A technical breakdown of spatial audio formats including Dolby Atmos, Sony 360 Reality Audio, Apple Spatial Audio, and Ambisonics. Learn how they work, which devices support them, and how to convert between formats.
Spatial audio is a family of technologies that place sound in three-dimensional space around the listener. Unlike stereo, which distributes audio across a left-right axis, and traditional surround sound, which adds rear and center channels on a horizontal plane, spatial audio introduces height channels and head-tracked positioning. The result is sound that appears to come from specific locations above, below, and around you, reacting to your head movements in real time.
The concept is not new. Binaural recording has existed since the 1880s, and cinema surround formats like Dolby Surround date back to the 1970s. What has changed is accessibility. Modern smartphones, earbuds, and streaming platforms now support spatial audio natively, bringing immersive sound to everyday listening.
This guide covers the major spatial audio formats, how they differ technically, which devices and services support them, and how to work with spatial audio files in practice.
Before diving into specific formats, it helps to understand the fundamental categories of audio spatialization.
| Feature | Stereo | Surround (5.1/7.1) | Spatial Audio |
|---|---|---|---|
| Channels | 2 (L, R) | 6 or 8 (L, R, C, LFE, LS, RS, +) | Object-based or scene-based |
| Height information | None | None | Yes (overhead channels or objects) |
| Head tracking | No | No | Yes (with compatible devices) |
| Speaker layout dependent | Yes | Yes (fixed positions) | No (renderer adapts to playback system) |
| File size vs stereo | Baseline | 3-4x larger | 1.5-3x larger (codec dependent) |
| Typical use case | Music, podcasts | Home theater, cinema | Music, film, gaming, VR/AR |
The critical distinction is between channel-based and object-based audio. Traditional surround assigns audio to fixed speaker positions. Spatial audio formats like Dolby Atmos use audio objects: sound elements with metadata describing their position in 3D space. A renderer then adapts these objects to whatever playback system is available, from a 7.1.4 speaker array to a pair of AirPods.
Key Insight: Spatial audio is not just "more channels." The object-based approach means a single mix can play optimally on headphones, soundbars, home theater systems, and car audio, with the renderer doing the translation work.
Dolby Atmos is the most widely adopted spatial audio format. Introduced in 2012 for cinema, it expanded to home theater in 2014 and to headphones and mobile in 2017. Atmos combines a 7.1.2 channel bed (7 ear-level speakers, 1 subwoofer, 2 height speakers) with up to 128 audio objects, each carrying positional metadata.
| Specification | Value |
|---|---|
| Maximum audio objects | 128 (cinema), 16 (consumer) |
| Channel bed | Up to 7.1.2 |
| Supported codecs | Dolby Digital Plus (E-AC-3), Dolby TrueHD, AC-4 |
| Container formats | MP4, MKV, ISOBMFF |
| Maximum sample rate | 48 kHz (DD+), 96 kHz (TrueHD) |
| Bit depth | Up to 24-bit |
| Head tracking | Yes (Apple devices, select headphones) |
In the production workflow, engineers use Dolby's renderer plugin inside a DAW (Logic Pro, Pro Tools, Nuendo) to position audio objects in a virtual 3D space. The mix is exported as an ADM BWF (Audio Definition Model Broadcast Wave Format) master file, which contains the full bed + objects with spatial metadata.
For distribution, this master is encoded into either:
# Check if a file contains Dolby Atmos metadata using FFprobe
ffprobe -v quiet -print_format json -show_streams -show_format input.mp4 \
| grep -i "atmos\|ec-3\|eac3\|truehd"
| Platform | Atmos Support | Codec Used |
|---|---|---|
| Apple Music | Yes | E-AC-3 JOC (AAC spatial fallback) |
| Amazon Music HD | Yes | E-AC-3 JOC |
| Tidal | Yes | E-AC-3 JOC |
| Netflix | Yes | E-AC-3 JOC / DD+ |
| Disney+ | Yes | E-AC-3 JOC |
| Blu-ray | Yes | TrueHD |
| YouTube | Limited (select content) | E-AC-3 |
| Spotify | Not yet | N/A |
Sony 360 Reality Audio (360RA) takes a different approach from Atmos. Rather than channel beds plus objects, 360RA maps every audio element as an object on a sphere around the listener. It uses MPEG-H 3D Audio as its underlying codec, which was standardized as part of MPEG-H Part 3.
| Specification | Value |
|---|---|
| Maximum audio objects | 24 (practical), 128 (spec) |
| Channel bed | None (pure object-based) |
| Codec | MPEG-H 3D Audio |
| Container format | MP4 |
| Sample rate | 48 kHz |
| Bit depth | Up to 24-bit |
| Bitrate (streaming) | 1.5-2 Mbps |
| Head tracking | Limited (Sony headphones only) |
The key philosophical difference is that 360RA is purely object-based. There is no channel bed fallback. Every element in the mix, whether it is a vocal, a guitar, or ambient reverb, is placed as an individual object on a sphere. This makes it theoretically more flexible for headphone rendering but less backward-compatible with traditional speaker systems.
Sony's tooling (360 Reality Audio Creative Suite, a plugin for DAWs) lets producers position objects on a visual sphere. The resulting file is an MPEG-H encoded MP4.
# Identify MPEG-H streams in a file
ffprobe -v quiet -print_format json -show_streams input.mp4 \
| grep -i "mpegh\|mha1\|mhm1"
| Platform | 360RA Support |
|---|---|
| Amazon Music HD | Yes |
| Tidal | Yes |
| Deezer | Yes |
| nugs.net | Yes |
| Apple Music | No |
| Spotify | No |
| Netflix | No |
360RA's main limitation is its smaller ecosystem. It requires Sony-certified hardware for the full experience (head tracking requires Sony headphones with specific chipsets), and fewer streaming services and content creators have adopted it compared to Atmos.
Apple Spatial Audio is not a single codec but a rendering technology that Apple applies on the playback side. When Apple Music says a track supports "Spatial Audio with Dolby Atmos," the source format is Dolby Atmos (E-AC-3 JOC). Apple's contribution is the head-tracked binaural renderer that runs on AirPods, Beats headphones, and Apple devices.
| Specification | Value |
|---|---|
| Source format | Dolby Atmos (E-AC-3 JOC) |
| Renderer | Apple proprietary binaural engine |
| Head tracking | Yes (AirPods Pro/Max, Beats Fit Pro, Apple Vision Pro) |
| Personalized HRTF | Yes (scanned via iPhone TrueDepth camera) |
| Supported devices | AirPods Pro/Max, Beats Fit Pro/Studio Pro, Apple TV 4K, Apple Vision Pro, Mac, iPad, iPhone |
| Fallback | Stereo AAC |
Apple's differentiator is Personalized Spatial Audio. Using the TrueDepth camera on iPhone, Apple scans the shape of your ears to generate a personalized Head-Related Transfer Function (HRTF). This HRTF is then used by the renderer to tailor the binaural output to your specific ear geometry, improving localization accuracy.
Without personalization, spatial audio renderers use a generic HRTF that works reasonably well for average ear shapes but may cause front-back confusion or poor elevation perception for some listeners. Apple's personalization measurably improves these issues.
Pro Tip: To enable Personalized Spatial Audio on iOS, go to Settings > [Your AirPods] > Personalized Spatial Audio > Personalize Spatial Audio. The scan takes about 30 seconds per ear.
Apple also applies spatial audio rendering to non-Atmos content through its "Spatialize Stereo" feature. This takes standard stereo or 5.1 audio tracks from any video or music source and renders them through a virtualized spatial field with head tracking. The result is not true spatial audio (no height information exists in the source), but it does create a convincing sense of sound being anchored in space relative to the device.
Ambisonics is the oldest spatial audio format, dating back to the 1970s. Unlike the commercial formats above, Ambisonics is an open standard that encodes a full spherical sound field using spherical harmonics. It is the native audio format for 360-degree video and VR content.
| Specification | Value |
|---|---|
| Orders | 1st (4 channels), 2nd (9), 3rd (16), 4th (25) |
| Channel format | ACN (Ambisonic Channel Number) |
| Normalization | SN3D or N3D |
| Container formats | WAV, FLAC, Opus (in WebM/MKV) |
| Sample rate | Any (commonly 48 kHz) |
| YouTube support | First-order Ambisonics (4 channels) |
| Facebook/Meta support | First and second order |
Instead of encoding discrete channels or objects, Ambisonics encodes the entire sound field at a point in space. First-Order Ambisonics (FOA) uses 4 channels (W, X, Y, Z) representing the omnidirectional pressure and three directional gradients. Higher orders add more channels for greater spatial resolution.
The critical advantage of Ambisonics is that it is speaker-layout independent at the encoding stage. A first-order Ambisonic recording can be decoded to stereo, 5.1 surround, binaural headphones, or a 22.2 speaker array. The decoder handles the translation.
# Convert a first-order Ambisonic WAV to binaural stereo
ffmpeg -i ambisonic_foa.wav \
-af "pan=stereo|FL=0.5*c0+0.5*c1+0.25*c3|FR=0.5*c0-0.5*c1+0.25*c3" \
binaural_output.wav
For proper binaural rendering with HRTF convolution, dedicated tools like the IEM Plugin Suite or Facebook's Spatial Workstation provide better results than FFmpeg's channel math.
YouTube and Meta both support Ambisonics as the audio format for 360-degree video. YouTube requires first-order Ambisonics (4 channels) in the ACN/SN3D format, muxed into the video file alongside the equirectangular video stream.
# Mux first-order Ambisonic audio with 360 video for YouTube
ffmpeg -i 360_video.mp4 -i ambisonic_audio.wav \
-c:v copy -c:a aac -b:a 256k \
-metadata:s:a:0 spatial-audio=true \
output_360.mp4
| Feature | Dolby Atmos | Sony 360RA | Apple Spatial Audio | Ambisonics |
|---|---|---|---|---|
| Type | Hybrid (bed + objects) | Pure object-based | Renderer (uses Atmos source) | Scene-based (spherical harmonics) |
| Max objects | 128 / 16 (consumer) | 24 (practical) | N/A (renderer) | N/A (continuous field) |
| Open standard | No (proprietary) | MPEG-H (standard codec) | No (proprietary renderer) | Yes (open) |
| Head tracking | Yes | Limited (Sony HW) | Yes (Apple HW) | Depends on player |
| Personalized HRTF | No | No | Yes | No (depends on decoder) |
| Backward compatible | Yes (stereo/5.1 fallback) | No | Yes (stereo AAC) | Yes (decoder dependent) |
| Best for | Music, film, streaming | Music (Sony ecosystem) | Apple device users | VR, 360 video, recording |
| Production tools | Pro Tools, Logic, Nuendo | 360RA Creative Suite | Logic Pro (via Atmos) | Reaper, IEM Suite |
| Licensing cost | Yes (Dolby license) | Yes (Sony license) | Free (Apple ecosystem) | Free (open standard) |
| Format | Typical Streaming Bitrate | Lossless Option | Latency (head tracking) |
|---|---|---|---|
| Dolby Atmos (E-AC-3 JOC) | 768 kbps | Yes (TrueHD on Blu-ray) | ~20 ms (Apple), varies |
| Sony 360RA (MPEG-H) | 1.5-2 Mbps | No (streaming only) | ~30 ms (Sony HW) |
| Apple Spatial Audio | N/A (uses Atmos source) | N/A | ~20 ms |
| Ambisonics (1st order, Opus) | 512-1024 kbps | Yes (WAV/FLAC) | Decoder dependent |
FFprobe (part of the FFmpeg suite) can reveal spatial audio metadata in most container formats.
# Full stream analysis
ffprobe -v quiet -print_format json -show_streams -show_format \
-show_entries stream=codec_name,codec_long_name,channel_layout,channels \
input_file.mp4
# Look for Atmos indicators
ffprobe -v error -show_entries stream_tags=encoder input.mp4
# Check for Ambisonic channel count (4 = FOA, 9 = SOA, 16 = TOA)
ffprobe -v error -select_streams a:0 \
-show_entries stream=channels,channel_layout input.wav
| Indicator | Likely Format |
|---|---|
Codec: eac3 with JOC metadata | Dolby Atmos |
Codec: truehd with Atmos substream | Dolby Atmos (lossless) |
Codec: mha1 or mhm1 | MPEG-H (possibly 360RA) |
| 4 audio channels, ACN/SN3D tags | First-Order Ambisonics |
| 9 or 16 audio channels | Higher-Order Ambisonics |
spatial-audio=true metadata tag | YouTube 360 Ambisonics |
MediaInfo provides a more readable output for spatial audio analysis:
mediainfo --Full input.mp4 | grep -i "atmos\|spatial\|object\|immersive\|ambi"
Converting between spatial audio formats is not straightforward. Each format encodes spatial information differently, and converting from one to another involves rendering and re-encoding, which can degrade spatial accuracy. There is no lossless round-trip between Atmos, 360RA, and Ambisonics.
Spatial to stereo downmix:
# Downmix any multi-channel file to stereo
ffmpeg -i spatial_input.mp4 -ac 2 -c:a aac -b:a 256k stereo_output.mp4
Ambisonic to binaural stereo (basic):
# First-order Ambisonics to stereo (simplified, no HRTF)
ffmpeg -i foa_input.wav -af "pan=stereo|FL<c0+0.707*c1+0.707*c3|FR<c0-0.707*c1+0.707*c3" \
-c:a pcm_s24le binaural.wav
Extract spatial audio from video:
# Extract audio stream without re-encoding (preserves spatial metadata)
ffmpeg -i input_atmos.mp4 -vn -c:a copy output_audio.mp4
For format conversions that preserve audio quality, the Audio Converter handles standard multi-channel audio, while the Video Converter can extract and re-encode audio tracks from video files containing spatial audio.
Warning: Converting Dolby Atmos or 360RA to standard stereo loses all spatial information permanently. Always keep the original spatial master file. If you need a stereo version for compatibility, create it as a separate deliverable.
First-order Ambisonics can be captured with tetrahedral microphone arrays like the Sennheiser AMBEO VR Mic, Zoom H3-VR, or Zylia ZM-1. The raw capture (A-format) is converted to B-format (ACN/SN3D) in post-production.
# Convert A-format tetrahedral recording to B-format Ambisonics
# (This requires a calibration matrix specific to your microphone)
ffmpeg -i a_format_recording.wav \
-af "pan=4c|c0=0.5*c0+0.5*c1+0.5*c2+0.5*c3|c1=0.5*c0+0.5*c1-0.5*c2-0.5*c3|c2=0.5*c0-0.5*c1+0.5*c2-0.5*c3|c3=-0.5*c0+0.5*c1+0.5*c2-0.5*c3" \
b_format_output.wav
The spatial audio landscape has consolidated around Dolby Atmos for music and film. Sony 360RA remains a niche format within Sony's ecosystem. Ambisonics holds strong in VR and 360 video.
| Service | Format | Catalog Size (approx.) | Tier Required |
|---|---|---|---|
| Apple Music | Dolby Atmos | 15,000+ tracks | All subscribers |
| Amazon Music | Dolby Atmos + 360RA | 10,000+ tracks | Unlimited tier |
| Tidal | Dolby Atmos + 360RA | 12,000+ tracks | HiFi Plus |
| Deezer | 360RA | 5,000+ tracks | Premium |
| YouTube Music | Limited Atmos | 500+ tracks | Premium |
| Spotify | Not yet available | N/A | N/A |
| Netflix | Dolby Atmos | Most originals | Premium tier |
| Disney+ | Dolby Atmos | Select titles | Standard+ tier |
Spatial audio increases file sizes compared to stereo, but modern codecs keep the overhead manageable.
| Format | Stereo Equivalent | Spatial Audio | Overhead |
|---|---|---|---|
| AAC stereo (256 kbps) | 1.9 MB/min | N/A | N/A |
| Dolby Atmos (E-AC-3 JOC, 768 kbps) | N/A | 5.7 MB/min | ~3x stereo |
| 360RA (MPEG-H, 1.5 Mbps) | N/A | 11.2 MB/min | ~6x stereo |
| FOA Ambisonics (Opus, 512 kbps) | N/A | 3.8 MB/min | ~2x stereo |
| FOA Ambisonics (FLAC lossless) | N/A | ~45 MB/min | ~24x stereo |
For managing audio file sizes, the Audio Converter supports converting between codecs with configurable bitrate and sample rate settings.
No. Any stereo headphones can play spatial audio through binaural rendering. However, head tracking (where sound stays fixed in space as you turn your head) requires compatible hardware: AirPods Pro/Max for Apple Spatial Audio, or Sony WH-1000XM5/WF-1000XM5 for 360RA. Sound quality through spatial rendering is similar across headphones, but head tracking significantly improves the immersive effect.
Upmixing stereo to spatial audio is possible using tools like Dolby Atmos Music Panner or the Spatial Audio Designer plugin. These tools use algorithms to extract and reposition elements from a stereo mix into a 3D field. The results can be impressive for some material (especially recordings with wide stereo imaging) but will never match a natively mixed spatial production.
Dolby Atmos, by a wide margin. It has the largest ecosystem, the most streaming platform support, and the best production tooling. If you are already working in Logic Pro, Atmos support is built in. For Pro Tools users, the Dolby Atmos Renderer is free. Unless you are specifically targeting the Sony ecosystem, Atmos is the pragmatic choice.
For music, it depends on the mix. A well-produced Atmos mix of an orchestral recording or a complex electronic track can be genuinely transformative. A hastily upmixed pop track may sound gimmicky or worse than the stereo version. For film and gaming, spatial audio is unambiguously beneficial, providing accurate sound localization that enhances immersion and narrative clarity.
# Downmix to stereo AAC, removing all spatial metadata
ffmpeg -i spatial_input.mp4 -ac 2 -c:a aac -b:a 256k \
-map_metadata -1 stereo_output.m4a
Spatial audio has matured from a cinema novelty to a mainstream technology available on devices most people already own. Dolby Atmos dominates the commercial landscape with broad platform support and robust production tools. Sony 360RA serves a niche within Sony's hardware ecosystem. Apple Spatial Audio adds head tracking and personalization on top of Atmos content. Ambisonics remains the standard for VR and 360 video.
For content creators, the practical advice is clear: if you are mixing music or film audio for commercial distribution, invest in learning Dolby Atmos. If you are working with VR or 360 video, Ambisonics is the standard. And regardless of format, always keep your original spatial masters, as converting between formats involves quality loss.
For everyday audio conversion tasks, including extracting audio from video, converting between codecs, and adjusting bitrates, the Audio Converter and Video Converter handle the most common workflows. For compressing large audio files to meet platform requirements, the Video Compressor supports audio-only compression as well.
Sarah Chen
Technical writer specializing in multimedia formats and digital workflows. Covers file conversion, video encoding, and document processing.