--- title: "ARRIRAW .arx workflow: How to handle legacy HDE sequences in post" author: "Cutsio Team" date: "2026-04-11" lastmod: "2026-05-13" category: "Storage & Performance" excerpt: "ARRIRAW/HDE .arx is a legacy CODEX HDE format, not a current Alexa 35 recording format. How it differs from .ari and MXF-wrapped ARRIRAW, and what to verify before cloud upload or DaVinci Resolve conform." tags: ["ARRI RAW","ARRIRAW","ARX","HDE","Alexa 35","Post Production","DIT Workflow"] --- ## What is ARRIRAW/HDE .arx and how does it differ from other ARRIRAW formats? ARRIRAW/HDE `.arx` is a legacy CODEX High Density Encoding workflow for ARRIRAW frame sequences, not a new in-camera ALEXA 35 recording format. ARRI documents `.arx` as HDE-encoded ARRIRAW frame sequences used for earlier camera models, while current ALEXA 35, ALEXA 35 Xtreme, and ALEXA 265 HDE workflows use MXF/HDE output from CODEX Device Manager or the ARRIRAW HDE Transcoder. The ARRIRAW family includes legacy `.ari` single-frame sequences, MXF-wrapped ARRIRAW, legacy `.arx` HDE frame sequences, and newer MXF/HDE files. Each serves a different workflow need and has different software support. | Property | .ari (Legacy) | .mxf (MXF-wrapped) | .arx (Legacy HDE Sequence) | | :--- | :--- | :--- | :--- | | Compression | Uncompressed | Uncompressed or HDE, depending on file | HDE lossless compression | | Frame storage | Single frame per file | All frames in one MXF | All frames in one ARX file | | Camera support | Earlier ARRIRAW workflows | Current MXF ARRIRAW/HDE workflows | Earlier camera models up to ALEXA Mini LF | | Raw parameter control | Full | Full | Full | | NLE support | Legacy (via ARRI SDK) | Broad current support | Verify ARRI/HDE support | | File management | Many small files | One file per clip | One file per clip | The practical takeaway: if `.arx` appears in a conform package, treat it as legacy HDE ARRIRAW and verify decoder support immediately. For ALEXA 35-class productions, expect MXF/ARRIRAW or MXF/HDE rather than `.arx` frame sequences. Working with raw camera footage? Check out [How to Build a Searchable Library From ARRIRAW, RED R3D, and ProRes Footage](/blog/how-to-build-searchable-library-from-arriraw-red-r3d-prores-footage). Streamline your workflow with [How to speed up video editing workflow 10x](/blog/how-to-speed-up-video-editing-workflow-10x). ## When should you use .arx instead of .mxf ARRIRAW? For new productions, `.arx` is usually not a format you choose on ALEXA 35-class cameras. It is more often something a post team receives from a legacy ARRIRAW/HDE workflow. The choice is normally between MXF/ARRIRAW, MXF/HDE, ARRICORE, or ProRes depending on the camera and post path. Use `.arx` only when: - The footage already comes from a legacy CODEX HDE `.arx` workflow - The post software stack has been verified to support `.arx` decoding - The DIT report and checksum manifest confirm the frame sequence is complete - The finishing vendor has tested a representative clip before conform Use MXF/HDE or MXF/ARRIRAW instead when: - The post house has not verified `.arx` support in its NLE and grading software - The production requires maximum compatibility across different post vendors - The conform workflow uses third-party tools that may not support `.arx` - The production is shooting on ALEXA 35, ALEXA 35 Xtreme, or ALEXA 265, where current HDE is MXF-based | Workflow Factor | .arx | .mxf | | :--- | :--- | :--- | | Storage savings | HDE reduction on legacy frame sequences | Baseline ARRIRAW or HDE reduction for MXF/HDE | | Camera compatibility | Legacy ARRIRAW/HDE workflows | Current ARRIRAW/HDE workflows | | NLE support | Check ARRI/HDE support | Broader current support | | DIT offload speed | Smaller than uncompressed ARRIRAW | Depends on HDE workflow | | Cloud upload time | Faster | Standard | | Conform complexity | Low (if supported) | Low | ## What are the known compatibility issues with .arx in post production? The .arx format has specific compatibility limitations that must be verified before production begins. The most important limitation: `.arx` support requires software that can decode CODEX HDE ARRIRAW frame sequences. Newer tools may focus on MXF/ARRIRAW and MXF/HDE instead, so support must be verified instead of assumed. | Application | .arx Support | Notes | | :--- | :--- | :--- | | DaVinci Resolve | Verify with current release and ARRI SDK | Test the exact frame sequence | | Avid Media Composer | Verify AMA/plugin support | Test before editorial handoff | | Adobe Premiere Pro | Verify ARRI/plugin support | Check current compatibility | | Baselight | Verify with Baselight release notes | Test before grade | | ARRI Reference Tool | Verify current version | Use as a first decode sanity check | | Final Cut Pro | Limited | May require transcode to ProRes | If a post application does not support `.arx`, test conversion