IMF Packages Explained
Updated
The Interoperable Master Format, from the SMPTE ST 2067 documents: what is in a package, how CPLs and supplemental packages make versions, what Application #2E allows, and who asks for it.
What IMF Is
IMF is a master made of parts. Instead of one flattened file per version, a package holds the picture, each audio layout and each subtitle file as separate track files, and a playlist (the CPL) for each version that says which parts to play. A French dub, a textless version or a censored cut is a new CPL plus whatever essence is new; the rest is shared. That is why streamers that sell one title in dozens of languages adopted it.
The standards are SMPTE's ST 2067 family. As of October 2026 the full texts can be read free at pub.smpte.org.
What's Inside a Package
An Interoperable Master Package (IMP) is one Packing List and every asset it lists (ST 2067-2). On disk that is a folder like this:
| File | Standard | What it does |
|---|---|---|
| ASSETMAP.xml | SMPTE ST 429-9 | Maps every asset's UUID to a file path. It is the first thing an ingest system reads. |
| Packing List (PKL) | ST 429-8, as modified by ST 2067-2 | Lists the assets in this package by UUID, with a hash of each, so the receiver can check every file arrived intact. |
| Composition Playlist (CPL) | ST 2067-3 | One version of the title: which track files play, in what order, with which in and out points. A package can hold several CPLs. |
| Track files (.mxf) | ST 2067-5 (OP1a MXF) | The essence. Each track file holds one kind: picture, one audio soundfield group (a 5.1 or a stereo), or one timed text document. |
| Output Profile List (OPL) | ST 2067-100 | Optional. Describes how to turn a CPL into a deliverable, such as a scale, crop or color transform. |
| VOLINDEX.xml | ST 429-9 (deprecated) | A leftover from D-Cinema. ST 429-9:2014 says the Volume Index is not used; Netflix says it may be present but is not required. |
Everything is referenced by UUID, not filename, so renaming a track file doesn't break anything as long as the Asset Map is updated. Once a system has ingested the package, it no longer needs the PKL or Asset Map; the CPLs and track files are the master.
Versions and Supplemental Packages
ST 2067-2 calls a package that holds everything a CPL needs a complete IMP, and one that relies on essence delivered earlier an incomplete IMP. In delivery specs the incomplete kind is usually called a supplemental package. Typical uses:
- • Original version: a complete IMP with picture, the original-language mix and a CPL
- • A dub: a new CPL plus the Spanish audio track file, pointing at the picture already delivered
- • Textless: a CPL that swaps in textless picture inserts, cut to cut, over the texted shots. Netflix asks for textless as a supplemental IMF built on the last approved texted package.
- • A fix: a new CPL and a corrected track file or insert, instead of re-sending the whole film
IMF Applications
The core documents define the package; an Application sets the codec and image limits. Each CPL names its Application. The original App #2 (ST 2067-20, HD only) is withdrawn; App #2E replaced it.
| Application | Document | Essence | Used for |
|---|---|---|---|
| App #2E | ST 2067-21:2026 | JPEG 2000 (and HTJ2K since 2023), PCM audio | Studio and streaming masters. The one most specs ask for. |
| App #4 | ST 2067-40:2021 | Lossless JPEG 2000, up to 16-bit | Cinema mezzanine and preservation |
| App #5 | ST 2067-50:2018 | ACES (ST 2065-1) image frames | Archive of ACES masters |
| App #6 | ST 2067-60:2023 | AVC (H.264) | UHDTV program workflows |
| VC-3 / VC-6 | ST 2067-70 and -71 (2024) | VC-3 (the codec behind DNxHD), VC-6 | Packages with picture in those codecs |
| ProRes | RDD 45:2022, RDD 59-1:2022 (DPP) | Apple ProRes | App 2E-style packages with ProRes picture |
Sources: SMPTE ST 2067 documents and the IMF User Group explainer
Application #2E in Practice
App #2E (ST 2067-21) is the one in most delivery specs. The current edition was approved in July 2026; the 2023 edition added HTJ2K, and the 2020 amendment added HLG. Delivery specs name the edition they accept: Netflix, for example, lists the 2016, 2020 and 2023 editions.
- Picture
- One JPEG 2000 codestream per frame, using the Broadcast or IMF profiles; HTJ2K (ISO/IEC 15444-15) allowed since the 2023 edition
- Frame size
- Up to 4096×3112 in the 2023 edition. The 2026 edition adds 8K: up to 7680×4320 for 4:2:2 Y′CbCr and 8192×6224 for 4:4:4 RGB.
- Frame rates
- 23.976, 24, 25, 29.97, 30, 50, 59.94 and 60 progressive; 120 in RGB 4:4:4 only; interlaced 25, 29.97 and 30 at HD only
- Color
- BT.709, BT.2020 SDR, BT.2020 HLG, BT.2020 PQ, and P3-D65 PQ (RGB only), 8 to 16 bits depending on the combination
- Audio
- 48 or 96 kHz, 24-bit PCM, each channel labeled with SMPTE multichannel audio labels (ST 377-4)
- Timed text
- IMSC 1.1 Text or Image profile, one document per track file
- Segments
- At 29.97 and 59.94, each segment must be a multiple of 5 frames, so it holds a whole number of audio samples
Sources: ST 2067-21 (2023 and 2026 editions), ST 2067-2:2020 for audio and timed text
Picking a JPEG 2000 Level
The IMF JPEG 2000 profiles are graded by Mainlevel (how many samples a second the decoder must handle) and Sublevel (the maximum bit rate). ST 2067-21 gives the sample rate formula in an informative annex, and recommends about 5% headroom so a 24 fps master can play at 25 without changing level.
