Understand the technical difference between the two Atmos tracks included in your MKV (Dolby Atmos and Dolby TrueHD Atmos) and why TrueHD is the "Studio Master" standard.
The Technical Difference: While both tracks carry "Dolby Atmos" 3D metadata, they use very different "carrier" technology.
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Dolby TrueHD with Atmos (Lossless): This is a bit-for-bit replica of the studio master tape. It has a variable bitrate that can reach 18,000 kbps. It captures every nuance without throwing away any data. It is the gold standard for home cinema.
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Dolby Digital Plus with Atmos / E-AC3 (Lossy): This is the format used by streaming services like Netflix. It is compressed to roughly 768 kbps to save bandwidth. To achieve this, it discards high-frequency data (usually above 20kHz) and simplifies the complexity of the audio.
Why it matters for music: instruments are often placed in the "height" channels for immersive effects.
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Dolby TrueHD Atmos keeps these instruments focused and clear.
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Dolby Atmos (E-AC3) can sometimes introduce "artifacts" or a "swirling" digital sound in the overhead speakers because of the heavy compression.