through ARRI Reference Tool or another ARRI-supported workflow before editorial starts. Do not assume a transcode will preserve every metadata field until it has been checked. For cloud dailies workflows, verify that the dailies platform supports the exact `.arx` package before upload. Cutsio's enterprise raw ingestion add-on should be tested with a representative `.arx` sequence before production relies on it. ## How does .arx compare to HDE-compressed .mxf ARRIRAW? `.arx` is an HDE ARRIRAW sequence workflow. The comparison that matters for current productions is legacy `.arx` HDE sequences versus MXF/HDE files. | Property | .arx (Legacy HDE Sequence) | MXF/HDE | | :--- | :--- | :--- | | Compression type | HDE lossless compression | HDE lossless compression | | Applied when | During legacy CODEX HDE workflow | During offload/transcode workflow | | Camera support | Earlier camera models up to ALEXA Mini LF | ALEXA 35, ALEXA 35 Xtreme, ALEXA 265, and supported MXF workflows | | File structure | Frame sequence | One MXF clip | | NLE support | Verify ARRI/HDE support | Broader current support | | Workflow risk | Sequence completeness and decoder support | MXF metadata and decoder support | The practical difference: `.arx` sequences need sequence-aware handling, while MXF/HDE behaves more like the current MXF camera-original workflow. MXF/HDE is the safer choice for new ALEXA 35-class productions. For productions that want storage savings and maximum post compatibility, the recommended workflow is to record .mxf ARRIRAW in-camera and apply HDE during offload. This gives the 40% storage reduction with full NLE compatibility. ## How does Cutsio handle .arx files in the enterprise ingestion pipeline? Cutsio's enterprise raw ingestion add-on should be verified with a sample `.arx` sequence before production upload. Once support is confirmed for the package, `.arx` files can follow the same original-retention and review-asset workflow as other camera-original formats. The upload workflow: 1. DIT offloads .arx files from Alexa 35 Compact Drives 2. The .arx files are uploaded to Cutsio through the enterprise add-on 3. Cutsio verifies decode support for the uploaded `.arx` package 4. Streamable review assets are generated with the correct LogC-to-video color transform 5. The original .arx files remain attached for download and conform 6. Visual Intelligence indexes the generated review stream The online editor downloads the original .arx files for conform. If the NLE supports .arx natively, the files are imported directly. If the NLE does not support .arx, the editor can download the files and transcode to ProRes or DNxHR using the ARRI Reference Tool. ## How do you verify .arx support before production? Before committing to .arx as the acquisition format, run a compatibility test through the entire post pipeline. Test checklist: 1. Confirm whether the job is receiving legacy `.arx` HDE sequences or current MXF/HDE files 2. Offload or restore the complete sequence/package using the production copy tool 3. Open the `.arx` sequence or MXF/HDE file in ARRI Reference Tool to verify it decodes correctly 4. Import the sample into DaVinci Resolve, Avid Media Composer, Adobe Premiere Pro, or the actual finishing software 5. Verify that the color space, look metadata, and timecode are read correctly 6. Upload the sample package to Cutsio and verify the review stream 7. Download the package from Cutsio and verify the conform package 8. If any step fails, switch to MXF/ARRIRAW or MXF/HDE for new material where possible ## FAQ ### Is .arx visually lossless or mathematically lossless? `.arx` is an HDE ARRIRAW sequence format. HDE is ARRI/CODEX's lossless path for reducing ARRIRAW storage; verify the exact file type and tool support before calling the workflow approved. ### Can .arx files be converted to .mxf ARRIRAW in post? Use the current ARRI Reference Tool documentation to confirm available conversions for the exact `.arx` sample. Do not assume conversion support until the finishing vendor has tested it. ### Does .arx preserve ALF4 look metadata? Verify this with the actual sequence. Legacy `.arx` workflows can carry ARRIRAW metadata, but look-package behavior should be checked against ARRI Reference Tool output and the approved dailies reference. ### Which Alexa 35 recording modes support .arx? ALEXA 35-class HDE workflows are MXF-based. ARRI documents `.arx` HDE frame sequences as a legacy path for earlier camera models, while ALEXA 35, ALEXA 35 Xtreme, and ALEXA 265 use MXF/ARRIRAW and MXF/HDE workflows. ### Should I use .arx or HDE for cloud dailies? For current ALEXA 35-class cloud dailies, use MXF/ARRIRAW or MXF/HDE unless the production has a specific legacy `.arx` package to ingest. Use `.arx` only if the entire post pipeline has been verified to support it.

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