All times are UTC - 5 hours [ DST ]




Post new topic Reply to topic  [ 29 posts ]  Go to page Previous  1, 2
Author Message
 Post subject: Re: Data Recovery Digitech Jamman Stereo (guitar pedal)
PostPosted: August 9th, 2019, 20:00 
Offline
User avatar

Joined: September 8th, 2009, 18:21
Posts: 11887
Location: Australia
Could we see an example of a header and footer from phrase.wav ?

BTW, here is your broken URL:

http://www.at91.com/viewtopic.php?f=9&t=29088

_________________
A backup a day keeps DR away.


Top
 Profile  
 
 Post subject: Re: Data Recovery Digitech Jamman Stereo (guitar pedal)
PostPosted: August 9th, 2019, 22:55 
Offline
User avatar

Joined: September 8th, 2009, 18:21
Posts: 11887
Location: Australia
framp wrote:
Just an update for everybody facing a similar issue: I managed to login into the looper via UART. The looper is runnign QNX, a posix compliant Unix. I was able to dump the NAND data and a tool called etfsctl.

How did you dump the NAND?

Did you dd the NAND "drive" to an SD card?

Did you copy (cat) individual files to your SD card?

You say you scanned your dump for RIFF headers. Do the unplayable WAVs correspond to deleted loop data that were discovered by the scan?

_________________
A backup a day keeps DR away.


Top
 Profile  
 
 Post subject: Re: Data Recovery Digitech Jamman Stereo (guitar pedal)
PostPosted: August 9th, 2019, 23:22 
Offline
User avatar

Joined: December 4th, 2012, 1:35
Posts: 3420
Location: Adelaide, Australia
duplicate post


Last edited by HaQue on August 9th, 2019, 23:25, edited 1 time in total.

Top
 Profile  
 
 Post subject: Re: Data Recovery Digitech Jamman Stereo (guitar pedal)
PostPosted: August 9th, 2019, 23:24 
Offline
User avatar

Joined: December 4th, 2012, 1:35
Posts: 3420
Location: Adelaide, Australia
I haven't been following the thread, but saw recent posts about first dumping a NAND, then issues playing files.

I think Franc may be alluding to this, but there is a few possible reasons:

1) the format could be different than straight .wav
2) post processing done by decoder to not use all of the .wav spec or in a different manner than intended
3) your dump included information such as SA bytes or ECC or something that further needs to be stripped out
4) files are not stored in a totally concurrent fashion... I have seen recently while hacking some games consoles that ROM files for example have a block of DATA and if the ROM is bigger than this, the next block is stored somewhere else, not straight after.
5) your dump might be ok, but not ECC corrected, so bit errors are present. (Linux systems that use NAND should have this built in though at a driver level)
6) may be some binary to ascii conversion happening, but I would think files would be totally screwed up if this were the case (thinking like specifying BINARY option in some rudimentary older protocals)

kudos or getting this far. I remember when I first got a prompt from a Microvax 3400 after a friend came across 2 complete but disassembled systems. right at the start of accessable internet, searching was in infancy, and I had help from a Tafe college lecturer that correctly identified the plug that looked like a LAN port as a terminal adapter port. not knowing anything about unix, terminals etc. this opened up a whole new world


Top
 Profile  
 
 Post subject: Re: Data Recovery Digitech Jamman Stereo (guitar pedal)
PostPosted: October 5th, 2019, 7:06 
Offline
User avatar

Joined: May 2nd, 2019, 3:08
Posts: 9
Location: Next to Stuttgart, Germany
Just a final update: I finally managed to extract the NAND data from the looper and also spent a lot of time to understand the dump format (QNX etfs filesystem) and to extract the files from the raw dump. Unfortunately the transactions in the dump which contained the data of the deleted loops was cleared with 0xff :evil: I frankly have no idea why this happened. Looks like the data was cleared in parallel when the transaction metadata was cleared.

As I said I spent a lot of time understanding the etfs format and design. The code I created to recover all files which had transactions in the raw etfs dump is available here in github. It's not very elegant code because I had a lot of trial and error coding loops but finally it recovers the files. Maybe it's useful for somebody in the future who has to recover data from an etfs filesystem.


Top
 Profile  
 
 Post subject: Re: Data Recovery Digitech Jamman Stereo (guitar pedal)
PostPosted: October 6th, 2019, 17:39 
Offline
User avatar

Joined: September 8th, 2009, 18:21
Posts: 11887
Location: Australia
framp wrote:
As I said I spent a lot of time understanding the etfs format and design. The code I created to recover all files which had transactions in the raw etfs dump is available here in github. It's not very elegant code because I had a lot of trial and error coding loops but finally it recovers the files. Maybe it's useful for somebody in the future who has to recover data from an etfs filesystem.

