Dolby Atmos and REW

[SimpleDude]

Thanks, did you have any recommendations about using the 0° or the 90° file for the UMIK1 for Atmos channnel measurements?

 

[serko70]

PS: Make sure to turn any kind of loudness/bass management "off" in your receiver. It's "on" by default and this may decrease the volume of the sweeps massively.
Also, with some models there's no defeating dialnorm settings by turning loudness management off:

Defeating dialnorm

Dialnorm is a type of metadata typically included in lossy/streaming Dolby Digital (DD/AC3) and Dolby Digital + (DD+/EAC3) tracks which instructs the processor to reduce master volume by an amount equal to the difference between -31dB and the value stored in the metadata. Many of us would...

www.avsforum.com

 

[thothsong]

Thanks, did you have any recommendations about using the 0° or the 90° file for the UMIK1 for Atmos channnel measurements?

If the height speakers are at the standard 45° angle to the listening position, then I don't know which is better, sorry.

 

[SimpleDude]

No problem, I ended up using the 90 degree file as that’s what Dirac Live used, applied frequency response curve corrections and it sounds quite good and balanced. I changed the AVR MV to -18 and kept the REW sweeps at -12.

 

[serko70]

At one point I toyed with the idea of buying a 1-year license to the Dolby Media Encoder, because TrueHD Atmos sweeps would be nice to have, but it seems to only be available to companies, not individuals..

Correct me if I am wrong but will they not need to have .mlp extension which is not playable with public media players?

 

[thothsong]

Correct me if I am wrong but will they not need to have .mlp extension which is not playable with public media players?

VLC will play .mlp files, and various apps will play TrueHD Atmos in an mp4 or mkv container.

 

[serko70]

VLC will play .mlp files, and various apps will play TrueHD Atmos in an mp4 or mkv container.

What do you think of this trial of mine?

 

[thothsong]

What do you think of this trial of mine?

How did you produce it?

 

[serko70]

How did you produce it?

I'll leave you in suspense for a bit

 

[sumo]

@thothsong When playing back the TML and TMR signals, I also the corresponding front and rear height speakers also seem to be playing. I also see this reflected in the peak level view for each channel on my Trinnov processor. The other height channels work fine. Have you seen this?

Also, what level are these tracks mixed at? They play back at quite a low level compared to tones generated directly within REW. Thx!

 

[sumo]

What app are folks using to play back these files? I was only able to get JRiver to bitstream. The other players, VLC and Media Player, always decode/downmix the tracks down to PCM.

 

[thothsong]

When playing back the TML and TMR signals, I also the corresponding front and rear height speakers also seem to be playing. I also see this reflected in the peak level view for each channel on my Trinnov processor. The other height channels work fine. Have you seen this?

I only have a x.x.4 system, so I've never been able to test the TML/R signals properly. But, I've just recently figured out another unfortunate fact about how the AWS service encoded the files. There's a flag in the DD+ Atmos metadata that can be used to specify whether bed channels are intended to be "distributed to multiple appropriate loudspeakers". That flag is unfortunately set in all of the sweeps, so it's quite possible that's causing the middle sweeps to be expanded.

Also, what level are these tracks mixed at?

Unfortunately, the AWS service used to encode them doesn't allow dialnorm to be explicitly configured, the service sets it automatically, and it ends up setting dialnorm so the volume is very low.

What app are folks using to play back these files?

VLC will play them, but you need to enable HDMI/SPDIF audio passthrough in the audio settings. The Movies & TV also works. On Windows 10, Windows Media Player (not the same as Media Player) works; on Windows 11, you need to use Windows Media Player Legacy instead.

Although @serko70 hasn't announced it here, you're now better off using his lossless TrueHD Atmos 9.1.6 sweeps (download link in the YT description):

Those files can be played with VLC.

 

[canavan]

I only have a x.x.4 system, so I've never been able to test the TML/R signals properly. But, I've just recently figured out another unfortunate fact about how the AWS service encoded the files. There's a flag in the DD+ Atmos metadata that can be used to specify whether bed channels are intended to be "distributed to multiple appropriate loudspeakers". That flag is unfortunately set in all of the sweeps, so it's quite possible that's causing the middle sweeps to be expanded.


Unfortunately, the AWS service used to encode them doesn't allow dialnorm to be explicitly configured, the service sets it automatically, and it ends up setting dialnorm so the volume is very low.


VLC will play them, but you need to enable HDMI/SPDIF audio passthrough in the audio settings. The Movies & TV also works. On Windows 10, Windows Media Player (not the same as Media Player) works; on Windows 11, you need to use Windows Media Player Legacy instead.

Although @serko70 hasn't announced it here, you're now better off using his lossless TrueHD Atmos 9.1.6 sweeps (download link in the YT description):

Those files can be played with VLC.

They also play on some Blu Ray players, such as those made by Oppo, or basically anything that runs Kodi.

@serko70's files playing back with a 9.1.6 layout (starting with the right wide, if I remember correctly):

thotsong's AWS-encoded files, showing use of multiple speakers:

I've also tried the same preset / layout as with serko70's files, with the same effect. I wouldn't be surprised if one can assemble a speaker layout that uses only one speaker for each sweep, but my attempts so far weren't successful.

 

[thothsong]

I've also tried the same preset / layout as with serko70's files, with the same effect. I wouldn't be surprised if one can assemble a speaker layout that uses only one speaker for each sweep, but my attempts so far weren't successful.

Hmm, I don't know if @serko70 tested on an x.x.6 system.

 

[sumo]

I only have a x.x.4 system, so I've never been able to test the TML/R signals properly. But, I've just recently figured out another unfortunate fact about how the AWS service encoded the files. There's a flag in the DD+ Atmos metadata that can be used to specify whether bed channels are intended to be "distributed to multiple appropriate loudspeakers". That flag is unfortunately set in all of the sweeps, so it's quite possible that's causing the middle sweeps to be expanded.


