Repair Corrupt MXF Files

12 July 2019 | by the restore.media team

As of yet there are no generic (automatic) video recovery tools that can repair corrupt MXF files. Unfortunately, our own tool – Restore.Media – is not an exception. However, our engineers have extensive experience in recovering both damaged and deleted MXF files manually. In this article we'll cover why manual processing is the only viable solution, as well as share our experience in repairing corrupt MXF files.

Repair Corrupt MXF Files

MXF Files Structure

Material Exchange Format (MXF) is a container or "wrapper" format used mainly for high-end production of professional video and audio media. MXF features full timecode and metadata support, and is designed to meet the SMPTE standards for professional video and audio production.

On the top level, MXF files have a complex structure of nested containers, which can be divided into Header, Body and Footer sections.

MXF Body is the key section and the biggest part of the file. It contains actual media data (video and audio streams), also called the "essence" elements.

There may be multiple different streams within one MXF file encoded in a variety of different video and audio formats. Apart from essence elements, the Body section also contains indexes and frames made of SystemMetadata.

The Header and Footer sections declare the video and audio formats/settings of the essence elements contained in the Body. This includes video resolution, frame rate, bit rate, video and audio codecs used in each media stream, etc. The Header and Footer sections also contain details about how media tracks are organized within the Body section.

Typical Incidents When MXF Files Get Corrupted

Most of the enquiries to repair corrupt MXF files can be divided into two groups:

Group 1. Damaged Header or Footer Data

If you've found one of the recorded clips unplayable, while the rest of the MXF files work fine, this may be due to the damaged metadata within the Header and Footer sections. This usually happens when the recording was interrupted by an accident and the camera failed to save the metadata in the final file. For example, you could have powered off your camera before hitting the STOP button.

If this is the case, the video and audio streams are probably fine, but the MXF container needs to be rebuilt to add the missing metadata.

How to Fix This?

In theory, if you have two video files recorded with the same camera and settings, but one of the files is unplayable, you could extract metadata from the working file and rebuild the Header and Footer of the corrupt file based on it. This is how most of the video repair tools work, including our own tool – Restore.Media.

In practice, though, this approach doesn't work with MXF files, because they don't have a consistent structure. Each MXF file has a unique Body size, length and timecode. To repair a corrupt MXF file, the Header, Body and Footer structure needs to be rebuilt from scratch.

At Restore.Media we have a solution for this – manual processing of the corrupt MXF files by our engineers. Such approach gives a 100% recovery success rate, if the media streams within the Body section are not damaged, of course.

Group 2. Deleted MXF Files or Corrupted/Formatted Memory Card

A more severe damage to MXF files may be caused if you've deleted them from a memory card, or quick-formatted the card by accident. We've also seen cases when a memory card became unrecognizable due to some glitch, and the studio had to quick-format it to be able to retrieve the files.

In this scenario, you would have to use an "undelete" tool to recover deleted MXF files. But this, again, works well only in theory. In reality, most of the "undelete" tools just can't locate all the media stream chunks due to their fragmentation. And for sure, such tools can't rebuild the MXF container properly.

How to Fix This?

The only option so far is to manually scan the memory card cluster-by-cluster to collect appropriate parts of the video and audio streams and then merge them into continuous tracks.

Here, at Restore.Media, our engineers developed a tool specifically optimized to work with fast flash memory cards, such as P2 and the HFS file system. When recovering video and audio streams, the tool allows engineers to extract raw media data while filtering out HFS clusters that contain junk data from index/metadata files.

Having recovered the raw video and audio data, it is possible to rebuild the Header and Footer and ultimately the entire structure of the MXF file.

Please note: the raw media data must remain on the memory card untouched after the deletion. It's critically important to not overwrite it with some other files. Hence, we strongly suggest to stop using the memory card and safe-eject it out of the device as soon as you realized that the files have been deleted.

The next step would be to create a RAW image (.IMG) of the memory card. It will serve you as a backup and source for recovering deleted MXF files. Having such an image file is important, because you can use it with different data recovery software or services until you get your footage recovered. Do not delete the memory card image, until you're sure the recovered files are actually playable.

We have a detailed step-by-step guide on how to act if you deleted video files from a memory card. The guide is based on SD cards, but can also be applied to other flash memory types, including Compact Flash, P2 and SxS that are often used in high-end camcorders. To read the guide, please go to this page.

Can You Repair Corrupt MXF Files for Us?

"My sincere thanks to the professionals at Restore.Media for your prompt assistance and thorough work. You had the skills to leverage a variety of approaches, landing on the one that recovered our MXF file from a corrupted SD. How you were able to do it, when a variety of software and recovery tools failed, can only be explained by the knowledge you gained in dealing with a variety of scenarios. I hope NEVER to need your services again (hope never to lose another file)... but I will be singing your praises on every platform I can and will be back with you if we need help in the future. THANK YOU - THANK YOU - THANK YOU!"

- Jeffrey Nohner

At Restore.Media we have vast experience in repairing corrupt MXF files for a number of production studios and individual videographers.

We can repair corrupt MXF files shot on virtually any camcorder, including high-end SONY PMW-F55, PWM-200, Canon EOS C300, XF305, XF300, XF105, XF100, Panasonic AG-HPX250, BlackMagic, JVC, etc. We work with footage shot in XDCAM, XAVC, DNxHD and other formats.

If you have an unfinalized/unplayable MXF file, simply upload it to a cloud storage, such as Google Drive, or any other hosting provider and then email us the link.

If you have accidentally deleted MXF files, or quick-formatted a memory card, please create a complete RAW image of the card and then share the image file with us. The image must contain data from free space clusters of the memory card. For more details on how to do this, please see this page.

In either case, our engineers will analyze the files and let you know if they can be repaired. The price depends on the file size and complexity. Once everyone agrees with the terms, our engineers will repair your corrupt MXF files and provide you with a preview along with screenshots taken across different points in the video clip, so that you can be sure the video has been actually recovered before making any payments.

If you have any further questions, please feel free to contact us.