As of this week, Apple has officially released Spatial audio with Dolby Atmos and Lossless audio options to its Apple Music service. For audiophiles this is a pretty awesome feature and even so for those less audio conscious consumers. While you cannot really tell a difference on using lossless audio with regards to Apple's Bluetooth headphones or really any bluetooth set of speakers (use airplay or a lightning to headphone adapter for that). Spatial audio does make a notable difference. But why? What is so special about it?
Spatial Atmos audio files have a distinct feature that most people may not realize. Instead of simply having 2 channels for stereo songs (left and right respectively), Atmos offers up to 128 channels of audio streams that can be used to combine and form a sound field. Not only do songs gain a depth of field that are not normally produced making instruments sound more clear and present in your mind, this separation of channels also benefits audio compression in a way. No, I am not referring to file compression or file size.
What is an audio compressor? In simple terms, a compressor is often used to reduce an audio level in a final output when it goes beyond a certain limit. It tightens the sound and reduces the gain rate by a specified ratio. Common ratios might be a 2:1 or 4:1 gain reduction as part of the compression process. A lot of songs use compressors on different parts of the audio track and also on the overall mix to help tighten up the song or make the song sound bigger within the same amount of headroom. The downside, however, is it can cause the sound of one instrument to affect the audible clarity of another instrument (when using a compressor on the overall mix).
Most non lossless compression codecs apply a basic compressor to the mix. This is done as part of an effort to normalize the sound level across the song and also can help generalize some parts of the song for better file compression ratios. The downside of this can be especially noticed in the low end as well. A kick drum's impact may trip a compression threshold causing the entire mix to reduce in gain thereby muddying the bass drum or the electric guitar a bit.
This is where there is an advantage to spatial audio tracks. Since the instruments are typically tracked in distinct tracks instead of a simple left/right channel, a final compressor isn't necessarily in existence at the point of recording. This means any type of overall compression can happen on the codec that is responsible for decoding and presenting the spatial audio to the speakers or headphones the listener is using. Not only do instruments better envelop you as you listen to the music, their audio characteristics have less risk of impacting the other instruments in the sound field. Songs can have much clearer audio and it can spread out around you in a more consuming manner.
Bass tracks also gain a huge benefit. Audio characteristics for a subwoofer can be kept in a separate channel as well. The main benefit is the sound field can be virtually reconstructed on any Atmos enabled system in a way that the speaker setup is best suited to reproduce it in. Headphones, can use virtual surround to mimic the field. Dolby Atmos receivers can use however many surround sound channels you have to also reproduce the desired sound field. Audio shifts from simply defining the mix as a left and right stereo channel and instead enables the placement of the audio mix to be represented best by the device playing it.
Spatial Atmos audio files have a distinct feature that most people may not realize. Instead of simply having 2 channels for stereo songs (left and right respectively), Atmos offers up to 128 channels of audio streams that can be used to combine and form a sound field. Not only do songs gain a depth of field that are not normally produced making instruments sound more clear and present in your mind, this separation of channels also benefits audio compression in a way. No, I am not referring to file compression or file size.
What is an audio compressor? In simple terms, a compressor is often used to reduce an audio level in a final output when it goes beyond a certain limit. It tightens the sound and reduces the gain rate by a specified ratio. Common ratios might be a 2:1 or 4:1 gain reduction as part of the compression process. A lot of songs use compressors on different parts of the audio track and also on the overall mix to help tighten up the song or make the song sound bigger within the same amount of headroom. The downside, however, is it can cause the sound of one instrument to affect the audible clarity of another instrument (when using a compressor on the overall mix).
Most non lossless compression codecs apply a basic compressor to the mix. This is done as part of an effort to normalize the sound level across the song and also can help generalize some parts of the song for better file compression ratios. The downside of this can be especially noticed in the low end as well. A kick drum's impact may trip a compression threshold causing the entire mix to reduce in gain thereby muddying the bass drum or the electric guitar a bit.
This is where there is an advantage to spatial audio tracks. Since the instruments are typically tracked in distinct tracks instead of a simple left/right channel, a final compressor isn't necessarily in existence at the point of recording. This means any type of overall compression can happen on the codec that is responsible for decoding and presenting the spatial audio to the speakers or headphones the listener is using. Not only do instruments better envelop you as you listen to the music, their audio characteristics have less risk of impacting the other instruments in the sound field. Songs can have much clearer audio and it can spread out around you in a more consuming manner.
Bass tracks also gain a huge benefit. Audio characteristics for a subwoofer can be kept in a separate channel as well. The main benefit is the sound field can be virtually reconstructed on any Atmos enabled system in a way that the speaker setup is best suited to reproduce it in. Headphones, can use virtual surround to mimic the field. Dolby Atmos receivers can use however many surround sound channels you have to also reproduce the desired sound field. Audio shifts from simply defining the mix as a left and right stereo channel and instead enables the placement of the audio mix to be represented best by the device playing it.