Hard Disk File System investigation for the Magnavox 537, 535, 533, 515, 513, 2160A, 2160, 2080 &... - Page 4

I haven't had time to look at this for a while. I think my next place to try to link the directory listings you see in the Title menu to the place where the video is stored in somewhere in *.MAP files. I was going to start looking at the first 16 bytes of the records I found and compare them to each other. Most of the rest of the record looks like time indexes and doesn't point to the video directly.

I started the upload to Megaupload. I'll post the link when I get one.

I got the file uploaded now:

MultiTitlesStart.zip
242.4 MB

Same file as last time. You could try to change the extension to something the other software would like. It is just a binary file of the hard drive without anything added to it. This one is just the first 1.2 Gig of a 40 Gig hard disk.

I think moving a smaller hard drive to a larger one is possible. I know of two places where the drive size is stored so those would have to be updated and the file MPG_SEGMPG_SEGM.DAT scales with the drive size. The big question how is the data stored in the TM001_0TC001_00.MAP file. If they are relative to the beginning of the AV001_0AV001_00.MPG file then it should be very doable. If not then we would have to go through and update all the pointers to the video in the TM001_0TC001_00.MAP file. That could take some work.

There seams to be more interest in removing video files from the hard disk. I have extracted a few. They start with what I think are MPG headers. Sorry not familiar with MPG enough to say for sure. But I have extracted video and saved them as .MPG and then played them in Windows Media Player.

The TM001_0TC001_00.MAP file remains as the major road block on doing this. Also, I am still foggy on all the entries in the title list in TI000_0TI000_00.IFO. I have many of the fields figured out but there are still questions to be answered there. I do have some ideas about how it works but those have yet to be verified.

I do have postings in this thread about what I have figured out already.

I could try moving a 40 Gig to a 160 Gig to see if my resizing idea would work. That would only take a few hours.

Okay, it looks like you can resize a drive without changing the *.MAP files. I moved a 40 Gig image to a 80 Gig drive and all 7 titles worked.

Most of the changes would be done in sectors 4 and 5 in the FB000_00.LST file.

1. The drive size needs to be updated in sector 4.
2. The size of MPG_SEG_MPG_SEGM.DAT need to change from 8 to 16 sectors in FB000_00.LST. New sectors will need to be blanked out in that file after step 3 is done.
3. Then the AV001_0AV001_00.MPG file will need it's starting location moved, that is add 8 to the current number and it's length changed to the end of the disk in FB000_00.LST. Here is the hard part. You need to move all the data in this file eight sectors up since the MPG_SEG_MPG_SEGM.DAT file grew. Maybe we could move the MPG_SEG_MPG_SEGM.DAT file but that would put it at the end of the AV001_0AV001_00.MPG. That is a long ways for the heads to travel. I would not recommend that. But it could be done for testing only.

Maybe someone could come up with a LUnix script file for moving from a 160 Gig to a 500 Gig drive. You would need to know how many sectors there are on the new hard drive. Or you could lowball it and just use most of the drive and leave some small amount unused at the end.

Drive Data Structure

The sizes in this post are from moving from a 160 Gig drive to a 500 Gig drive.


I was using iBored under Windows XP to do these changes. It will let you change bytes but the file movement was more difficult. In order for me to use iBored, I would need to have enough Windows drive space to copy the smaller drive image to.

1A. To save space I would copy from sector 0 to sector 2008033 to a Windows file system, a 980 Meg file.

2A. Then with iBoard, open that image and edit the entries in sectors 4 and 5. Specifically, the entries for MPG_SEG_MPG_SEGM.DAT and AV001_0AV001_00.MPG need to be updated to what is in the 500 Gig table entry. Note that the length of AV001_0AV001_00.MPG needs to be a multiple of 16384 sectors. I believe this is the allocation unit size for the video file. Then bytes 0 through 15 will need to be updated with the drive and filesystem sizes.

3A. Copy the updated image file to the new drive.

4A. From old drive extract AV001_0AV001_00.MPG to a file with iBored. That is starting at sector 2008033 for 310476800 sectors in length. This is basically 160 Gigs so lots of Windows file system space required. Then copy that file to the new drive starting at the 8+ location, i.e. at 2008041 for the whole file.

5A. Mount 500 Gig hard drive in Magnavox.


The way I did it.

1B. Extract two files from old hard drive. One for the titles starting at sector 61231 for 1946810 sectors. Then you just use the AV001_0AV001_00.MPG file. That is starting at sector 2008033 for 310476800 sectors in length.

