User16840867725783411178 (Mind The Gap) asked a question.
Does a 5.1 Downmix MP4 file require a Dolby Atmos receiver/soundbar to playback?
Or can a conventional 5.1 receiver play it back.
- AdamP (Dolby Labs)Hi,
The codec used in the the MP4 exported from the Renderer is DDPlusJOC. All of the audio from the Atmos master is contained in the 5.1 core or DDPlusJOC. A 5.1 device that is capable of decoding DD+ (any semi-recent AVR) will decode the 5.1 audio and ignore the additional metadata required to reconstruct the Atmos presentation. Many AVRs can play an MP4 file on a connected USB drive but some may require the audio to be connected over HDMI via a Blu-ray player or DMA.
What is the use case for wanted to decode only the 5.1 core?
Thanks,
AdamExpand Post - User16840867725783411178 (Mind The Gap)Hi Adam
Thanks for your reply. I need to reference my Dolby Atmos mixes on a speaker system. Currently, I'm using headphones which isn't ideal. Since my home theater is a 5.1 setup, I thought about down mixing them to 5.1 so they can be played on my home theater. Not ideal, I know. But at least I can get an idea of the Dolby Atmos mix on a sound system.
Since my receiver, Yamaha V385, decodes Dolby audio but is not a Dolby Atmos device, what metadata would it be missing in a 5.1 downmix? Would it just be missing panning data or panning plus beds and objects? If the latter, then clearly that wouldn't be helpful.
Also, to set up an adequate consumer Dolby Atmos speaker system, could I just use a soundbar like the Bose Soundbar 900? Obviously, it's not a true immersive speaker system but at least it can play a Dolby Atmos mix.
Finally, please feel free to suggest an economical alternative so I can simply reference my headphone mixes on a speaker system.
Many thanks,
MarcExpand Post - AdamP (Dolby Labs)Hey Marc,
If you use the MP4 export from the Renderer, the Atmos master goes through spatial coding and is rendered (with the default settings) to 7.1 and downmixed to 5.1. All the bed and object audio is there. It is definitely a good idea to be able to your Atmos mix downmixed to 5.1 through speakers.
I'd suggest taking a look at our online training at learning.dolby.com and having a look at the "Music" course. Spatial coding is covered in the Atmos basics section and a shallow dive into the DDPlusJOC codec is there (in Appendix C) as well. The same user/pw used on this site works there. That will be quicker and more efficient than me diving into it her.
Re: Bose soundbar. QC'ing on a consumer Atmos enabled soundbar is likewise totally valuable. If you have the option with the satellite surrounds and sub that would be much better.
Are either a 5.1 speaker AVR or an Atmos enabled soundbar a substitute for mixing on a discrete 7.1.4 speaker system....No. But that shouldn't discourage you from using the above for QC Getting into real speaker system simply isn't that cheap and we generally avoid specific recommendations. But, there are lower cost bundled options from the like of Kali Audio, IK Multimedia iloud, KRK etc. These might not get into the recommended professional studio level of adequate headroom for label reviews at a ref level of 85dB but maybe perfectly adequate for a smaller private setup. Calibration and room tuning being a separate topics.
So, no magic bullet there but working on headphones and QC on 5.1 speaker layouts, a Atmos enabled soundbar, side loading the MP4 onto Apple devices with the right headphones/buds are all good ways to assess how your Atmos mix translates to different playback scenarios.
Best,
AdamExpand Post- User16840867725783411178 (Mind The Gap)Hi Adam
Thanks again for your helpful reply. I just want to clarify a specific scenario. If I export an Atmos mix from Dolby Renderer to ADM BWF and play it back via Blu Ray on a Yamaha V385 receiver (which supports Dolby audio but not Atmos) with a 5.1 speaker configuration, will it only playback the beds and objects placed in the 5.1 config of a 7.1.4 mix?
When I played this export back, it definitely sounded like elements were missing. But when I did a downmix to 5.1 in Dolby Renderer and played it back on the same system, I could hear mostly all of the elements, though the mix was more dense.
Please let me know if my understanding is correct.
Many thanks,
MarcExpand Post
- AdamP (Dolby Labs)Hi Marc,
You can't playback the ADM BWF itself on consumer gear. Or if you can you... there is no telling what you are hearing.
If you export an MP4 from the Renderer all the Bed and Object audio is included in the 5.1 encoded as DDPlusJOC. You can experiment with the downmix and trim settings which will affect how the overhead and rear content is rendered and mixed into the 5.1.
I'm not sure what you mean by 7.1.4 mix. If your mix is using bed and dynamic objects than 7.1.4 is just a speaker layout. Are you using a bed and four static objects pinned to the overhead corners to create a 7.1.4 mix only?
The Yamaha should playback the 5.1 as it can decode the core DDPlus and ignore the Atmos related metadata. The Yamaha looks to have a USB input so you could try to playback the MP4 directly from a thumbdrive. If not and you are using a Blu-ray player, make sure it is set to bitstream passthrough so the decoding takes place on the receiver.
Best,
AdamExpand Post
If you use the MP4 export from the Renderer, the Atmos master goes through spatial coding and is rendered (with the default settings) to 7.1 and downmixed to 5.1. All the bed and object audio is there. It is definitely a good idea to be able to your Atmos mix downmixed to 5.1 through speakers.
I'd suggest taking a look at our online training at learning.dolby.com and having a look at the "Music" course. Spatial coding is covered in the Atmos basics section and a shallow dive into the DDPlusJOC codec is there (in Appendix C) as well. The same user/pw used on this site works there. That will be quicker and more efficient than me diving into it her.
Re: Bose soundbar. QC'ing on a consumer Atmos enabled soundbar is likewise totally valuable. If you have the option with the satellite surrounds and sub that would be much better.
Are either a 5.1 speaker AVR or an Atmos enabled soundbar a substitute for mixing on a discrete 7.1.4 speaker system....No. But that shouldn't discourage you from using the above for QC Getting into real speaker system simply isn't that cheap and we generally avoid specific recommendations. But, there are lower cost bundled options from the like of Kali Audio, IK Multimedia iloud, KRK etc. These might not get into the recommended professional studio level of adequate headroom for label reviews at a ref level of 85dB but maybe perfectly adequate for a smaller private setup. Calibration and room tuning being a separate topics.
So, no magic bullet there but working on headphones and QC on 5.1 speaker layouts, a Atmos enabled soundbar, side loading the MP4 onto Apple devices with the right headphones/buds are all good ways to assess how your Atmos mix translates to different playback scenarios.
Best,
Adam