# The Immersive Audio Client Handoff Checklist: What to Send and How to Check It > What to send a client, label or platform with an immersive mix: ADM master, Eclipsa Audio, stereo, binaural, stems, loudness report and notes, plus a free way to check every file first. Web page: https://spatial9.ai/blog/immersive-audio-client-handoff-checklist Author: Spatial9 Team Published: 2026-11-03. Updated: 2026-11-03. ## Key takeaways - A complete immersive handoff usually includes an ADM BWF master, an Eclipsa Audio file where YouTube is a target, stereo, binaural, stems, a loudness report and a notes document. - Check that every ADM master still carries its chna and axml chunks; an editor that drops them leaves ordinary multichannel audio with no scene. - The stereo version must line up with the immersive master. Apple requires Dolby Atmos files to be conformed and synced to the stereo reference. - Dolby and UMG publish -18 LKFS integrated and -1 dBTP true peak as maximums for Dolby Atmos music, measured with ITU-R BS.1770. - Write the channel order, sample rate, frame rate, ISRCs and layout in a plain notes file, because embedded metadata is easy to lose. - The free Spatial9 file checker inspects, plays and loudness-checks each file in the browser before handoff, without uploading it. Short answer: a complete immersive handoff usually contains seven things: the ADM BWF master, the Eclipsa Audio file (.iamf or .mp4) if YouTube is a target, a stereo version, a binaural headphone render, stems, a loudness and true-peak report, and a short notes document that states the channel order, sample rate, frame rate and naming scheme. Check every file before it leaves your studio. The free file checker does that in your browser, without uploading anything. Most rejected deliveries are not bad mixes. They are good mixes sent with a missing chunk, the wrong sample rate, an unexplained track order or a stereo file that no longer lines up with the immersive one. This checklist is the list we would want to receive ourselves. Use it for clients, labels, distributors and platforms, and adapt it to the spec each one gives you. ## The handoff package at a glance | Deliverable | Typical format | Who needs it | Check before sending | | Immersive master | ADM BWF (BW64), 24-bit PCM | Label, distributor, archive | chna and axml present, objects positioned | | Eclipsa Audio | .iamf, or .mp4 with an IAMF track | YouTube, client review | Plays, correct layout, 48 kHz | | Stereo | 2-channel WAV | Every platform | Same length and start as the master | | Binaural | 2-channel WAV | Headphone review, social | Labelled as binaural, not stereo | | Stems | Mono or multichannel WAV | Remix, archive, edits | Same length, same start, named clearly | | QC report | Plain text or PDF | Client, label QC | Loudness, true peak, clipping per file | | Notes | Plain text or PDF | Everyone | Channel order, rates, versions, contacts | ## 1. The ADM BWF master The ADM BWF is the file that carries the whole scene: beds, objects and how they move. It is a multichannel WAV with two extra chunks. The chna chunk maps tracks to IDs and the axml chunk holds the scene description written in the Audio Definition Model, ITU-R BS.2076. ITU-R BS.2088 defines the BW64 container that lets the file grow past 4 GB. Our guide to ADM BWF files covers the basics, and Inside an ADM WAV file walks through both chunks. Before you send it, confirm: - Both chunks survived. Editors that do not understand ADM can re-save a WAV without chna and axml. The file still plays, but the scene is gone. - The rate and depth match the spec. Dolby's music delivery playbook asks for 24-bit PCM at 48 kHz, and suggests keeping a 96 kHz master for archive if you worked at that rate. UMG's published Dolby Atmos spec accepts 96 kHz only when the mix was created natively at 96 kHz. - The start is clean. Dolby's playbook advises against silence at the start of a music mix, and UMG lists first frame of action as prohibited and the duration as matched to the stereo asset. - Binaural settings were made on purpose. Dolby asks for each bed and object to have a binaural render mode, and UMG flags masters where every assignment was left at its default. ## 2. The Eclipsa Audio file Eclipsa Audio is built on IAMF, the Immersive Audio Model and Formats specification from the Alliance for Open Media. The spec defines both a standalone IAMF bitstream and how to carry IAMF inside an MP4 file, so you may deliver either a .iamf or an .mp4. - For YouTube, send a video MP4. YouTube's recommended upload settings list Eclipsa Audio as an audio codec, with "Stereo + Eclipsa Audio" as the channel option, 48 kHz audio, an MP4 container with no edit lists and the moov atom at the front. YouTube suggests 128 kbps per channel for Eclipsa Audio. - For review, add a standalone file or a binaural render. Not every client can play IAMF. A binaural WAV lets them hear the immersive mix on any headphones. - State the layout. Write down the channel layout or ambisonic order you used, and which mix presentation is the default. If the immersive mix began life as a Dolby Atmos ADM master, the free ADM to Eclipsa converter creates the Eclipsa Audio file from it. Our Eclipsa Audio for YouTube guide covers the upload itself. ## 3. The stereo version Every platform still needs stereo, and most listeners will hear it. Decide, and write down, which of two things you are sending: - A dedicated stereo mix, mixed and mastered on its own. Labels usually treat this as the main release master. - A fold-down rendered from the immersive master. ITU-R BS.775 gives standard coefficients for reducing a 5.1 programme to stereo, and immersive renderers apply their own downmix rules. Either way, the stereo file must line up with the immersive one. Apple's delivery guidance says Dolby Atmos files must be conformed and synced to the stereo reference for the same project. Check start time, length and edit points before you send. ## 4. The binaural render A binaural file is two channels rendered for headphones. It is not a speaker mix, and it is not an immersive file: the space is baked into the left and right signals. Label it clearly, for example with BIN in the file name, so nobody masters it as stereo or uploads it as the main version. For the difference between the two, see binaural vs spatial