Cutsio Blog

ARRIRAW Container Guide: .ari vs .mxf vs .arx for Alexa 35, Mini LF, and SXT Workflows

Understand the difference between .ari, .mxf, and .arx ARRIRAW containers — which Alexa cameras produce each format, how file sizes compare, and what post-production workflows each format enables.

What are the three ARRIRAW container formats?

ARRIRAW exists in three container formats — .ari, .mxf, and .arx — each tied to specific Alexa camera models and production eras. The .ari container is the legacy format from Alexa SXT and earlier cameras. The .mxf container is the modern wrapper for ARRIRAW from Alexa Mini LF and Alexa 35. The .arx container is ARRI RAW Xpress, a compressed ARRIRAW format exclusive to the Alexa 35.

| Container | Full Name | Camera Models | First Introduced | Compression |

| :--- | :--- | :--- | :--- | :--- |

| .ari | ARRIRAW Classic | Alexa Classic, Alexa Plus, Alexa XT, Alexa SXT, Alexa Mini (original) | 2010 | Uncompressed or lightly compressed |

| .mxf | MXF-Wrapped ARRIRAW | Alexa Mini LF, Alexa 35 | 2018 (Mini LF) | Uncompressed |

| .arx | ARRI RAW Xpress | Alexa 35 only | 2022 | Visually lossless compression (~40–50% smaller) |

The container format determines which software can read the files, how much storage each minute of footage consumes, and what metadata is available in the post pipeline. A DIT, assistant editor, or post supervisor who understands the differences can diagnose compatibility issues, plan storage requirements, and build a pipeline that matches the camera fleet.

Which Alexa cameras produce each ARRIRAW container?

Alexa SXT and earlier — .ari

The .ari container is the original ARRIRAW wrapper. It is produced by the Alexa Classic (2010), Alexa Plus, Alexa XT, Alexa SXT, and the original Alexa Mini. The .ari file contains the sensor's Bayer pattern data wrapped in ARRI's proprietary container format with embedded metadata including reel name, scene, take, ISO, white balance, and color space.

Key characteristics of .ari files:

• Resolution: Up to 3.4K (Alexa SXT) or 2.8K (Alexa Classic)
• Color science: LogC (the original LogC curve, later updated to LogC3 on SXT)
• File size: Approximately 2.5–3.0 GB per minute at 3.4K
• Debayering: Required — no browser or consumer player can decode .ari natively
• Software support: DaVinci Resolve, Premiere Pro (via ARRI plugin), Silverstack, and ARRI's own tools

The .ari container is increasingly rare on professional sets. Most rental houses have upgraded to Alexa Mini LF or Alexa 35 fleets. However, thousands of projects shot between 2010 and 2020 exist in .ari format, and production companies archiving this footage need to understand the format's requirements.

Alexa Mini LF — .mxf

The Alexa Mini LF introduced MXF-wrapped ARRIRAW. Instead of the proprietary .ari container, the Mini LF wraps the same uncompressed ARRIRAW sensor data inside an MXF (Material eXchange Format) container — an SMPTE standard that improves interoperability with industry software.

Key characteristics of Mini LF .mxf files:

• Resolution: 4.5K Open Gate (4.5K on the LF sensor)
• Color science: ARRI LogC3 (standard on Mini LF)
• File size: Approximately 4.5–5.0 GB per minute at 4.5K Open Gate
• Container advantages: MXF is an open standard — better compatibility with post-production tools, embedded timecode tracks, and multi-channel audio support
• Audio: MXF containers can embed up to 12 channels of audio directly in the ARRIRAW file, eliminating the need for a separate audio sync step for scratch tracks

The MXF container is a significant improvement over .ari for post-production workflows because NLEs and digital asset management systems handle MXF natively more reliably than proprietary .ari files.

Alexa 35 — .mxf and .arx

The Alexa 35 is the only Alexa model that produces two ARRIRAW container formats: standard MXF-wrapped ARRIRAW and ARRI RAW Xpress (.arx).

