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Definitions

Raw Stream:  

• = The audio stream

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• as coming from a source

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• (PCM format assumed, but might possibly use other encoding such as Dolby for multi-channel, in that case indicate this).  
  • There shall be none or minimal application of Gain/Volume (stream should be at nominal / maximum volume), Effects (no effects applied), or

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• • Mixing (one stream

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• • at a time).
  • We can however consider 2-ch stereo, or multi-channel, as a single stream as long as it is transferred so that it can be trivially separated for treating the channels separately in the outside system.

Raw stream metadata:  Information about  

• = Information about the stream

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• .
  • Where it is coming from (an app?  the HMI?  the system?)

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• • .  
  • What type of audio is it (Audio track of a video playback?  Music?  Navigation prompt?  Urgent and safety-critical warning message?  HMI feedback because you pressed a button?).  
• Metadata is used in an external mixing and effects system to take the decision about how to mix, how to apply volume and effects, and especially for priority of one sound over another

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• .