Unfortunately, the AWS service used to encode them doesn't allow dialnorm to be explicitly configured, the service sets it automatically, and it ends up setting dialnorm so the volume is very low.


VLC will play them, but you need to enable HDMI/SPDIF audio passthrough in the audio settings. The Movies & TV also works. On Windows 10, Windows Media Player (not the same as Media Player) works; on Windows 11, you need to use Windows Media Player Legacy instead.

Although @serko70 hasn't announced it here, you're now better off using his lossless TrueHD Atmos 9.1.6 sweeps (download link in the YT description):

Those files can be played with VLC.

I somehow missed OCA's Youtube post. Thx for the link. I downloaded those files and the chapter grouping makes it quite easy to hop around different speakers. The sweeps on his files seem to be good except for the front wides; for those speakers the side surrounds are also enabled.

Regarding VLC ... my issue with the program had to do with running on a machine where Windows was running within Parallels on a Mac. On that machine, it just could not get bitstream output. I gave up trying to figure that out and instead moved to another machine running Windows natively. The measurement setup is just a bit complicated as the native Win machine is in another room, but connected to my system. The microphone is connected to a laptop in the media room which runs REW.

Thx for your help.

 

[serko70]

All other channels are muted while producing the sweep for a particular channel but I don't have top middle and front wide channels to test (interestingly only the channels I don't have are problematic). These 256k long TrueHD sweeps were created more recently and in the very low probability case that I have done channel muting mistakes, it's extremely unlikely that I have repeated the exact same mistakes in these ones:

Optimal Atmos Sweeps 256k - Google Drive

drive.google.com

Let me know if FW and TM channels still have the problems you have mentioned.

 

[Medi0gre]

@thothsong @serko70 Thank you for your efforts!
This has been a amazing transformation of my room. I've been doing it wrong.. for a long time, and these files and methods have been amazing in fixing my rooms issues i didn't even know i had

 

[natty]

Before I go too far down the rabbit hole, here are four files that others can test, to see if I'm on a useful track. These are audio-only mp4 measurement sweep files for height speakers (x.x.4), with timing ref in the Center channel. They are derived from an REW-generated sweep file with parameters 1M length, 20 Hz to 20 kHz, -12 dBFS, 48 kHz, 32-bit Float, so you should use those parameters to generate your local sweep file to load into REW (resulting file name is 1MMeasSweep_20_to_20000_-12_dBFS_48k_Float_L_refR.wav).

https://rew-atmos-files.s3.amazonaws.com/1M_20_to_20000_48k_Ltf.mp4

https://rew-atmos-files.s3.amazonaws.com/1M_20_to_20000_48k_Rtf.mp4

https://rew-atmos-files.s3.amazonaws.com/1M_20_to_20000_48k_Ltr.mp4

https://rew-atmos-files.s3.amazonaws.com/1M_20_to_20000_48k_Rtr.mp4

Let me know if they work for you, or if you don't like the parameters. The overall volume level is lower than what I expected, so that's something still to investigate.

Edit: these links no longer work, see later post for full download.

Great stuff. Thanks for doing this and sharing the files!

I'm not quite sure how to use them in REW yes, but I was able to play them back through my AppleTV using Infuse and use them for simple level checking of each channel (which one cannot really do with my AVR test tones since the test tone bypass room EQ, which can have an impact on levels).

 

[Navish360]

@serko70 @thothsong Do you have any way to make pink noise at-30 dBFS for the atmos channels? I'm currently running a 7.1.4, and level matching at 70db @ 0 MV with the -30dbfs pink noise via REW.

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[natty]

@serko70 @thothsong Do you have any way to make pink noise at-30 dBFS for the atmos channels? I'm currently running a 7.1.4, and level matching at 70db @ 0 MV with the -30dbfs pink noise via REW.

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That’s a great idea.

 

[serko70]

That’s a great idea.

I had created lossless M-Noise sweeps a while back (mkv format, 46 seconds each). They are all at equal volume to each other with dialnorm settings off but there's no easy way to measure their dbFS levels accurately. Still, it will help with level matching probably even better than pink noise as they have higher crest factor:

 

[thothsong]

Dolby provides DD+ Atmos full range pink noise files:

https://download.dolby.com/us/en/test-tones/dolby-test-tones_5_1_2.mp4

https://download.dolby.com/us/en/test-tones/dolby-test-tones_7_1_4.mp4

https://download.dolby.com/us/en/test-tones/dolby-test-tones_9_1_6.mp4

I have in the past produced DD+ Atmos 7.1.4 SpeakerCal/SubCal pink noise files:
The files are named for a Samsung soundbar, but the mapping should be clear.

 

[natty]

Dolby provides DD+ Atmos full range pink noise files:

https://download.dolby.com/us/en/test-tones/dolby-test-tones_5_1_2.mp4

https://download.dolby.com/us/en/test-tones/dolby-test-tones_7_1_4.mp4

https://download.dolby.com/us/en/test-tones/dolby-test-tones_9_1_6.mp4

I have in the past produced DD+ Atmos 7.1.4 SpeakerCal/SubCal pink noise files:
The files are named for a Samsung soundbar, but the mapping should be clear.

Fantastic! Thanks for sharing!

 

[Navish360]

@thothsong Any idea what dBFS these are recorded in?

 

[thothsong]

@thothsong Any idea what dBFS these are recorded in?

I don't know for the Dolby files. For my files, the source files were generated with REW using -12 dBFS, but there's no way to control the Dolby dialnorm for the AWS output, and the dialnorm used is 16.