Alexa 35 MXF-wrapped ARRIRAW is the uncompressed option:

• Resolution: 4.6K Open Gate
• Color science: ARRI LogC4 (exclusive to Alexa 35 — a wider gamut and different gamma curve than LogC3)
• File size: Approximately 5.5–6.5 GB per minute at 4.6K Open Gate
• Bit depth: 16-bit linear sensor data

ARRI RAW Xpress (.arx) is the compressed option:

• Resolution: 4.6K Open Gate
• Color science: ARRI LogC4
• File size: Approximately 2.5–3.5 GB per minute at 4.6K Open Gate — roughly 40–50% smaller than uncompressed
• Compression type: Visually lossless wavelet compression developed by ARRI
• Bit depth: 16-bit linear sensor data (same as uncompressed — compression is applied to the already-digitized sensor data)

The .arx format is strategically important for productions that want Alexa 35 image quality but need to manage storage and data transfer costs. A 40-day Alexa 35 feature shooting .arx instead of uncompressed MXF saves approximately 5–7 TB per shoot day — a total savings of 200–280 TB over the production.

How do file sizes compare across the three containers?

The storage difference between uncompressed and compressed ARRIRAW is substantial. For productions budgeting storage — whether local RAID, LTO archive, or cloud storage — the container choice has a direct financial impact.

| Container | Camera | Resolution | GB per Minute | GB per 10-Hour Day (3:1 Ratio) | TB per 30-Day Feature |

| :--- | :--- | :--- | :--- | :--- | :--- |

| .ari | Alexa SXT | 3.4K | ~2.8 GB/min | ~1.0 TB | ~30 TB |

| .mxf (uncompressed) | Alexa Mini LF | 4.5K | ~4.8 GB/min | ~1.7 TB | ~51 TB |

| .mxf (uncompressed) | Alexa 35 | 4.6K | ~6.0 GB/min | ~2.2 TB | ~66 TB |

| .arx (Xpress) | Alexa 35 | 4.6K | ~3.0 GB/min | ~1.1 TB | ~33 TB |

The practical takeaway: shooting .arx on Alexa 35 cuts storage requirements by approximately 50% compared to uncompressed MXF, with no meaningful visual difference in normal viewing conditions. The .arx file at 4.6K is approximately the same size as an .ari file from the Alexa SXT at 3.4K, but with significantly more resolution and dynamic range.

How does container choice affect card rotation?

| Container | 512 GB Card | 1 TB Card | 2 TB Card |

| :--- | :--- | :--- | :--- |

| .ari (SXT 3.4K) | ~180 min | ~360 min | ~720 min |

| .mxf (Mini LF 4.5K) | ~105 min | ~210 min | ~420 min |

| .mxf (Alexa 35 4.6K) | ~85 min | ~170 min | ~340 min |

| .arx (Alexa 35 4.6K) | ~170 min | ~340 min | ~680 min |

The Alexa 35 shooting .arx on a 1 TB card gets approximately the same record time as the original Alexa SXT shooting .ari on a 512 GB card — roughly 5.5 hours of recording before a card swap.

How does the container format affect post-production software compatibility?

Each ARRIRAW container requires specific software support for decoding, debayering, and color management. Understanding compatibility prevents the "file won't open" crisis in the edit bay.

| Container | DaVinci Resolve | Premiere Pro | Avid Media Composer | Final Cut Pro | Silverstack |

| :--- | :--- | :--- | :--- | :--- | :--- |

| .ari | Native (ARRIRAW decoder built in) | Via ARRI plugin or DaVinci Resolve link | Via ARRI plugin or AMA | Via third-party tools | Native |

| .mxf (Mini LF) | Native | Via ARRI plugin | Native via MXF | Via third-party tools | Native |

| .mxf (Alexa 35) | Native (Resolve 18.5+) | Requires updated ARRI plugin | Via MXF with correct OP-Atom support | Via third-party tools | Native |

| .arx | Native (Resolve 18.5+) | Requires ARRI plugin 2023+ | Not natively supported | Not natively supported | Native (Silverstack 6.5+) |

The Alexa 35's .arx and .mxf with LogC4 require updated software. DaVinci Resolve 18.5 and later support LogC4 natively. Premiere Pro users need the latest ARRI plugin. Avid Media Composer has limited support — most Avid workflows for Alexa 35 require transcoding to DNxHR before editing.

