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'[TECH] Truncated file recovery'
2010\05\09@071235 by Electron

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Hi,
I have a portable MPEG2 video recorder which records on FAT32 formatted CF32 cards.
While I was out with my bike I recorded everything, as usual. Unfortunately a short
power interruption has caused one file not to be closed, and now it appears as being
0 bytes long. However, a lot of data was recorded there, and is incidentally the
data I was most interested in.

I have tried with File Scavenger, with Easy Recovery, I have Googled for other utils
but found nothing that seems that may help.

Is there any utility or way to get the data back from that truncated file? I was
thinking to open the file and set its length to an arbitrary high value.. but would
that work?

Of course I am currently avoiding any operation (such as CHKDSK /f ) that would modify
the original device.

Thanks.

Mario

2010\05\09@084608 by Yigit Turgut

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{Quote hidden}

It depends on your recorder device. If you take a closer look at the whole
recording operation, device reads from camera and saves the data to
specified location. In your case your location is a CF card and when the
power is interrupted device stopped reading from camera thus couldn't
complete the last headers and structure of th file etc. You need to get
inner details of your recorder because afaik there is no general approach to
this situation. Device may use some portions of internal memory as a buffer
or it may directly write to CF card. Usually low resolution data is written
directly to external storage but when the quality increases then write speed
to card might not catch up with the data coming from the camera sensor
itself, like HD.

Another approach would be to get an binary image of your card so that you
can play with it without corrupting the original data. If you are lucky your
device directly writes to CF card (without a buffer) and maybe you can
extract some data from there.You will need to create an identical custom
video file which will have valid headers and structure also same in data
size.After that you can try to swap the data parts of your stuff and the
custom created one.

If you can provide additional information about your recorder I am sure
people here will try to figure something out.

2010\05\09@085723 by Marcel Birthelmer

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First off, I suggest using WinHex to generate an image of the device
in question. WinHex also has some FAT32 diagnostic features that can
help you.
Basically, you have to (either programatically or manually) trace the
cluster chain of your file until you get to a point where the next
cluster in the chain is either invalid or not removed from the list of
free clusters, indicating that the FAT management software stopped
working. All the data up to that point should be fine. Then you can
manually update the FAT entry for the file, or more simply, just
extract all the data in the cluster chain into a file.
- Marcel

On Sun, May 9, 2010 at 1:12 PM, Electron <spam_OUTelectron2k4TakeThisOuTspaminfinito.it> wrote:
{Quote hidden}

> -

2010\05\10@175249 by Vitaliy

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Electron wrote:
> I have a portable MPEG2 video recorder which records on FAT32 formatted
> CF32 cards.
> While I was out with my bike I recorded everything, as usual.

I would love to see a picture of your setup. Especially the mounting
hardware.

Vitaliy

2010\05\11@020956 by Tamas Rudnai

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I do not understand btw why do they use FAT filesystem nowadays. You have to
pay to Microsoft, plus the filesystem itself is rubbish based on 20 year old
technology with no recovery option. People should start using a modern
journaling filesystem for these large flash disks. I know, FAT is better
suit to small micros as there is no need to calculate too much, however, if
a mibile phone can play 3D games and if a digital camcorder can include
useless picture effects then they could implement a proper filesystem driver
too.

Tamas


On Mon, May 10, 2010 at 10:51 PM, Vitaliy <.....piclistKILLspamspam@spam@maksimov.org> wrote:

> Electron wrote:
> > I have a portable MPEG2 video recorder which records on FAT32 formatted
> > CF32 cards.
> > While I was out with my bike I recorded everything, as usual.
>
> I would love to see a picture of your setup. Especially the mounting
> hardware.
>
> Vitaliy
>
> -

2010\05\11@043200 by Alan B Pearce

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> I do not understand btw why do they use FAT filesystem nowadays. You have
> to
> pay to Microsoft,

No, you only pay Microsoft if you use long filenames. The FAT file system
itself is not owned by Microsoft.

2010\05\11@103533 by Herbert Graf

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On Tue, 2010-05-11 at 07:09 +0100, Tamas Rudnai wrote:
> I do not understand btw why do they use FAT filesystem nowadays. You have to
> pay to Microsoft, plus the filesystem itself is rubbish based on 20 year old
> technology with no recovery option. People should start using a modern
> journaling filesystem for these large flash disks.

Name one? What journaling filesystem would you use that gives the
benefits of FAT32, without paying Mickeysoft?

Remember, most people use windows, so any file system you use MUST be
supported natively by windows (no installing stuff to get it working).
That rules out pretty much all file systems other then FAT/exFAT and
NTFS.

Guess who you have to pay to use NTFS?

The fact is there is NO other viable option then FAT. As horrible as you
think it is, it's what we've got.

Frankly, FAT works very well for flash cards. The only real limitation
that is routinely hit these days is the max file size, hence the
creation of exFAT.

TTYL



2010\05\11@120212 by Gerhard Fiedler

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Herbert Graf wrote:

> On Tue, 2010-05-11 at 07:09 +0100, Tamas Rudnai wrote:
>> I do not understand btw why do they use FAT filesystem nowadays. You
>> have to pay to Microsoft, plus the filesystem itself is rubbish
>> based on 20 year old technology with no recovery option. People
>> should start using a modern journaling filesystem for these large
>> flash disks.
>
> Name one? What journaling filesystem would you use that gives the
> benefits of FAT32, without paying Mickeysoft?
>
> [...]
>
> Frankly, FAT works very well for flash cards.