MSamples/s = width × height × fps × components ÷ 1,000,000Components is 3 for 4:4:4 and 2 for 4:2:2. Mainlevel limits from ST 2067-21 Annex E: ML4 260, ML5 520, ML6 1,200, ML7 2,400 MSamples/s. Sublevel caps: SL2 400, SL3 800, SL4 1,600 Mbit/s.
Example: UHD RGB 4:4:4 at 30 fps
- Calculation:
- 3840 × 2160 × 30 × 3 ÷ 1,000,000
- Result:
- 746.5 MSamples/s: Mainlevel 6. At 60 fps it is 1,493: Mainlevel 7.
That is why Netflix specifies Mainlevel 6 Sublevel 3 (800 Mbit/s) for UHD up to 30 fps and Mainlevel 7 Sublevel 4 (1,600 Mbit/s) above it; HD 4:4:4 is 186.6 MSamples/s at 30 fps, inside Mainlevel 4. The Sublevel cap is also the worst case for storage: 800 Mbit/s for an hour is 360 GB of picture. Size real encodes in Data & Storage or the free bitrate calculator in your browser.
Who Asks for IMF
- • Netflix requires an App #2E IMF for branded titles, with no timed text inside the package and one audio language per CPL. See the Netflix delivery specs guide.
- • Apple's public Video and Audio Asset Guide specifies ProRes QuickTime files for the Apple TV app and has no IMF profile. See Apple TV and Prime Video delivery.
- • Disney publishes its lossy "IMF-D" distribution package on its Media Tech Specs site. As of its IMF-D v1.13.2 page (dated 2021): App #2E (ST 2067-21:2020), UHD 3840×2160 RGB 4:4:4 full range, JPEG 2000 Mainlevel 6 Sublevel 4 (1,600 Mbit/s maximum), 12-bit PQ in a BT.2020 container for HDR, 5.1 plus stereo at 48 kHz, 24-bit, and the program starting 1 second into the file.
- • Amazon: its public Prime Video pages ask for ProRes mezzanine files; we found no public IMF requirement.
- • UK and North American broadcasters: the DPP registered a ProRes IMF application with SMPTE (RDD 59-1:2022). Broadcasters still mostly take file masters; see the broadcast deliverables checklist.
Making and Checking a Package
- 1
Finish and conform
Lock picture, sound and a textless set of the shots that carry titles. Know your deliverable list before you start: languages, HDR or SDR, and which audio layouts.
- 2
Encode the track files
Picture to JPEG 2000 at the profile your spec names, audio to 24-bit PCM with channel labels. Each soundfield group (5.1, stereo, M&E) becomes its own track file.
- 3
Build the CPL and package
Write the CPL for the original version, then the PKL and Asset Map. A mastering tool does this for you; Apple's Compressor is one of the tools that can build IMF packages.
- 4
Validate
Run a validator before anything leaves. Netflix's Photon is open source; the IMF User Group lists others. Then check the composition plays, frame-accurate, in a player.
- 5
Version with supplemental packages
For a dub, a textless version or a fixed shot, deliver a new CPL plus only the new track files. It points back at essence already delivered.
Tools: Netflix Photon (Apache-2.0), IMF User Group open-source list, IMF in Apple Compressor
Before You Deliver an IMF
- Confirm the Application and edition the spec names (App #2E 2016, 2020, 2023 or 2026)
- Encode at the JPEG 2000 profile, Mainlevel and Sublevel the spec gives, not just "J2K"
- Label every audio channel; one soundfield group per audio track file
- Trim 29.97 and 59.94 segments to multiples of 5 frames
- Check whether the recipient wants timed text inside the IMF or as separate files
- Validate the package, then watch the CPL through before you upload
An IMF for a feature runs to hundreds of gigabytes. Work out the transfer time in Upload Time, or the free upload time calculator in your browser, before you book the delivery slot.
Questions
What is an IMF package?
An Interoperable Master Package is a master made of parts, defined by SMPTE's ST 2067 documents: an Asset Map, a Packing List, one or more Composition Playlists, and MXF track files holding the picture, each audio layout and each timed text file separately. Each CPL describes one version of the title.
What is the difference between a CPL and a PKL?
The Composition Playlist (CPL, ST 2067-3) is one version of the title: which track files play, in what order and with which in and out points. The Packing List (PKL) lists the assets delivered in the package by UUID, with a hash of each, so the receiver can check every file arrived intact.
What is IMF Application 2E?
Application #2E, SMPTE ST 2067-21, is the IMF application most delivery specs ask for: JPEG 2000 picture (HTJ2K allowed since the 2023 edition) with PCM audio. The 2023 edition goes up to 4096×3112; the 2026 edition adds 8K. The original Application #2 is withdrawn.
What is a supplemental IMF package?
A package that relies on essence delivered earlier: a new CPL plus only the new track files, such as a dubbed audio track, textless inserts or a corrected shot. SMPTE calls it an incomplete IMP; delivery specs usually call it supplemental.
Is an IMF the same as a DCP?
No. Both use an Asset Map, a Packing List, a playlist and MXF track files, but a DCP is a distribution format for cinema servers, while an IMF is a mastering format used to make other deliverables.
Which streamers require IMF?
Netflix requires an App #2E IMF for branded titles, and Disney publishes an App #2E distribution package on its Media Tech Specs site. Apple's public asset guide specifies ProRes QuickTime files, and Amazon's public Prime Video pages ask for ProRes mezzanine files.