because it has been claimed that the application there "fixes" a problematic title? Yet the author of that application states that "MakeMKV 1.15.4 and newer uses the same method for joining TrueHD streams, and should produce flawless TrueHD streams as well." The vast majority of the people experiencing this issue are using MakeMKV to generate the affected MKV files. |
Yet, according to what chrisosts posted, he hasn't played any MKV files or analyzed them himself. Rather, he has inferred, from reading about what a tool someone suggested does, that the issue with all cited MKVs must be (that they are "malformed" despite the most popular tool for generating them conforming to what has just been cited as best practice). And based upon that, closed the ticket. There has been no indication that exoplayer contributors have investigated the issue beyond doing some reading last night, after letting the report languish for months. And now. . . ticket closed. |
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I don't know if anyone is going to bother reading this at all now since this ticket is closed, and I don't really know what to say to you, or whether it is your code that is wrong or MKV file format that is wrong somehow (but if the file format is wrong then why does it play back perfectly in all other players including PC based players without audio problems?) As HurinSteadfast said on PLEX forum: "While I hate to let plex off the hook for this, I think I have determined that this is an issue with the exoplayer (by Google) embedded in the Plex client rather than a problem with the Plex client or code itself. Why? Well, I tried jellyfin to work around this issue, and found that the exact same issue at the exact same place occurred in The Martian (and some other movies I have). However, jellyfin allows you to change the embedded player from exoplayer to libVLC. . . and upon trying libVLC, the problem disappears. So, since both jellyfin and plex use exoplayer, and both are affected (yet jellyfin ceases to be affected when exoplayer is disabled), I believe that indicates Google’s exoplayer is likely the culprit. " I have got this problem on multiple discs now and latest and worst I have found is the Extended Cut of M3gan on Bluray. My post on PLEX details it and also shows the MakeMKV log which it generates while reading the disc to produce the MKV If you need me to send you the entire original M3gan MKV file to attempt playback and test / investigate I can - the audio dropouts occur at least 10 times throughout movie after the first one about 35 minutes in (when she kills dog) |
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Please note that the ticket has been re-opened. So, let's all stay chill. :) |
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@geogan try DGDemux, if that doesn't work, then I have another method that will work. https://www.rationalqm.us/dgdemux/binaries/DGDemux_1.0.0.67.zip |
This program only extracts and de-muxxes from original full disc image copies (ie exact Bluray/4K disc images with entire original structure). This is not what we are getting from MakeMKV - that already does all that job of extracting/muxxing from original file structure on disc and producing a final muxed MKV file with just the video/audio track and subtitles only. So no use here. We are not really looking for alternate Bluray ripping program solutions here. This is just confusing things. Are you saying Exoplayer uses some buggy demuxer? (domyd's MLP demuxer)? |
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@geogan, it's pretty simple to drop the output from DGDemux into MKVToolNix to produce your MKV. MakeMKV uses domyd's MLP demuxer but it does have issues. I use a slightly different method and it works 99% of the time, but ExoPlayer does need fixing, because it doesn't happen with any other players. |
Yes but DGDemux only works with full disc decrypted disc images, which is not what we have here. You are basically suggesting a complete alternative to MakeMKV. I don't have any interest in re-ripping using alternate complicated methods (yes I do know and have MKVToolNix for other uses for years). OK, so MakeMKV uses domyd's MLP demuxer, right. Well there is definitely a problem somewhere between this MLP demuxer (which MakeMKV apparently uses) and Exoplayer reading what it produces. I'll just repeat what I said on PLEX here in case its not read by devs: But anyway I just tried playing back the M3gan MKV locally on my Windows 10 PC from the server on some local players… KMPlayer 2021.02.23.57 SMPlayer 22.7.0 rev10091 VLC Player 3.0.18 Vetinari Windows Media Player 12.0.19041.2788 All were able to get past the first problem point at dog attack around 35mins without audio dropouts. The only program that went out of sync a bit was Windows Media Player when I tried to seek up to just before problem, but when I went back to start and then seeked to a bit further back there was no problem. |
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@geogan, unless you can find a player that can deal with the output from MakeMKV, then you have no choice but to re-rip. It's not complicated. |
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@dastardo, as you just put it, "unless we can find a player that can deal with the output from MakeMKV". . . Kodi was apparently modified so that it can play back the cited mkvs without issue (which I intend to test with renewed urgency). Is it your contention that there is no issue with exoplayer and that the fault lies entirely in "malformed" MKVs? If so, fair enough, nobody can stop you from making that case. However, I'm not sure it's possible, from (y)our vantage point, to determine which demuxer/transcoder/ripper is doing things correctly vs which ones are simply doing things in such a way that it doesn't happen to trigger this unfortunate behavior in exoplayer. If that is not your contention, and you allow for the possibility that exoplayer needs to be improved so that it can play back MKVs ripped from seamless branching blu-rays without issue, may I kindly invite you to join us on the Plex forums where I'm sure many of us would welcome any guides you would like to post to help us work around the issue (ie., rip our blu-rays in such a way that does not trigger this issue) while the investigation over here continues. It doesn't seem like this is the proper venue to work around the issue on a disc-by-disc basis using multiple different de/remuxers. And I'm not sure it's helpful in determining whether the issue is with exoplayer itself or with media that we're told has been demonstrably mangled. |