Many thanks!

_________________
A backup a day keeps DR away.


Top
 Profile  
 
 Post subject: Re: Data Recovery Digitech Jamman Stereo (guitar pedal)
PostPosted: October 10th, 2019, 13:57 
Offline
User avatar

Joined: May 2nd, 2019, 3:08
Posts: 9
Location: Next to Stuttgart, Germany
I just detected your update. I unfortunately missed to enable thread update notification with eMail :?
fzabkar wrote:
How did you dump the NAND?

Code:
etfsctl -d /dev/etfs2 -R /mnt/sdfs/etfs2.img

See http://www.qnx.com/developers/docs/6.5. ... fsctl.html
Quote:
Did you dd the NAND "drive" to an SD card?

Hm ... no, I used the oficial QNX command. Do you think it's worth to give it a try to get more data?
Quote:
Did you copy (cat) individual files to your SD card?

Yes, but that way I only got the existing files, not the deleted files.
Quote:
You say you scanned your dump for RIFF headers. Do the unplayable WAVs correspond to deleted loop data that were discovered by the scan?

This scan was useless because the way etfs works. Whenever you update a data block with a RIFF header for a WAV file a new data block is written with the updated data including the RIFF header and the old data block is unlinked from the file. So every update of a wav header data block creates a new scan match as long as the deleted data block is not cleared or reused by another file.


Top
 Profile  
 
 Post subject: Re: Data Recovery Digitech Jamman Stereo (guitar pedal)
PostPosted: October 10th, 2019, 14:07 
Offline
User avatar

Joined: May 2nd, 2019, 3:08
Posts: 9
Location: Next to Stuttgart, Germany
Same for you - missed you comment - sorry.
HaQue wrote:
1) the format could be different than straight .wav
2) post processing done by decoder to not use all of the .wav spec or in a different manner than intended

I was able to reciver the not deleted fie from the NAND dump. There was some special handling required to extract the file but the format was correct.
Quote:
3) your dump included information such as SA bytes or ECC or something that further needs to be stripped out

That's done by etfsctl to get a device independent representation of the etfs content.
Quote:
4) files are not stored in a totally concurrent fashion... I have seen recently while hacking some games consoles that ROM files for example have a block of DATA and if the ROM is bigger than this, the next block is stored somewhere else, not straight after.

I assume all the data is stored in the NAND.
Quote:
5) your dump might be ok, but not ECC corrected, so bit errors are present. (Linux systems that use NAND should have this built in though at a driver level)

Extraction of non deleted files was possible and I detected no ECC errors
Quote:
6) may be some binary to ascii conversion happening, but I would think files would be totally screwed up if this were the case (thinking like specifying BINARY option in some rudimentary older protocals)

I had to use little endian format and everything was OK.

Quote:
kudos or getting this far. I remember when I first got a prompt from a Microvax 3400 after a friend came across 2 complete but disassembled systems. right at the start of accessable internet, searching was in infancy, and I had help from a Tafe college lecturer that correctly identified the plug that looked like a LAN port as a terminal adapter port. not knowing anything about unix, terminals etc. this opened up a whole new world

Yes, I was glad when I managed to enter the Unix system via console and to find some doc and C code in the net about etfs and etfsctl.


Top
 Profile  
 
 Post subject: Re: Data Recovery Digitech Jamman Stereo (guitar pedal)
PostPosted: October 11th, 2019, 3:35 
Offline
User avatar

Joined: May 2nd, 2019, 3:08
Posts: 9
Location: Next to Stuttgart, Germany
@fzabkar I tried dd and got an empty output file. Actually I remembered I already tried this when I got access to the system. That's the tool to clone a hard disk for data recovery actions. But looks like the etfs doesn't comply with the Linux device protocol and returns end of device immediately. I tried to find the source code for etfsctl to get an idea how the data can be extracted from NAND but failed :(

Comment for mods/admins: How many comments do I have to write until my posts will not require an approval from you any more? It's really annoying :?


Top
 Profile  
 
Display posts from previous:  Sort by  
Post new topic Reply to topic  [ 29 posts ]  Go to page Previous  1, 2

All times are UTC - 5 hours [ DST ]


Who is online

Users browsing this forum: No registered users and 7 guests


You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot post attachments in this forum

Search for:
Jump to:  
Powered by phpBB © 2000, 2002, 2005, 2007 phpBB Group