Lossless codecs (obviously, just some don't know what that means), Opus and Vorbis on higher bitrates. Holy molly, I completely missed AAC and one surprise that I genuinely think was years ahead of its time: WMA.
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Atmos finally decoded in PC/Mac
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generalguy
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By the way, for TrueHD/MLP files they tack on the object stream as I believe the 3rd or 4th stream. Might be possible to decode it or at least separate/remux/demux it
See: https://github.com/FFmpeg/FFmpeg/bl...ae7855d07b2a6da8b537/libavcodec/mlpdec.c#L388
The reason ffmpeg strips it out is because it completely ignores it, so any downstream encoder aside from "copy" is unaware of the data stream.
Figuring out a way to convert it to the "JOC" bit of e-ac3 is a bit a mystery but perhaps it could be done to allow remixes to work right on Apple TV
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It's possible to separate, but it's still an undocumented bitstream. Muxing is not really possible, it will result in noise.
They are completely different formats. E-AC-3 has absolutely minimal precision, sometimes as low as 5 bits. Just the TrueHD Atmos metadata weighs as much as the entire E-AC-3 stream.
generalguy
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Boo, ok, figured it wouldn't be that easy.
Do you know of any work on reverse-engineering the Atmos metadata in either format? I'm assuming the E-AC-3 JOC is documented in whatever ATSC/SMPTE standard it got stuffed in.
I wish @retro alters the click-bait post title. Besides, what is linked is neither practical nor there is any finality in the availability of the decoding on PC/Mac. The Dolby Media Encoder was shipped with the Dolby Reference Player since the encoder's launch, the player was available since the launch of the file based encoder.
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E-AC-3 JOC is done in Cavern, but TrueHD is completely closed source, and I think it always will be (DD+ had to be an open standard to compete in broadcast, and this made them lose all their royalties, even the encoders are now made by third parties).
Simply ignore the thread if not interested. There are two other methods you don't bother to mention in your post.
Cavern and direct decode from Apple Music on a Mac.
As you may know Atmos is an object sound system, it’s basically data. Depending on the speaker setup you have defined, from 7.1.2 to 9.1.6, the number of decoded tracks should differ. I do not see any such settings on the MacOS. Maybe you can enlighten us?
I am not familiar with Cavern and how they can get around licensing. However, as it’s only specified to work with Dolby Digital Plus, it’s decoding a lossy signal.
Apple is lossy too so I won't waste your time. The info is out there.
This is what Dolby says about Atmos on macOS: can you explain how can this can be seen as decoding to use in a home theatre system?
Mac laptops released in 2018 or later can play Dolby Atmos and Dolby Audio content over the device speakers for a great spatial and immersive audio experience.
Dolby Audio Apple macOS Overview Dolby Developer | Dolby Developer
Read the Overview on Dolby Developer to learn how to encode your macOS content in Dolby Digital Plus.developer.dolby.com
mkt
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Audio MIDI Setup?
Thank you.
One assumes information given by the creator of a format would be the correct one. I wonder why Dolby specifically said “device speakers”, which looks to be wrong.
However, the article you posted says that only Apple Music and Apple TV apps works. Does that mean, no Netflix, Disney+, HBO, or Amazon streaming, nor Blue-ray disk playback?
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Indeed!
I don't use that method. You can loopback too for archiving. I don't care about video. I use DRP. I have compared DRP/Tidal vs Loopbacked Mac/Apple decoding and they sounded identical. Blu-ray Atmos music mixes are scarce, unlike streaming. It's a tradeoff but I am very happy with it.
Where as to me Atmos is mainly about film.
From what I read Atmos can be decoded on Apple Music & TV apps. If your source can be recognised by them you can have discrete channel output from compressed Atmos signal.
generalguy
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Damn. I know truehd is basically meridian lossless with some extentions like ffmpeg can decode but I was hoping that the metadata track was similar between it and JOC.
I guess someone in a country that doesn't care about software patents has to reverse engineer it from the encoder
Not a merry wish for a company's IP to be hacked and the livelihood of almost 3000 people directly and many more indirectly effected just for one's pleasure...I guess someone in a country that doesn't care about software patents has to reverse engineer it from the encoder
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