Well I did just list four players above which can deal with the output from MakeMKV... but I presume you mean on NVidia Shield or that PLEX on Shield can use instead of Exoplayer |
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@HurinSteadfast The issue is with ExoPlayer, but there are some problematic discs. The best example of this is the 2 in 1 UHD of Resident Evil: Apocolypse. domyd does give a good description of what his demuxing tool does. He does explain in quite a lot of detail at https://github.com/domyd/mlp The problem is, it needs more development, but I don't think he's working on it anymore. @geogan try the Resident Evil: Apocalypse 2 in 1 UHD. The only way I can get it to play without dropouts and going out of sync is to demux the audio with DGDemux and then play with Kodi. |
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Interesting FAQ there on the domyd github about removing the duplicate end frame. But I doubt that is anything to do with our problem. But interesting he mentions this "major sync" thing... "we can cut the very last TrueHD frame off a stream without consequences. The reason for that is that the start of every stream always has what's called a major sync. Major syncs are basically restart points for the decoder, where any issues introduced by previous audio data are no longer relevant" Maybe that's the thing that is switching audio format at branch point and should be fixed to have correct lossless format in it? Also, I used MakeMKV v1.17.3 to rip the M3gan Bluray and that is still completely riddled with at least 10 audio dropouts/out of sync continuations... so the switch to this better demuxer doesn't appear to have fixed or affected problem. |
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domyd's demuxer does have some issues, unfortunately, it looks like he's not developing it anymore. The latest Nexus build of Kodi will playback without any issues if you want Dolby Vision, or you can use VLC if you're not bothered about Dolby Vision. |
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Not sure if the observations will be helpful but here goes. All these observations are based on known seamless branching "problematic" blu rays (in my case known examples are The Natural, F9, the Martian, BlackHawk Down).
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Thank you for these contributions here and elsewhere, scarbrtj! On another note. I found this interesting (maybe I won't be the only one): I was doing some googling and was surprised to find a lot of reports of "audio dropouts" related to "seamless branching" with TrueHD/Atmos on older blu-ray disc table-top players as well. Around 2014, the industry addressed the issues in their newer batches of disc players and everyone moved on. https://www.audioholics.com/news/dolby-atmos-old-blu-ray-players So while it's true, as we've been told, that TrueHD/Atmos is primarily seen on discs (blu-ray), even disc players didn't handle seamless branch transitions correctly for TrueHD/Atmos and needed substantial fixes. Substantial enough to require new hardware (not just firmware) revisions. |
Strong bet that somehow the guts of Exoplayer use the playback behavior and/or "code" of the old, pre-seamless branching blu ray players. This gives hope that Exoplayer could make seamless branching really and truly work imho. There's gotta be a way. Now there just needs to be a will. |
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If you search this issue on certain blu rays pretty sure alot of hardware players come up even recently on 4k blu rays that had to issue firmware updates to fix this. I just cant say I agree with the exoplayer devs stance on this. I do know the shield had an issue recently (few years back) where the atmos bitrate (Im going from memory 3 years ago) would go beyond the truehd spec and drop out or the frames were to large, MAT spec was also not well documented. But yet the issue was still fixed..... This occurred on hardware players and software players. There were posts on the shield forum and it eventually got fixed. I still dont know how this issue is any different. A blu ray is just folders with mt2s files and I think we established that has issues as well. Remuxing into an mkv is beside the point and is not contributing to the issue at all.... Maybe were better off posting on the shield forum like many did with the shield atmos dropout which eventually got attention and resolved (gurardians of the galaxy 2 had a number of dropouts) which was a problem a few years ago. See below link. |
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Btw just for proof this affects hardware players, I believe microsoft fixed it on xbox blu ray players, but the ones we know about like black hawk down microsoft looked into it and as far as I know eventually did fix this bug. |
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Once again, thank you for your engagement on this issue. With respect, two out of three of the major bullet points in your last post were predicated upon this issue being related to the media being file-based rather than blu-ray based. Does (should?) your analysis change now that there's multiple articles of evidence that blu-ray players needed modification/adjustement/fixes (beyond firmware level, in some cases) to accommodate TrueHD/Atmos on seamless branching discs? To be fair, I can see --from a strict "you can't prove anything about exoplayer with this sort of evidence" perspective-- how you might not find this compelling. Granted, lacking specs and dev experience in this area, we are inferring certain things from circumstantial evidence. Such is the fate of laypeople trying to determine the root cause of an issue from the outside. And, also granted, the file-based media is pre-generated at the time the blu-ray is ripped. While, on the blu-ray player, the stream is generated dynamically. Yet, still, it seems like the same processes happen in each case (concatenating the audio streams) and even physical disc blu-ray players dealt with this (or very similar) issue years ago. Perhaps the specs and documentation for handling this on blu-ray would therefore be helpful here. We're just laypeople and users so we can't direct you to such things. But surely, someone on the exoplayer team has the access and expertise? Thank you for considering! --H |