audio. ## 5. Stems Stems let a client edit, remix, re-version or archive without returning to your session. Agree on the groups in advance: drums, bass, music, vocals, effects and so on. Every stem should: - start at the same timecode as the master and run for exactly the same length; - share the master's sample rate and bit depth; - say in its name whether it is mono, stereo or multichannel, and in what layout; - be printed without master bus processing, unless the client asked for processed stems. ## 6. The loudness and true-peak report Measure every deliverable, not just the master. The method in almost every spec is ITU-R BS.1770, which defines integrated loudness and true peak. Targets differ by destination: | Destination | Published target | | Dolby Atmos music (Dolby playbook, UMG spec) | Integrated loudness at or below -18 LKFS, true peak at or below -1 dBTP | | European broadcast (EBU R 128) | -23 LUFS integrated, -1 dBTP maximum true peak | | Your client or label | Whatever their own spec says, which overrides general guidance | The report should list, per file: integrated loudness, maximum true peak, any clipped samples and the tool used. UMG's spec adds that a track should not fall below -31 LKFS, measured on a 5.1 downmix. ## 7. Naming, channel order and sample rate A consistent naming scheme answers most questions before they are asked. One pattern that works: ```text Artist_Title_Version_Format_Rate_Bit.ext Nova_Lights_Main_ADM_48k_24b.wav Nova_Lights_Main_IAMF_48k.mp4 Nova_Lights_Main_ST_48k_24b.wav Nova_Lights_Main_BIN_48k_24b.wav Nova_Lights_Main_STEM-Vox_48k_24b.wav ``` Then state the channel order in the notes, even when you think it is obvious. In WAV files the order follows the channel mask defined by Microsoft's WAVE_FORMAT_EXTENSIBLE: front left, front right, centre, LFE, back left, back right and onward. Some post-production tools use a different track order, so a six-track file with no mask and no notes forces the receiver to guess. For ADM masters, speaker labels follow ITU-R BS.2051, such as M+030 for front left. Keep one sample rate across the package unless the spec asks otherwise. YouTube expects 48 kHz audio, and Dolby's playbook asks for 48 kHz music masters. ## 8. Metadata and the notes document Metadata inside files is easy to lose, so put the essentials in a plain notes file as well: - title, artist, version name and mix date; - ISRCs. Apple requires a unique secondary ISRC for Dolby Atmos deliveries; - sample rate, bit depth, frame rate and start timecode; - channel order or ADM layout, and the Eclipsa Audio layout or ambisonic order; - loudness figures and the measurement tool; - what is not in the package, and who to contact with questions. ## Check every file before handoff Run each file through the free Spatial9 file checker before you send it. It reads more than 50 formats in your browser, and nothing is uploaded. It shows whether an ADM master still has its chna and axml chunks, plays ADM, Dolby and surround files in a virtual 7.1.4 room, lets you compare Eclipsa Audio and ambisonic files in stereo and binaural, tells you whether a file is really stereo, mono or video, and runs a BS.1770 loudness, true-peak and clipping check. For what each result means, see Is this file really immersive? Good to know: the checker is a preview and QC aid, not a certified loudness meter or a platform validator. A file that passes can still be rejected for a spec item it does not test, such as label metadata. Always confirm the final spec with whoever receives the files. ## What this checklist does not cover This is a general starting point for music and video deliveries. It does not replace a label, distributor or broadcaster specification, and it does not cover picture deliverables, captions or contracts. Where a spec and this list disagree, follow the spec. ## Frequently asked questions ### Do I need to send both an ADM master and an Eclipsa Audio file? Only if the client publishes to both kinds of platform. Apple Music and other Dolby Atmos services take the ADM master through their delivery chain. YouTube takes Eclipsa Audio inside a video MP4. The ADM master is also the best source for any future version, so it belongs in the archive either way. ### Is a binaural file the same as a stereo master? No. Both have two channels, but a binaural file is rendered for headphones and can sound odd on speakers. Send both, and label them so they cannot be confused. ### Which loudness target should I use? The one in your client's spec. For Dolby Atmos music, Dolby and labels such as UMG publish -18 LKFS integrated and -1 dBTP true peak as maximums. Broadcast work in Europe usually follows EBU R 128. ### How can I check a file without the original software? Open it in the free file checker. It reads the structure, plays immersive files in a 7.1.4 room and runs a loudness check on your own device. ## Sources - ITU-R BS.2076: Audio Definition Model, International Telecommunication Union. - ITU-R BS.2088: Long-form file format for the international exchange of audio programme materials with metadata (BW64), International Telecommunication Union. - ITU-R BS.1770: Algorithms to measure audio programme loudness and true-peak audio level, International Telecommunication Union. - ITU-R BS.775: Multichannel stereophonic sound system with and without accompanying picture, International Telecommunication Union. - ITU-R BS.2051: Advanced sound system for programme production, International Telecommunication Union. - EBU R 128: Loudness normalisation and permitted maximum level of audio signals, European Broadcasting Union. - Immersive Audio Model and Formats (IAMF) specification, Alliance for Open Media. - YouTube recommended upload encoding settings, YouTube Help. - Delivering Dolby Atmos audio, Apple Music Provider Support. - Dolby Atmos Music Delivery Playbook, Dolby Laboratories. - Dolby Atmos Audio Servicing Asset Specifications, UMG Content Guide. - WAVEFORMATEXTENSIBLE structure, Microsoft Learn. ## Hand off with confidence A clean package saves days of back and forth. Spatial9 turns stereo tracks and ADM masters into Eclipsa Audio for YouTube, and the file checker is free for every file you send. Dolby and Dolby Atmos are trademarks of Dolby Laboratories. Spatial9 is not affiliated with or endorsed by Dolby Laboratories.