BBC Radio 5 Live Data Recovery

CDR's on air credit - Elis James and John Robins

During February 2020, Cheadle DATA Recovery Ltd performed a recovery for Dave Masterman, producer for BBC Radio 5 Live Elis James and John Robins show. They had lost three podcast recordings due to data corruption on an SD memory card. This happened because the audio recorder lost power mid recording. This, and CDR's involvement afterwards, is explained on the radio show (listen below, or via YouTube). An emergency 24 to 48-hour service was provided by CDR with a successful recovery. Full technical details of the SD card failure and the associated data recovery techniques can be found at the foot of this webpage - it proved a challenging case due to interleaving audio data.

From Twitter:

This is Dave. Dave came from Manchester to London to record Elis and I doing an escape room. Dave carried all the kit. Dave has a dislocated shoulder. Dave spent two hours with us escaping from a room. This is Dave realising it hadn’t recorded. #PrayForDavepic.twitter.com/s1kNdbgCsf
John Robins (@nomadicrevery) February 5, 2020
To follow on from my former friend’s kind tweet about today’s audio disaster (@nomadicrevery), I thought I may as well now share with you the corrupt audio we have as a result. This will play in my nightmares for the next five years. pic.twitter.com/Kl9qsQWvLZ
Dave Masterman (@Masterman) February 5, 2020

Technical Details

The above tweet is about the corrupted audio which the radio producer had extracted by his own data recovery attempt. It is not a sample rate problem but instead relates as to how the specific audio recorder stores data to the SD card. The portable audio recorder in use was a Zoom H4n audio recorder. This has the capability to record up to four audio streams simultaneously. It can be used with personal radio microphones so users can move freely whilst their individual voices are recorded. In the production edit, the separate audio files are played back simultaneously so that each person has the same level of volume.

File Allocation Table (FAT) corruption after power loss

The data loss was reported due to lack of battery power and the audio recorder suddenly losing power. As a consequence of this, the File Allocation Table (FAT) had become corrupt. On inspection of the SD card, it was clear that there were no folder or file name entries associated with the required data. Full sector-by-sector scans could not locate any reference to the required files in the FAT. The FAT defines the folder and filename structure, but also (critically) defines the location of files by LBA values and deals with any splitting of files if these are not written in sequential blocks in the SD card. Without the FAT it was necessary to perform a 'RAW' recovery and to locate files by file type (e.g. .WAV, .MP3 etc).

Interleaved audio streams

The garbled high-speed audio which can be heard on the radio show is because the recovery attempt made by the show's producer failed to take into account that the three audio streams were interleaved within the raw data. Whilst their 'RAW' recovery found the start of each file it could not take into account the method in which data was written to the SD card by the Zoom H4n audio recorder. Below are examples of working audio files from the Zoom audio recorder, which show this interleave between files.

Removal of the interleave

To obtain normal audio playback it was necessary to take each of the "RAW" .WAV files in the recovery, and then write a script to separate the three streams of audio. Essentially the first 64 sectors of data were extracted to create audio 'stream 1', the following 64 sectors of data to create 'stream 2', and the third 64 sectors to create 'stream 3'. This process was repeated over and over again until each of the three audio streams were fully assembled and would playback normally.

Partial recovery of the third podcast audio file

In the radio show, you can hear how the producer tried to "Wake up" the SD card by copying some additional data to the SD card after the data loss. The golden rule of data loss/recovery applies here: if you lose data turn the device off and do not attempt to use it. The audio recordings they wished to recover had not been marked as 'allocated' within the FAT. Consequently, when new data was copied to the SD card it wrote to areas of the SD card which contained the required data. Once data has been overwritten with new data there is no method to reverse this. As a consequence, it was only possible to recover the first 15 minutes of audio associated with the third podcast recording.

Until February 2021 you can listen to the full BBC Radio 5 Live Elis James and John Robins episode from the BBC's website.

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Wayne Harrison
4 days ago
Excellent service and total transparency from beginning to end. The prices are competitive and the "no recovery, no fee" is just the icing on the cake. However, the most important thing is the quality of service and utter professionalism - no fuss, just results. I'd value absolutely no reservations about recommending Cheadle Data Recovery and, should I need such services in the future, they will be my first port of call. Delighted.
Response from the owner:Hello Wayne, thanks for the review. I am glad it was possible to achieve a positive result for your failed RAID array and your HDD. Best regards, John C. Reid.
Debbie Hilton
3 weeks ago
John was brilliant. My niece had seven years worth of lesson plans on a broken data stick and nowhere had been able to retrieve it for her until I found Cheadle Data Recovery. John was professional and transparent in regards to recovery and fees which I really appreciated. Payment only required if data is recovered. And it was! My niece was over the moon! Highly recommended this company.
Response from the owner:Hello Debbie, thank you for the review. The 32GB SanDisk memory stick had a hardware failure associated with the controller chip. Via chip off recovery it was possible to make a full recovery of the data. Best regards, John C. Reid.
James White
2 months ago
I had a new M.2 NVME drive fail on me with all my project files on so needed to do data recovery, after a bit of looking around my local area I got directed to Cheadle data recovery as the places I enquired with locally didn't deal with M.2 devices I initially called to seek quotations and John was friendly, polite and professional whilst answering any questions I had about the process, reassuring me that I was dealing with someone who knew what they were doing and giving me confidence that I wouldn't be left short as they operate on a "no recovery, no fee" basis Even going so far as to give follow up advice afterwards regarding how to create backups and other solutions to prevent this from happening in future. I really appreciate you going the extra mile and I cannot thank you enough for getting me my lost time back
Response from the owner:Hello James, thanks for the review. I am glad it was possible to make a good recovery of your failed Corsair 2TB SSD (CSSD-F2000GBMP600). The NAND had degraded and had resulted in a failure of the firmware. On receipt the SSD was stuck in a safe/engineering mode showing a capacity of 0MB. Best regards, John C. Reid.
Phill Dixon
2 months ago
Spoke to John at Cheadle Data Recovery about an enterprise grade HDD that needed recovery. He was completely upfront that the helium filled nature meant it was out of scope but hen spent a great deal of time and effort putting me in contact with places that could. He has made absolutely nothing off my call but spent 40 mins trying to help and recommending other very specialist recovery firms that could potentially help and explaining the process. Absolutely brilliant service
Response from the owner:Hello Phill, thank you for the review. Helium filled HDDs present a major technical challenge for data recovery companies when the mechanical components have failed within the HDD. I am not aware of any UK based data recovery company that has a proven success record when working on mechanical failed helium filled hard disks. As such I recommend HelpDisc/HDDSurgery in Serbia or Morde in Portugal who are making genuine recovery attempts on these disks. Both of which perform work on a 'no-recovery, no-fee' basis, and do not charge for the donor HDD. Unfortunately, I am aware of certain UK based data recovery companies which have charged £1000+ upfront for a recovery attempt on a helium filled disk, where no data has been subsequently recovered, and then on inspection of the disk it has been found that no work has actually taken place. As such, I advise those people with Helium filled HDDs to be cautious of some claims made by certain data recovery companies regarding their technical capabilities and to check the terms of work before any payment is made to the company. Whilst CDR does not work on mechanically failed helium HDDs, we do still work on helium HDDs which have suffered failure associated with the firmware, printed circuit board, bad sectors/degraded media and corruption of the filesystem. Best regards, John C. Reid.

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