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And on his complaint there is no spec's, if he wants to check that link I posted a few posts up he will see that it was eventually fixed by exoplayer dev's, but one common comment you will see as I followed that bug back in 2018 was that dolby MAT spec's were not well documented, its just the nature of the beast. But that did not stop the dev's at the time from fixing an issue playing retail commercial disc's back properly without dropouts. |
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**"With respect, two out of three of the major bullet points in your last post were predicated upon this issue being related to the media being file-based rather than blu-ray based." "A blu ray is just folders with mt2s files and I think we established that has issues as well. Remuxing into an mkv is beside the point and is not contributing to the issue at all...."**
Interesting: |
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Note in the above: Plex used to "use our own implementation of True HD passthrough". . . rather than relying on exoplayer's. Could they not do so again to potentially work around this issue? |
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Software problem, somewhere, probably? https://forums.plex.tv/t/nvidia-shield-dolby-truehd-playback-is-borked/778375/287 |
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Thank you scarbrtj. To quote what's at your first link:
More and more, it seems like we're a tweak away from having this fixed. Blu-ray players had to do it. Software players had to do it. Perhaps exoplayer needs to do it. @icbaker, is this having any effect? 🤞 P.S. There's more at the links! |
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DGDemux team member states: "DGDemux makes a clean single-file rip, correcting for the M2TS gaps. There should be no problem playing it after remuxing to MKV. I've done it many times. There simply are no gaps remaining after this process." . . . and yet, exoplayer. . . and only exoplayer. . . chokes on it. |
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Yet another player modified their code because it couldn't correctly playback TrueHD/Atmos on seamlessly branching discs. Honestly, it seems like just about any player you stumble across has something like this in its change log. That is, except exoplayer. https://github.com/Nevcairiel/LAVFilters/releases/tag/0.75 "Fixed: Resolved an issue with glitching TrueHD bitstreaming on seamless-branching titles" @icbaker, please reconsider. Given all the software players and hardware (disc) players that have had to modify their code to playback TrueHD/Atmos from seamlessly branching discs, it seems more and more evident that most (if not all) media players needed to adapt to changing/advancing technology (in this case, atmos combined with seamless branching) in order to provide their users with a satisfactory experience. There is no evidence that there is anything wrong with the discs, nor the MKV files being extracted from them. But there is ever-mounting evidence that media players needed to be tweaked a while back to properly handle TrueHD/Atmos and seamless branching. . . and exoplayer never implemented those tweaks. Please, reconsider and put the experience of exoplayer users ahead of whatever principle is precluding the exoplayer team from taking this seriously and fully investigating. (hat tip to ghostm over on plex forums for pointing out the LAV Filter change) |
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Just chiming in that I've noticed this issue with Apocalypse Now on the Shield (which I have learned uses Exoplayer). My Dune HD Real Vision 4K played the same file with no issues. |
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still no fix :( |
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If you have say two discs comprising one movie, for example part 1 (disc 1) and part 2 (disc 2) of Zack Synder's Justice League, Plex suggests merging the two files together: "However, to get a better overall experience, we encourage you to instead use a tool to join/merge the individual files into a single video. There are multiple ways you can do this and a quick search in your favorite search engine should give you some options on how to “join” files. An unofficial guide with one free tool has even been posted in our forums." But DO NOT do this (like with MKVToolNix for example). You will create a seamless branch point, and the audio will go out of sync at the branch point (if bitstreaming back on Shield... all other players will be fine, and it will be fine on Shield if you transcode the audio). You MUST name as pt1 and pt2 to keep from going out of sync. |
In my testing (using LOTR 1 remaster) both the Shield and my Dune HD Real Vision 4K had the same issue. The only player I know of that doesn't is my Zidoo Z9X Pro. The Dune HD plays seamless branched disc remuxes fine, but has issues if you edit the tracks yourself. |
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Rudy 4K: seamless branched, has audio sync issue with Atmos on Plex with Shield |
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same issue here, still no fix |
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It's just astounding to me that the exoplayer team's stance has come down to: Even though every other player has figured out how to play back these files properly, we won't do so. Because nobody asking for it can tell us how to do it. And we aren't willing to do the research and work ourselves. to figure it out. We're customers. Not developers. There has been ample evidence provided that other players have noted this issue and addressed it. But exoplayer will not. |
@icbaker already explained above (#10520 (comment)) why we can't easily fix this issue. It mostly comes down to having no known spec of how Dolby True HD is supposed to be packaged in MKV (or another container). But we are still happy to accept pull requests that provide a fix with some explanation for why that is a suitable way of fixing the issue.
