ATMOS Audio Drop Outs - Details thread


#1

I thought I’d start a thread on this as it is apparent that a few Discs Suffer this issue. From what we know so far:

  • It only impacts the ATMOS Track when bit-streaming the audio
  • The audio drop out can last from a short break to a full 10sec of no audio (depending on how quickly your HW Equipment takes to resync)
  • The original Disc in a HW Player does not exhibit this issue (eg for me an XBOX One S plays it correctly).
  • The original Disc also plays fine using PDVD
  • It seems to impact players that use ffmpeg (eg JRiver Media Center, MPC-HC)
  • NVidia Shield also has the same issue (does Shield use ffmpeg?)

We don’t know for sure what the root cause but so far the summary of the speculation is:

  • Decryption Issue with DeUHD : Possible. In my testing comparing the output between DeUHD / makeMKV / AnyDVD each were writing different headers in the M2TS packets (though MakeMKV have confirmed they will update their prog to write the packets with the same values as discussed here3). Maybe it is such an issue at these points
  • Mastering Issue : Unlikely. We can all play these discs with dropping the audio on HW players.
  • PC based SW Issues : Possible. We are all using the same underlying ffmpeg dll for bitstreaming the Audio. ATMOS support is pretty new on the PC. Given that there is no issue with HW players, it could be a “bug” in ffmpeg handling these streams at this point (if you google ATMOS Dropout you get plenty of recent hits and bugfixes).
  • PC based HW / Cable Issues handling “High Bit Rate Atmos” : Unlikely. We all have different HW setups but each have the same issue at the same spot.

Sample: Here is a [URL=“https://ufile.io/kjezf”]40 sec sample[/URL] from a UHD BD with Atmos Track (325MB) where at the 33sec mark the ATMOS track drops out when bitstreaming to an AVR. This can be used for testing to see if your setup has the issue OR if anyone has the skills then please update us. I’ve also posted this in the LAV Forum on Doom9 in the hope the Hendrik/Nevcairel has some comments.

I thought it would be good to consolidate the details below of what Discs (and setups) are impacted.


#2

DISC: “Pirates of the Caribbean - Dean Men Tell No Tales” : ATMOS tack dropping out a couple of times between 17:45 and 19:00 minutes into the movie

SETUP: Tested on

  • SW Player: JRiver Media Center running latest LAV Nightly
  • AVR: Yamaha RX-A3060 with latest Firmware (Dec)

Symptom: The AVR drops the Audio, and the Front Panels goes from displaying ATMOS to “Decoder Off”. It takes about 10sec for it to start decoding Audio again.


#3

DISC: “Guardians of the Galaxy Vol II” : ATMOS track dropping out in multiple places in the movie (don’t have the time codes at this point).


#4

The most interesting correlation here is that both of the offending discs are Disney and both of the discs have a peak Atmos bitrate of 11.3mbps. Higher than what we have seen on standard blu.

Cars 3 (another Disney disc) has an Atmos track with a peak bitrate of just under 7mbps and I heard no dropouts with that rip.

The plot thickens…


#5

Yeah - there is also something “different” at these particular spots on the disc that causes the audio to stop bit-streaming (my AVR is getting nothing at these points) … but only with certain SW Players. I’m hoping it is something like a bug in ffdshow dealing with peak bitrate at these points? or some header difference?

Would like to see a VUK for either of these discs so we can compare.


#6

Well, hopefully now that Konsts has proven that he/she can provide MKB v61 based VUK keys we might see those titles soon. Will make for an interesting comparison.


#7

FYI - on a 5.1 setup the drop is brief, on my 7.2.4 setup it is a full 10 sec without sound


#8

I think it is dependent on the equipment. I am running a 5.2.4 setup and when the sound drops it is for a second tops. I am using a Yamaha RX-A3050.


#9

I’m guessing it is the long sync time on my PJ (X7500) with the 7.2.4 setup vs the LG OLED on the 5.1 as both have the same AVR (A3060). I also notice I don’t get the ATMOS decoder info on the 5.1 setup, which I guess is that I only have 5.1


#10

Without a doubt it is the projector causing slow resyncing. My Sony 600ES was pretty slow to sync as well vs my X940C.


#11

let me know where in GoG II you hear the first dropout.

i havent had time recently to watch the entire movie but i did have a single dropout towards the beginning when they are being chased and ship has the back blown off. not for 10 seconds either. i have a 7.1 setup. that was the first title i ripped and the first rip also had video glitches but on subsequent rip the video was fine. recall back then it also took about 8 painful hours for a single rip

also if you dont mind my asking, what are you using for the .4 speakers? i am currently researching…


#12

I recently re-ripped GoG v2 with the latest version of DeUHD (as with all my discs for that matter), but I have not had time to watch it. I am curious where the dropouts are as well. We know with Pirates they occur in the same place every time.

As for speakers, well, I suggest sticking with something similar to what you are using in the rest of your 7.1 setup for tonal matching. I am using all MartinLogan speakers for the base channels and therefore I am using ML bookshelfs mounted at the wall/ceiling line. I used to mount them to the ceiling when I had a dedicated HT room, but I do not have one in my new house (hence the reason I sold the projector too).


#13

I have to check and see what Sonus Faber is currently offering.

My seven speakers are all Sonus Faber and the sub is a Rel (fantastic sub!)


#14

Nice. I have a set of Sonus Faber as well. They are wonderful speakers, but I don’t recall them making anything that would be very Atmos/DTS:X oriented. It’s actually the reason I sold off the surrounds and center and kept the stereo pair. I went ML for my home theater as they had a better selection of choices for that use.

I am using two Rythmik FV15HP subs.


#15

I went for AxiomAudio for my 7.2.4 and due to the location of the center had them make a “custom” in wall M80 with shallower depth. I need to get up on a ladder and check out one of the ceiling speakers as I get a rattle at some freq. I think the installers got a packer loose :unamused: I will need to re-watch GGII for find the spots but it was far way in the there was a series of them.


#16

Got his response from Hendrik/Nev… I’ve now asked him if it is worth opening a bug on the ffmpeg tracker but I’ve not heard back.

[QUOTE=nevcairiel;1828678]The actual layout of the Dolby MAT frame used to encapsulate TrueHD for HDMI transmission is unknown and undocumented, so unless someone finds the specification how to do this, I’m afraid there isn’t even a starting point to start looking.[/QUOTE]


#17

Interesting. I wonder if Android TV is using the same pass-through methodology as FFMPEG? I assumed it was the same IEC 61937 method as we have always used.


#18

GG2 Drops out at 1:09:24 where TaserFace gets killed is one example.


#19

I can confirm the dropout via playback on the Shield TV via Plex.


#20

I have no idea how to progress to getting this fixed at this stage. I guess we will see what happens when the VUK comes out and it impacts more people or more discs. At that point it may get some attention but for now this discs are unwatchable for me.