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Atmos encoded FLAC files?

EB1000

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Hi

As you know, Tidal offers Dolby Atmos music. The latest version of Tidal-Media-Downloader now supports downloading of Dolby Atmos encoded music as lossless FLAC files. I gave it a try and the downloaded FLAC was indeed bigger in size, 24bit/48kHz with larger bitrate than the average CD quality FLAC. It is not an MQA file, and it plays normally in stereo using any player. Here is a sample of an Atmos encoded FLAC:

https://www.dropbox.com/s/ueal4v5fq3u276a/05 - Illenium - First Time.flac?dl=0

I wonder how did they manage to add the additional channels on object metadata to the FLAC format while leaving it backward compatible with non Atmos enabled players? Is there a way to decode such FLAC file and sent the Dolby True HD Atmos bitstream to an AVR? Perhaps Jriver can?

This could be a very interesting project for a foobar2000 or kodi extension/addon.

Is there a FLAC analyzing tool for Windows that can try to analyze such file?

Thanks
 

Grooved

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Hi,

I did not check if there is Atmos content in it, but your file is a 24/48 MQA file, with an original sample rate of 96kHz (sample rate of the master, and sample rate once the file is decoded by MQA Core decoder).
 

danadam

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the downloaded FLAC was indeed bigger in size, 24bit/48kHz with larger bitrate than the average CD quality FLAC.
As 24bit/48kHz files usually are, no matter if they are MQA/Atmos or not. That's because CD quality is 16bit/44.1kHz, so it's automatically over 1/3 less data to compress.
 

danadam

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The latest version of Tidal-Media-Downloader now supports downloading of Dolby Atmos encoded music as lossless FLAC files.
BTW, where is this information from? The only thing the release notes or the updatelog say about atmos is:
Code:
v2021-05-31
  (latest version)
v2020-12-17
  Show DOLBY_ATMOS flag [A]
v2020-06-14
  Download Dolby Atmos(AC4 Codec\Low Quality\Mp4 format)
so not a FLAC but MP4.
 

AudioScience Enthusiast

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From my basic reading, my understanding is that FLAC may contain multi-channel tracks but only MKV can encode object-based info to be decoded by capable AVRs.

I am curious about this as well if there is a more technical explanation.
 

sarumbear

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From my basic reading, my understanding is that FLAC may contain multi-channel tracks but only MKV can encode object-based info to be decoded by capable AVRs.

I am curious about this as well if there is a more technical explanation.
Who does the Dolby Atmos decoding?
 

sarumbear

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Directly by AVR? Or bitstream from one of the Atmos-capable players like Shield TV?
It’s interesting to see if it works. More interesting is Dolby allowing their encoding to be integrated with another, especially an open source one. Maybe what Tidal means is stereo down mix of Atmos files?
 

AudioScience Enthusiast

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Using the link provided by @danadam, I can see the full changelog:

v2020-06-14​

  • Reduce the number of logins
  • Use another login method(from Redsea)
  • Download Dolby Atmos(AC4 Codec\Low Quality\Mp4 format)
  • Download SONY_360RA(MHA1 Codec\Low Quality\Mp4 format)
  • Skip convert to mp4 if File-Codec is AC4 or MHA1
  • Fixed the bug of Download-HIRES

It looks like Atmos is just downloaded as mp4 but wrapped in FLAC format? So maybe it does carry Atmos then?
 

sarumbear

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