ah OK. @ChuckPa can you elaborate a little more on this hypothesis?
Pg. 11 of the Dolby Atmos for Home Theater white paper may shed some light for you.
Thanks for that so is Dolby MAT
always in the Dolby Atmos True-HD Codec transition protocol layer. Or would there ever be an instance where Dolby MAT isn’t involved in the audio codecs transition from start to finish so to speak? I guess what I’m asking is Dolby MAT always involved with all atmos tracks/codecs?
Dolby MAT 1.0 is used to encapsulate Dolby TrueHD
Dolby MAT 2.0 is used to encapsulate Dolby TrueHD and Atmos spatial metadata
Interesting Thanks. Yeah you all are far beyond my knowledge in this space. I apologize to all involved in my earlier rants. I’m just glad it’s being observed. Goodluck with getting Google on board. Thanks for your time in educating us here.
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More insight on TrueHD and MAT courtesy of Wikipedia excerpt:
Transport
Audio encoded using Dolby TrueHD may be transported to A/V receivers in one of three ways depending on player and/or receiver support:[3][4]
- Over 6 or 8 RCA connectors as analog audio, using the player’s internal decoder and digital-to-analog converter (DAC).
- Over HDMI 1.1 (or higher) connections as 6 or 8-channel Linear PCM, using the player’s decoder and the AV receiver’s DAC.
- Over HDMI 1.3 (or higher) connections as the original Dolby TrueHD bitstream encapsulated in MAT[5](Metadata-Enhanced Audio Transport) frames, with decoding and DAC both done by the AV receiver.
The Shield will passthrough pre-Atmos Dolby TrueHD encapsulated with Dolby MAT 1.0 without problems. With the advent of Dolby Atmos TrueHD premiering with 4K BDs and eventually included on BDs, the time specific HD audio dropouts reared its ugly head. As time progresses and more people consume media with the Dolby Atmos TrueHD, the reports of this issue are becoming more widespread. It has been made more confusing and complex to troubleshoot with the random HD audio passthrough dropout bugs cropping up.
Thanks Achilles for jumping in. I was preoccupied with holiday festivities.
Yes, I was referring to the transport from the app through to the underlying audio layers of the Shield OS which sends the audio packets to the receiver
I suspect there is a presumption of MAT 1.0.
I tested this by watching TrueHD 7.1 1080p H.264. There were no drops but I didn’t expect any because, if my hypthesis is correct, the deployed code is not expecting MAT 2.0 (as Achilles and I discussed ) but is more than capable of handling the packets ( Audio frames to use precise terminology ) coming from the player app for MAT 1.0
Is there any links to the upstream tracking of issue on Google’s end? I saw the one issue about increasing buffer size on github, not aware of any other open (kinda wondering if maybe it fell inbetween the cracks).
MediaInfo 19.09 can gather some of the bitrate information on certain discs. Output of two scenarios below. The audio bitrate is significantly higher, notably the peak of Big Hero 6.
(Shield Pro/Audio passthrough to AVR w/ Atmos setup/Various Apps - Plex/Kodi etc)
SpiderVerse 4k Remux - plays back fine:
Audio #1
ID : 2
ID in the original source medium : 4352 (0x1100)
Format : MLP FBA 16-ch
Format/Info : Meridian Lossless Packing FBA with 16-channel presentation
Commercial name : Dolby TrueHD with Dolby Atmos
Codec ID : A_TRUEHD
Duration : 1 h 56 min
Bit rate mode : Variable
Bit rate : 3 267 kb/s
Maximum bit rate : 4 935 kb/s
Channel(s) : 8 channels
Channel layout : L R C LFE Ls Rs Lb Rb
Sampling rate : 48.0 kHz
Frame rate : 1 200.000 FPS (40 SPF)
Bit depth : 24 bits
Compression mode : Lossless
Stream size : 2.67 GiB (6%)
Title : Surround 7.1
Language : English
Default : Yes
Forced : No
Original source medium : Blu-ray
Number of dynamic objects : 11
Bed channel count : 1 channel
Bed channel configuration : LFE
Big Hero 6 4k Remix - drops audio in certain high action scenes:
Audio #1
ID : 2
ID in the original source medium : 4352 (0x1100)
Format : MLP FBA 16-ch
Format/Info : Meridian Lossless Packing FBA with 16-channel presentation
Commercial name : Dolby TrueHD with Dolby Atmos
Codec ID : A_TRUEHD
Duration : 1 h 41 min
Bit rate mode : Variable
Bit rate : 7 470 kb/s
Maximum bit rate : 11.2 Mb/s
Channel(s) : 8 channels
Channel layout : L R C LFE Ls Rs Lb Rb
Sampling rate : 48.0 kHz
Frame rate : 1 200.000 FPS (40 SPF)
Bit depth : 24 bits
Compression mode : Lossless
Stream size : 5.32 GiB (11%)
Title : Surround 7.1
Language : English
Default : Yes
Forced : No
Original source medium : Blu-ray
Number of dynamic objects : 13
Bed channel count : 1 channel
Bed channel configuration : LFE
Is this the right place to track the latest or is there a GitHub issue or something else? I noticed this today with the Beatles Abbey Road Atmos track. The other HD tracks work fine.
FYI, new Shield update just released. Includes fix audio drop outs. Follow link for additional info.
SHIELD Experience Update 8.0.2 now available
Update (1/27/20): Today we just released software upgrade 8.0.2 (32.5.205.105) for all 2015 and 2017 SHIELD and SHIELD Pro units.
- Resolves audio drop issues when playing high bit-rate or DolbyTrueHD streams over HDMI passthrough.
Updated and still get the same drop outs on TrueHD titles such as Toy story 4, tangled etc. Man was so happy when I saw that fix in the logs…
Rats. 
Hoping it would fix things. Downloading now. Will test later today.
FYI:
@Achilles did perform these tests, btw.
Nothing has changed here. Random HD audio dropouts is what was resolved by Nvidia. The time specific HD audio droputs are due to insufficient frame size for Dolby MAT 2.0 encapsulation that is used for Dolby Atmos TrueHD. This has to be fixed by Google+Nvidia. This impacts Emby, Kodi and Plex on the Nvidia Shield. Users need to make more posting on Nvidia’s forums if we are to get traction on a resolution for this issue.
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Already posted on the Shield forum, Also doesn’t help when you get a reply from a user saying “Others have reported those files damaged. I don’t believe it’s the Shield in this case.” so frustrating users Spreading misinformation.
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FWIW, so far this update fixed all the drop outs I was getting on dts hd ma (Bourne series).
Haven’t got to truehd/atmos yet.
I tried the Beatles Abbey Road Atmos and it’s the same as before with audio drop outs.
Oooo I didn’t know there was another atmos album released, I have the R.E.M. Automatic for the People atmos release.
It’s pretty good but not my favorite R.E.M. album.
How is abbey road?
