_ftyp >_mdat > Test.mov = 0kbs?

Using TestDisk to undelete files
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kdscv
Posts: 8
Joined: 08 Jul 2021, 00:03

_ftyp >_mdat > Test.mov = 0kbs?

#1 Post by kdscv »

Hello,

I've used the search tool and found the excellent guide to merging videos back together. After attempting this myself and following the guide, I found the process rather easy and simple. This is amazing software.

Unfortunately, my issue now is that despite following the process my test files which are merged back together are not working.

Here are the details:

Trying to recover two videos shot on a Nikon Z6 camera on a brand new first time used Sony G XQD 32GB.

I'm able to recover the two videos following the process as described here: https://www.cgsecurity.org/testdisk.pdf

However, when merging the files using the command _ftyp >_mdat > Test.mov the new files are 0bytes and have no metadata. I've tried variations of which file to merge with others through several tests but the result are the same.

Either I'm doing something incorrect or perhaps the data is lost? I'm still trying to figure all this out but much appreciation to anyone who can point me in the right direction.

In the meantime, I'll continue my tests.
Thanks in advance.
-kdscv

kdscv
Posts: 8
Joined: 08 Jul 2021, 00:03

Re: _ftyp >_mdat > Test.mov = 0kbs?

#2 Post by kdscv »

Looking at the files I'm assuming the larger _ftyp.mov would correspond to the largest _mdat file?

These are my files (I'll use example filenames):

f081734_mdat.mov 3,923,667kb
f193870_mdat.mov 3,678,987kb
f358473_ftyp.mov 2,3345kb
f123144_ftyp.mov 2,2873kb

Since they are video, I can see the footage length info on the ftyp files. Which are each 5min or so one being slightly smaller than the other. All the data seems to be there.

But this is where I don't understand. How do I determine which goes with which? I've been using this logic largest _mdat corresponds with the _ftyp that has the greater footage length.

I'm also wondering whether are any other ways to put these files back together apart from the _ftyp >_mdat > Test.mov command?

recuperation
Posts: 1661
Joined: 04 Jan 2019, 09:48
Location: Hannover, Deutschland (Germany, Allemagne)

Re: _ftyp >_mdat > Test.mov = 0kbs?

#3 Post by recuperation »

I'm sorry - I am not familiar with the internals of that format!

kdscv
Posts: 8
Joined: 08 Jul 2021, 00:03

Re: _ftyp >_mdat > Test.mov = 0kbs?

#4 Post by kdscv »

recuperation wrote: 09 Jul 2021, 08:47 I'm sorry - I am not familiar with the internals of that format!
Hello thanks for taking the time to read over my post.

What do you mean by that? What format are you not familiar with?

This is simply an MOV recorded clip that was recovered into two pieces. _ftyp and _mdat

After entering the command line function _ftyp >_mdat > Test.mov executes and opens VLC, nothing plays and the file it creates is always 0kb in size.

Judging by the sizes of the _mdat parts and the meta data from the _ftyp parts, the data does seem to be intact and recovered, just in two pieces.

kdscv
Posts: 8
Joined: 08 Jul 2021, 00:03

Re: _ftyp >_mdat > Test.mov = 0kbs?

#5 Post by kdscv »

After doing more searching I found this thread:

viewtopic.php?t=6442

In in it I found this post.
Re: Recovered Video Freezes on First Frame & Screen goes dark

#5 Post by oj123456 » 20 Aug 2016, 14:00
SOLVED!

If anyone else is having this issue, which is basically that the files were not playable but you have data there, then the next step after combining them as kindly written above with cat file1ptype.mov file2mdata.mov > 123.mov is that you need to get GS - the application is free to download and try, then all you have to do is use a reference file recorded with the same setup (camera/lens etc) and that program will piece it together for you!

THANK YOU SO MUCH

I downloaded GS from here http://www.grauonline.de - i was so happy i actually paid for the license, but there are a bunch of links online telling you how to double the filesize and trick it if you need it for free. Guess on this one the germans actually came through!!!
Top
Has anyone else tried this to see if this software works?

recuperation
Posts: 1661
Joined: 04 Jan 2019, 09:48
Location: Hannover, Deutschland (Germany, Allemagne)

Re: _ftyp >_mdat > Test.mov = 0kbs?

#6 Post by recuperation »

kdscv wrote: 09 Jul 2021, 14:24
recuperation wrote: 09 Jul 2021, 08:47 I'm sorry - I am not familiar with the internals of that format!
This is simply an MOV recorded clip that was recovered into two pieces. _ftyp and _mdat

After entering the command line function _ftyp >_mdat > Test.mov executes and opens VLC, nothing plays and the file it creates is always 0kb in size.
_ftyp and _mdat are internal parts of a MP4/MOV container. Just sticking one after another does not generate a video clip that complies with the container specification.

But as I said, I am not familiar with the internals of that format, I may be totally wrong, because my statements contradicts the one made by Christophe Grenier here:

viewtopic.php?p=21011#p21011

kdscv
Posts: 8
Joined: 08 Jul 2021, 00:03

Re: _ftyp >_mdat > Test.mov = 0kbs?

#7 Post by kdscv »

Hello there!
I am not familiar with the internals of that format
May I ask simply because I'm not sure I'm understanding. What exactly do you mean about being familiar with these internals? The internals of MOV/MP4 files? Oppose to what exactly?

I'm still toiling away at this but it's been an interesting deep dive into data recovery which has been fascinating, I'm interested in learning as much as I can.

Thanks very much for replying.

recuperation
Posts: 1661
Joined: 04 Jan 2019, 09:48
Location: Hannover, Deutschland (Germany, Allemagne)

Re: _ftyp >_mdat > Test.mov = 0kbs?

#8 Post by recuperation »

kdscv wrote: 20 Jul 2021, 01:43 Hello there!
I am not familiar with the internals of that format
May I ask simply because I'm not sure I'm understanding. What exactly do you mean about being familiar with these internals? The internals of MOV/MP4 files? Oppose to what exactly?
The internal structure of a MOV/MP4 file.

kdscv
Posts: 8
Joined: 08 Jul 2021, 00:03

Re: _ftyp >_mdat > Test.mov = 0kbs?

#9 Post by kdscv »

Would you know where can I learn more about their internal structures? Seems like I have all the parts, now I'm learning how to piece them back together.
Last edited by kdscv on 21 Jul 2021, 20:11, edited 2 times in total.

recuperation
Posts: 1661
Joined: 04 Jan 2019, 09:48
Location: Hannover, Deutschland (Germany, Allemagne)

Re: _ftyp >_mdat > Test.mov = 0kbs?

#10 Post by recuperation »

You would just fill a search engine as I would do with keywords like "mp4 file format".

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