2B. The cheater method to update sector 4 and 5 is to let the Magnavox initialize the drive for you. Mount the new drive in the Magnavox and initialize it. Remove it to copy the old data on it.

3B. Copy title file to the new hard drive starting at position 61231 for the whole file.

4B. Copy the MPG image starting at 2008041 for the whole file to the new drive.

5B. Verify that the new for sector in the MPG_SEGMPG_SEGM.DAT are all 0s. That is sectors 2008033 through 2008040.

The drive is ready to mount in the Magnavox.



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I don't know if iBored will work under Windows Vista or 7 because writing directly to a drive requires special rights that administrators have.


Under Unix I think we might be able to use DD to do the coping. It would be nice to be able to do the copy drive to drive so you wouldn't need a temp files like I used.

On a side note. I'm going to try to get a 512 byte per sector 2 T drive running on my H2160MW9A. It might work.

I got the drive for something else so I can leave it on the DVR. In theory it should work.

I started testing the 2 T drive. I think there is a 64K limit on the used allocation unit file MPG_SEGMPG_SEGM.DAT. So the largest amount of video you can handle is 64(K of used/free bits) * 8 (M allocation units) = 549755813888 bytes.

The unit is only reporting 104 hours of HQ recording time. I guess I'll see how it does in a few days. I have it saving 24, 1 hour recordings daily. I was hoping it would say over 400 hours of HQ.

In doing this I did find that if you have the Magnavox initialize the new drive, you will get the number of sectors on the disk. It just doesn't let you use all of them. That is bytes 0 - 4 of sector 4, which is in the beginning of the FB0000_00.LST file does contain the number of sectors on the 2 T drive.

I'm looking at DFSee. I might pick up a copy to try this out. Maybe after we get the Title stuff figured out we could use it to extract video.

I just downloaded it, I'll check it out. Yep, the fee might be more than worth it.

I was looking in the TM001_0TM001_00.MAP file and I think I found the list of allocation units used. They are only 16 bit numbers. Each allocation unit is 8 Meg. Also, 0x0000 is valid but 0xFFFF is end of record marker so 0xFFFF is not usable. That means we have a maxim of 65535 * 8388608 = 549747425280 bytes in the AV001_0AV001_00.MPG file. Here is our limit that we can do. It does appear that firmware has a lower limit than this but the file system limit is about 550 Gig, about 1 Gig is for the directories and other files.

I think I can stop my experiment, it looks like it can't do it with the current file system.

I still need to figure out how to link the title with the data in the TM001_0TTM001_00.MAP file. I think we are getting close to being able to extract files. I think I can do it now but I wouldn't know the title until after I watch it.

Haven't gotten very far with these records. They are 1537 sectors long. The first part looks like they are time indexes. What I found that looks interesting is part of the record is 1507 sectors in. There is a list of the used allocation units for the recoding.

At byte 68 is a number, not sure what this is. It might be the number of bytes to use in the last allocation unit. Or maybe the number of bytes not to use in the last allocation unit. It appears to be a 32 bit number.

Next the is a series of 16 bit number that is the allocation units used. I think they are in order the recording needs to playback correctly. The few titles I have looked as so far have all be contiguous so not hard to extract.

The end of file marker is 0xFFFF.

Each allocation unit is 8 Meg or 16384 sectors. So with the starting sector for the AV001_0AV001_00.MPG file you can figure out what sectors are used in the recording.

(Allocation #) * 16384 + (Starting position for AV001_0AV001_00.MPG)

If the numbers are all contiguous like mine were then you just need to know how many sectors to copy off.

((Last Allocation #) - (First Allocation #) + 1) * 16384
I saved is as a mpg and it plays away.

Because these allocation numbers are 16 bit the file limit size for AV001_0AV001_00.MPG is 65535 * 8388608 = 549747425280 bytes. Had to -1 because 0xFFFF is end of file marker and can't be a valid allocation number.

This data can be found at sector 63132 and at increments of 1537 sectors / title. For the total of 600 title limit on the hard drive.

I looked more for a link from the title to this information and still not finding it. I'm running out of ideas for making that link.

If anyone has a Magnavox 537, 535, or 533 and has time to extract the first 100K of the hard drive and zip it and post it. I'll take a look and see if we can figure out that the limit of the new format is. My guess is the just doubled it but they might have added support the 4K sectors as well since more and more the new drives use the larger sectors. If they just scaled to 4K sectors then the drive limit might be 8X bigger. My guess is they would have kept the allocation units small so It might be a bit over 1 Gig filesystem.