I can understand your frustration that there is no simple, quick fix available for the problem you face, but please note that ExoPlayer is an open-source project and there are no customers as such. And this is also not a customer service :). We maintain the project, accept contributions from external developers and discuss and solve technical issues with those developers (who are directly using the library in their code). If you feel like you are a (potentially paying?) customer of Plex, then it's probably best to reach out to them to highlight your technical issues. They are likely better placed to either work around it in their app or provide us with the pull request or additional context we are missing to make progress. |
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"MK4" |
And yet, the container type has never been the issue. Nor is the issue that these are "file-based" media derived from discs as @icbaker assumed/asserted since the beginning. As has been demonstrated, and said repeatedly, exoplayer fails to correctly playback seamlessly branched TrueHD+Atmos media regardless of container or media type. Indeed, one suspects that if we could rig a disc up directly to exoplayer, we'd see the issue there too. There are several examples politely and patiently documented above of hardware and software media players discovering and fixing the same apparent problem. To quote one of the examples: "Fixed: Resolved an issue with glitching TrueHD bitstreaming on seamless-branching titles" Here's another: "Allow TrueHD frame times to be a lot bigger. On seamless branching points, there can be a huge frame time gap, which seems to be expected, so just allow it for now."
Apologies. I mispoke and was writing in haste. My feeling being that longer, more polite, accurate, and detailed responses didn't seem to be productive either. I meant to say "user." But, the clarification is noted. Incidentally, the link to the long and detailed plex thread is in my initial report (it even includes some posts from Plex personnel). If we can't get plex to contact you, how do we cajole you into contacting them to "discuss and solve technical issues with those developers?" If I seem less cordial than usual (while still remaining civil, always!), it's because I feel that, from the get-go, there has been scapegoating and excuse-making for why nobody should really look into this. Everyone is at great pains to explain why it's not their problem. And now, how we're not "customers" (etc.), but nobody is willing to go to any pains to actually be productive towards resolving the issue. I too work in an industry where we often have ample means and reasons to tell our users (or customers) why something isn't our responsibility to fix. Yet this would often leave our users/customers stuck with nobody who can really help them. Thankfully, usually one of us is curious enough, or kind enough, or conscientious enough to help regardless. And we try do that where we can. But, again, your clarification is noted. We are not "customers" of your "product". . . we're just "users" of your "project" because a product we purchased makes use of it. We can't make Plex contact you. And we can't make you contact Plex. So. . . from the exoplayer team's perspective, there's nothing to be done here. And yet something tells me the Plex people would tell us that they use the exoplayer application because it's supposed to function correctly. So if it's not, "that's an exoplayer problem and it's not Plex's job to change exoplayer." Joy. --H |
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New Conan the Barbarian 4K has the audio issue |
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Step Brothers 4K has the audio issue |
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The Abyss 4K has the issue... severely! |
ExoPlayer Version
2.18.1
Devices that reproduce the issue
NVIDIA Shield Pro w/ SHIELD Android TV v9.1.0(33.2.0.125)
Devices that do not reproduce the issue
Reproducible in the demo app?
Not tested
Reproduction steps
Expected result
Audio plays back normally.
Actual result
Audio momentarily drops out (goes silent) and then returns out of sync with the video when a "seamless branch" boundary is crossed. Occasionally, the audio merely drops out but remains in sync upon return.
Media
Geogan on the plex forums has provided/extracted a clip that reportedly exhibits the issue: https://forums.plex.tv/t/plex-audio-dropouts-and-sync-issues-with-seamless-branching-on-4k-truehd-atmos-movies/775510/24
Alternatively, the full MKV extracted from 4K UHD Blu-ray of "The Martian" could be used. The audio will drop out and/or go out of sync on the extended edition wherever there is a "seamless branch" between the two versions of the movie. Example glitch is at 36:20 of Extended/Director's Edition where he says "I'm going to need to science the s--t out of this. . ." Which is the glitch provided in Geogan's clip linked above.
Bug Report
adb bugreportto dev.exoplayer@gmail.com after filing this issue.The text was updated successfully, but these errors were encountered: