ADM to IAMF Exporting

Pro

ADM to IAMF exporting is an Orbit Pro feature.

Convert your Dolby Atmos ADM BWF master to an IAMF file you can deliver to streaming platforms that play IAMF natively. If you've never made an IAMF before, this page walks you through it — the defaults are tuned to work for most cases, and there's a friendly first-export path below before any of the deeper options.

For background on what IAMF is and why you might want to deliver in it, see IAMF Basics.

Before you start

You need:

• Orbit Pro (export is Pro-gated; preview / playback of IAMF works on standard Orbit too).
• An open ADM BWF file in Orbit. Load the .wav you want to convert via File → Open File… as you would for a regular QC pass.
• A few minutes for the export to run. Encoding times depend on length and codec — Opus is fast, FLAC and LPCM scale with file size.

There's no separate IAMF authoring step. Orbit reads the ADM metadata you already have (beds, objects, automation, HOA groups) and re-encodes it into an IAMF file that carries the same spatial structure.

Your first export (the friendly path)

If this is your first IAMF and you just want to ship something good, ignore every option except these:

1. File → Export → IAMF… (or whatever menu path your build exposes — the export action is also reachable from the export button in the header).
2. The export sheet opens. Leave Codec on Opus and Quality on Studio.
3. Leave the Container set to whatever the default is — .iamf for raw, .mp4 if you want to bundle video.
4. Click Export IAMF.
5. Pick a save location.
6. Wait for the progress overlay to finish. A summary sheet appears showing the export's conformance checks and per-layout loudness.

That's a complete, well-formed IAMF file. Most platforms accept it as-is.

The rest of this page explains what every option does, so you know when (and whether) to deviate.

Opening the export sheet

The sheet is a full-window overlay rather than a system dialog. Cancel either by clicking Cancel in its bottom bar or by pressing Escape. Closing without exporting preserves your settings — your codec / quality / object-selection choices are remembered for the next session, so you don't have to re-tune them every time.

The sheet has three main areas:

• Left — the codec, quality, profile, and container settings.
• Centre — object selection (decide which ADM objects ship as discrete IAMF object elements vs. get pre-mixed into the bed).
• Right — preview, mix-presentation summary, and (when relevant) scalable-layer authoring.

You can audition any setting from inside the sheet — the Preview card has its own transport so you don't have to dismiss the sheet to listen.

Codec

IAMF supports four codecs. Pick based on the delivery target:

Codec	When to use	Notes
Opus	Streaming delivery, online video, anywhere you want a small file	Default. Lossy, perceptually transparent at Studio quality on most material.
FLAC	Archival, lossless intermediates, contribution feeds	Lossless. Files are larger than Opus but smaller than LPCM.
AAC-LC	Apple-ecosystem deliveries, legacy compatibility	Lossy. Available on macOS via AudioToolbox.
LPCM	Reference / debugging / round-tripping to another tool	Lossless and uncompressed. Largest files.

Default: Opus.

Quality (Opus and AAC-LC)

Opus and AAC-LC are lossy codecs and need a bitrate. Orbit hides the raw bps behind three named presets:

• Streaming — 48 kbps per channel. Smallest acceptable file. Audible compression on dense music; fine for dialogue / FX-heavy content.
• Studio — 96 kbps per channel. The default. Xiph's "transparent music" target — most listeners can't tell from the source on most material.
• Archive — 128 kbps per channel. Diminishing returns past this point on Opus; switch to FLAC instead if you need genuine archival quality.

The picker shows both the per-channel rate and the total kbps for your current export so you can see the actual cost. Per-channel matters because IAMF coupled-stereo substreams get 2× the per-channel rate, mono substreams get 1×, and a 7.1.4 export with several objects can reach a substantial total.

TIP

Studio is the right answer in almost every case. Streaming is for when you're cost-constrained on bandwidth and the material can absorb compression; Archive is for when you specifically want a higher floor and don't mind the file size. Most real deliveries are Studio.

Bit depth (LPCM)

When the codec is LPCM, choose between 16-bit and 24-bit. 24-bit is the default — it matches the precision Orbit's engine carries internally and the precision you'd get from an ADM master.

FLAC compression level (FLAC)

When the codec is FLAC, the compression level slider runs 0–8. 5 is the default and is the FLAC reference codec's own default — past 5, you trade noticeable encode time for diminishing file-size returns. Decode time is the same regardless of compression level, so listeners aren't affected by your choice.

Profile

IAMF v2.0 defines three profiles, each with a different element budget:

• Simple — at most 1 audio element. The basic profile, suitable for stereo / mono / single-element deliveries. Accepts every audio-element type (channel-based, object-based, and HOA Scene-Based) so long as the element count stays at one.
• Base — multiple elements with a moderate channel budget. The right choice for most multi-element streaming mixes.
• Base-Enhanced — the largest budget. Default in Orbit. Most useful for element-heavy mixes that exceed Base's limits.

Pick Simple or Base for most platforms today

Orbit's default is Base-Enhanced, but most current IAMF decoders (including YouTube and the IAMF Binaural Web Demo) only accept Simple or Base. If you're delivering to a platform today, change the profile picker to Simple or Base before exporting — a Base-Enhanced file will fail to decode on most real delivery targets even though it's spec-valid.

HOA Scene-Based content is not gated to Base-Enhanced — it works fine in Simple (single element) and Base. Pick whichever matches your element count.

Quick guide:

• Single element (one bed, one object, or one HOA scene on its own) → Simple.
• Multiple elements but a typical streaming budget (e.g. a 7.1.4 bed plus a handful of objects, or a HOA scene plus a stereo bed) → Base.
• Element-heavy work that exceeds Base's per-profile limits → Base-Enhanced, with the caveat that the file may not decode on most current platforms.

Container

Two options:

• Standalone (.iamf) — raw IAMF bitstream (an OBU sequence). Smallest and simplest; the right choice for audio-only delivery.
• ISO-BMFF (.mp4) — IAMF wrapped in an MP4 container, optionally muxed with video. The right choice when you're delivering picture-and-sound, when your delivery platform expects MP4, or when you want to attach metadata (title, language, etc.) that ISO-BMFF carries.

Default: Standalone. Switch to ISO-BMFF if you need video, or if your downstream tooling specifically wants .mp4.

Object selection

The middle of the sheet shows every ADM object in your file with a checkbox. Each object can be:

• Kept (checked) — encoded as a discrete IAMF Object-Based audio element with its own automation and per-frame position. The decoder pans it at playback time. Best for content that needs to remain dynamic (a moving sound effect, a voice walking around the listener).
• Merged (unchecked) — pre-mixed into the bed (or into the rendered ChannelBased element when the source has no bed). The position and automation are baked in at the export stage. Saves bitrate at the cost of dynamic flexibility.

The default is keep all — every object stays discrete. Merging objects is a deliberate choice you make when you're hitting an element budget, when you want a smaller file, or when an object's automation is so simple (or so static) that there's no value in keeping it dynamic.

The sheet shows a counter — N kept, M merged into bed — at the top of the object grid so you can see the impact at a glance.

TIP

For dialogue-driven content, kept-object count rarely needs to exceed three or four. For sound design / VFX-heavy material with a lot of moving sources, you'll typically keep more.

Scalable layers (Opus, channel-based only)

By default, Opus exports of channel-based content emit a single audio layer at the source's top loudspeaker layout (e.g. 7.1.4). The Scalable Layers card on the right of the sheet lets you author a ladder of layers instead — multiple progressively-richer layouts the decoder can pick from based on the playback environment.

A typical ladder would be Stereo → 5.1 → 7.1.4. A stereo decoder pulls just the bottom layer; a 7.1.4 decoder pulls all three and reconstructs the full mix.

INFO

Scalable layer authoring is only meaningful for ChannelBased Audio Elements coded with Opus (per IAMF v2.0 §3.6.4). Object-Based and Scene-Based (HOA) elements always ship as a single layer regardless. The Scalable Layers card is hidden when the source has no bed, when the codec isn't Opus, or when there's no rendered ChannelBased element to author against.

Default: off (single layer). Turn on for streaming targets that benefit from layer adaptation (e.g. heterogeneous client environments).

Binaural target layout

IAMF Mix Presentations can include a Binaural target layout, which tells downstream decoders that the file has been authored with binaural rendering in mind and gives them HRTF-measured loudness for the binaural feed. Orbit Pro adds this layout by default — it's spec-valid, it improves binaural playback consistency on platforms that respect it, and it costs essentially nothing in encode time or file size.

Toggle off only if your delivery target specifically requires no binaural metadata.

Rendering to a ChannelBased element (HOA-only sources)

If your source is HOA-only (Scene-Based content with no beds and no objects), Orbit can optionally render a ChannelBased Audio Element from the HOA into a chosen loudspeaker layout (Stereo, 5.1, 5.1.4, 7.1.4, etc.) and include it alongside the Scene-Based element. This produces a hybrid file that decodes well on both HOA-aware and channel-only players.

When the Render to ChannelBased option is on:

• Pick the target layout from the picker (default 7.1.4).
• Optionally enable Fold Ambisonics into Rendered to replace the Scene-Based elements with the rendered channel-based one, rather than ship both. Use this when your delivery target is channel-only and you don't need the HOA in the file.

For sources that already have a bed and / or objects, this section doesn't apply — the existing channel-based element is encoded directly.

Pan-law

Object panning at export time uses a pan law — the same one the live monitor uses, by default. Two overrides are available:

• Match Session (default) — follow whatever pan law you've set in Spatial preferences. Easy when you're QC-ing in the same configuration you'll deliver in.
• VBAP — force classical Vector-Base Amplitude Panning regardless of session.
• LBAP (Dolby-like) — force Layer-Based Amplitude Panning. Matches Dolby's 7.1.2 → 7.1.4 upmix behaviour. The right choice when you want a distribution-grade encode regardless of how you happen to be monitoring.

TIP

If you're delivering to a platform that re-renders the IAMF at playback (most do), the export pan-law mainly affects how merged objects sound when an element-based player can't decode the discrete objects. LBAP is the safe default for distribution; Match Session is fine for personal / QC-driven work.

Video (ISO-BMFF only)

When the container is ISO-BMFF (.mp4) and your session has a video edit list attached, the sheet exposes video options:

• Include Video — toggle the video track in or out of the muxed MP4.
• Codec — HEVC (default) or H.264. HEVC produces smaller files at the same quality; H.264 has broader compatibility.
• Quality — Low / Medium / High (default) / Lossless. The standard quality / size trade-off.
• Resolution — Auto (match source) / 1080p / 720p / 480p. Use Auto unless you need a downscale.

These options are hidden when the container is Standalone (no MP4 to mux into).

Running the export

When you click Export IAMF:

1. The export sheet dismisses.
2. A save panel asks for a location and filename.
3. After you confirm, a progress overlay takes over showing each stage (preparing, rendering video if applicable, encoding audio, writing container, finalising).
4. You can cancel mid-export with the Cancel button. Cancellation stops cleanly and removes the partial output.
5. When the export completes, a summary sheet appears.

The export summary

The summary covers:

• File size and duration of the output.
• Codec, profile, container chosen.
• Per-layout loudness measurements written into the file (integrated LUFS and true-peak dBTP at every Mix Presentation target). These are part of what a compliant IAMF file must include — broadcasters and streaming platforms read them.
• Conformance checks — a list of automated validations the encoder ran (descriptor structure, OBU sequencing, codec config validity, mix presentation validity, etc.). Anything failing here means the file probably won't decode correctly on a strict decoder; investigate before shipping.

If anything fails or warns, the summary tells you what — there's no need to dig through logs.

Known limitations

A few things to be aware of as of this writing:

• Single Mix Presentation per export. Orbit writes one Mix Presentation per IAMF file, derived from the source ADM programme. Authoring multiple Mix Presentations on export (so a single file carries, e.g. a 7.1.4 mix and a stereo mix and a language variant) is planned but not yet shipping.
• Expanded loudspeaker layouts. IAMF v2.0 adds expanded layouts (9.1.6, 7.1.5.4, etc.). Orbit does not currently support these layouts for either decode or encode. Exports use the standard set (Stereo, 5.1, 5.1.x, 7.1, 7.1.x, 3.1.2), and IAMF files that declare expanded layouts won't play back in Orbit either.
• Per-object loudness measurements. Orbit measures per-Mix-Presentation loudness; per-individual-element loudness in the IAMF Mix descriptor (an optional spec field) is not currently emitted.

If any of these matter for your delivery, get in touch.

See also

• IAMF Basics — what IAMF is, the audio-element types, mix presentations, the codec landscape.
• Spatial preferences — pan law, height weighting, and the IAMF playback options that affect how Orbit renders the source mix you're about to export.
• Sessions — when you're exporting from a session, the session's video edit list is what feeds the ISO-BMFF video track.