It's been a long time, but IIRC there were quite a number of tools
around to do semi-automated recovery on FAT/FAT32 disks back in the
days. They should still be out there.

Gerhard

2010\05\11@121057 by Tamas Rudnai

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On Tue, May 11, 2010 at 9:32 AM, Alan B Pearce <Alan.B.PearcespamKILLspamstfc.ac.uk>wrote:

> No, you only pay Microsoft if you use long filenames. The FAT file system
> itself is not owned by Microsoft.
>

I guess that's the VFAT system, and FAT12 or FAT16 which is not owned by MS?
What about FAT32?

Tamas



>
> -

2010\05\11@121818 by Tamas Rudnai

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On Tue, May 11, 2010 at 3:35 PM, Herbert Graf <.....hkgrafKILLspamspam.....gmail.com> wrote:

> Remember, most people use windows, so any file system you use MUST be
> supported natively by windows (no installing stuff to get it working).
> That rules out pretty much all file systems other then FAT/exFAT and
> NTFS.
>

No, you can write drivers... So you do not need to be supported by drivers
on your Windows installation disks as it can be installed any time.

Also there are other options, like providing Samba instead of raw FS
access...

In my opinion it is just a laziness from the camcorder manufacturers not to
thinking about alternatives.

2010\05\11@122818 by Tamas Rudnai

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On Tue, May 11, 2010 at 5:02 PM, Gerhard Fiedler <EraseMElistsspam_OUTspamTakeThisOuTconnectionbrazil.com
> wrote:

> It's been a long time, but IIRC there were quite a number of tools
> around to do semi-automated recovery on FAT/FAT32 disks back in the
> days. They should still be out there.
>

Back in DOS times I was doing hard drive recovery service. Manual or
automatic tools, does not matter as most of the times the client already
tried to recover the files by themselves knowing nothing about it. And it
includes even formatting the disk! I mean, how could you recover files after
that? Maybe with a military grade analyser that works on the slack magnetic
fields or something :-)

Anyway, I think a filesystem should be fault tolerant -- forgetting
unmounting the disk before removing it, or power fail or ESD or even
Software bug should not cause loss of everything or huge bunch of files.
maybe portion of your data would be lost -- uncommitted data -- but the old
version of the file should be still there anyway. Theoretically you have two
copy of the FAT in FAT FS which is exactly for this reason, but that does
not really help in practise. At least that is my experience.

Tamas



>
> Gerhard
> -

2010\05\11@155717 by Herbert Graf

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On Tue, 2010-05-11 at 17:18 +0100, Tamas Rudnai wrote:
> On Tue, May 11, 2010 at 3:35 PM, Herbert Graf <hkgrafspamspam_OUTgmail.com> wrote:
>
> > Remember, most people use windows, so any file system you use MUST be
> > supported natively by windows (no installing stuff to get it working).
> > That rules out pretty much all file systems other then FAT/exFAT and
> > NTFS.
> >
>
> No, you can write drivers... So you do not need to be supported by drivers
> on your Windows installation disks as it can be installed any time.

Right, so for it to be MASSIVELY adopted you plan to write a driver for
every OS out there and maintain it? I wish you luck.

The fact is manufacturers are going to go with the easiest route. The
easiest route at minimum is to choose a file system that is supported by
the vast majority of machines out there. The vast majority of machines
support FAT and NTFS, there is no disputing that.

> Also there are other options, like providing Samba instead of raw FS
> access...

Wah?? That's even worse sounding. When I plug a device in my machine I
WANT it to show up as a regular drive. Most manufacturers tend to agree
with this position (Apple being the biggest outlier, and they get
hammered for it alot).

What are you envisioning anyways? I plug a flash card into a machine and
it shows up as a network share or something? How does that benefit
ANYONE?

> In my opinion it is just a laziness from the camcorder manufacturers not to
> thinking about alternatives.

It doesn't matter if you label it lazy or not, the manufacturers are
interested in making their products as easy to use for as little money
as possible, that's the nature of the game. Farting around for no
financial benefit is NOT what a company interested in making money is
likely to do.

TTYL


2010\05\11@162825 by Michael Watterson

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Herbert Graf wrote:
{Quote hidden}

agreed 100%

2010\05\13@063407 by Electron

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Thank You for all Your replies. I'm glad that my post has generated also some very
interesting discussions on filesystems.

I have bad news. I don't think that the file (being a proprietary format) is recoverable.
As I didn't find any utility able to recover the truncated file, I tried to se the length
of it manually, via some KERNEL32.DLL calls. Unfortunately, although it "formally" works
like a charme, everything is zero'ed.

In the end it will be easier for me to return there in that enduro track "paradise" and
film it again.

Vitaliy: unfortunately right now I have no working photocamera. Anyhow, this is what I use:
http://www.dogcamsport.co.uk/hqr1-with-sony-hq1-bullet-camera-kit.htm

The way I've fixed the camera is under the helmet's visor, to protect it. I have used
normal (nylon?) ties. I'm using a RJ45 connector behind the helmet and normal Ethernet
(shielded) cables till another RJ45 connector on the recorder side, which I keep on my
pouch.

It's a MPEG2 recorder and this is the best thing of it, for the rest it's quite troublesome
as it heats way too much (and after about 1 hour it turns off by itself because of that),
battery lasts about 80 minutes, but I am using a BatteryGeek auxiliary battery to fix the
problem. It can record even on 32GB CF cards, so it's good for long rallies or whole enduro
races.

Cheers,
Mario

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