How does LogC4 in the Alexa 35 containers affect the color pipeline?

The Alexa 35 uses ARRI LogC4, which is a different color space than the LogC3 used by the Alexa Mini LF and Alexa SXT. LogC4 has a wider gamut and a different gamma curve. If your post pipeline was built for LogC3 — for example, LUTs designed for LogC3, or ACES IDTs configured for LogC3 — the Alexa 35 files will look incorrect until you update the color management.

The ARRIRAW container (.mxf or .arx) from Alexa 35 carries LogC4 metadata. Any software that reads the container metadata will automatically apply the correct LogC4 color transform. Software that ignores the metadata and applies a LogC3 transform by default will produce desaturated, low-contrast images.

How does Cutsio handle all three ARRIRAW containers?

Cutsio ingests .ari, .mxf, and .arx files through the enterprise raw ingestion add-on. The process is identical for all three containers: upload the native files, Cutsio generates streamable review assets with the correct LogC or LogC4 color metadata preserved, indexes every frame with Visual Intelligence, and retains the original camera files as downloadable attachments.

For mixed-fleet productions using multiple Alexa models — for example, an Alexa 35 as A-cam shooting .arx and an Alexa Mini LF as B-cam shooting .mxf — all files are ingested into the same Cutsio library and treated uniformly. The review stream is generated with the appropriate color metadata for each source format. Visual Search and Agentic Chat work across all containers simultaneously.

The original files are never modified. The .ari, .mxf, and .arx files stored in Cutsio are byte-for-byte identical to what came off the camera card.

How do you plan storage for a mixed-ARRIRAW container production?

Productions running multiple Alexa models with different containers need to calculate storage requirements for each format separately.

| Camera Mix | Container Mix | GB per Minute (Avg) | TB per 20-Day Feature |

| :--- | :--- | :--- | :--- |

| Alexa 35 (A-cam) + Mini LF (B-cam) | .arx + .mxf | ~4.5 GB/min combined | ~65 TB |

| Alexa 35 (both cameras) | .mxf (both) | ~6.0 GB/min per camera | ~86 TB |

| Alexa 35 (both cameras) | .arx (both) | ~3.0 GB/min per camera | ~43 TB |

| Alexa SXT (archive) | .ari | ~2.8 GB/min | ~40 TB |

| Alexa 35 (A-cam .arx) + Mini LF (B-cam .mxf) + SXT (C-cam .ari) | Mixed all three | ~4.5 GB/min combined | ~65 TB |

The mixed-container scenario is increasingly common as productions transition from older Alexa fleets to Alexa 35. Cutsio handles the format heterogeneity transparently — the review and search experience is identical regardless of which container the source files use.

FAQ

Can I mix .ari, .mxf, and .arx files in the same Cutsio Collection?

Yes. All three ARRIRAW containers are ingested through the same enterprise add-on and can be grouped into any Collection regardless of the source format.

Does .arx have any quality downside compared to uncompressed .mxf?

In controlled testing, ARRI RAW Xpress (.arx) is visually lossless in normal viewing conditions. The wavelet compression preserves detail well. For VFX-heavy work with extreme keying or compositing demands, uncompressed MXF may offer a marginal advantage, but for narrative and commercial production, the difference is negligible.

Does DaVinci Resolve support .arx from Alexa 35?

Yes. DaVinci Resolve 18.5 and later support .arx files natively with full LogC4 color management. No additional plugins are required.

Can I transcode .arx files to ProRes for offline editing?

Yes. The ARRIRAW Xpress files can be transcoded to ProRes in DaVinci Resolve or through ARRI's official tools. However, Cutsio eliminates the need for this transcode by generating streamable review assets directly from the .arx files.

Is ARRIRAW ingestion available for all three container types in Cutsio?

Yes. Cutsio's enterprise raw ingestion add-on accepts .ari, .mxf, and .arx containers for all supported Alexa cameras. The same Visual Intelligence indexing, streamable review asset generation, and original file attachment applies to all three container types.

For related ARRI RAW workflow guides, see the ARRICORE cloud dailies guide, the conform workflow for ARRI RAW and RED R3D, and the ARRIRAW .arx workflow guide.