Corrupt MPEG after a crash during capture

[Karovaldas]

I have a problem with a MPEG2 file I captured using AverMedia 550 TV tuner. I can view 2.5 hours of the recording and then the video just stops. VirtualDubMod informs me that I have a "block error".

Here's what I did: I programmed UltraTV program to capture 3 hours of cable broadcast using the built-in hardware MPEG2 encoder. Came home after work and the recorder was still going despite the fact that it was already well into 5th hour. It did not stop after three hours like it was supposed to. The computer also displayed Windows XP error report telling me that UltraTV program has crashed. What I have on the hard-drive is a 16GB+ file. This is a pre-existing condition where files that I record with this setup frequently cause Windows Explorer to crash when I am opening them for viewing or deleting. The Explorer resets itself so I haven't had the time to look into this more carefully.

I used MPEG2SPLIT2 to try to chop up the file and extract what I need from the program. The first two one-hour segments came out fine. The third one stops on the 24th mintute. I cannot navigte past a certain frame and cannot see or hear anything after that.

First, how do I diagnose the problem?

Second, how do I fix it (provided it can be fixed)?

Here's what I tried:
- Demuxing with TMPEGEnc--stops at the frame in question and produces a valid video stream up to that point as far as I can tell. "Merge&Cut" freezes.
- bbMPEG would not even allow the file to be inserted in the appropriate field
- I tried to import this file into VirtualDubMod and again--stops at the fram in question.
- I tried to process the program file in PVStrumento and that program also crashed at the same point.
- I also used DVD2AVI and tried to create a project for the segment inquestion: everything works fine until I get to the part where corruption is present and once I navigate past that point, the file freezes.
- Adobe's Premiere Pro and Encore DVD 1.5 both freeze with this file.
- AVSEdit script using DirectShowSource() does not open the file either. This seems to be a strange behavior, because files produced with this encoding method open with DirectShowSource() but not with MPEG2Source().

Any helpful hints?! I have a ton of codecs in my computer and I wish I knew how to control them better. Please let me know where I can start looking.

Thanks a bunch!

[setarip_old]

Demuxing with TMPEGEnc--stops at the frame in question and produces a valid video stream as far as I can tell.

Also in TMPGEnc, try the following:

TMPGEnc>>File>>MPEGTools>>Merge&Cut

Try to move the slider to just past the "problem" point and save the remainder...

[Karovaldas]

Also in TMPGEnc, try the following:

TMPGEnc>>File>>MPEGTools>>Merge&Cut

Try to move the slider to just past the "problem" point and save the remainder...

Unfortunately, in "Merge & Cut": after clicking "Edit" the program just freezes.

[setarip_old]

Although it shouldn't make any difference (stranger things have been known to happen ;>}), after you've loaded the file into the "Merge&Cut" window, try doubleclicking on the filename instead of clicking on the "Edit" radiobutton...

[Centurione]

Have you tried demuxing with PVAStrumento or ProjectX.
They both try to correct errors in MPEG stream that can easily occur in DVB broadcast.

regards, Centurione

[CirTap]

Hi,
"First" - have you verified your harddrive?
The symptoms sound very familiar to me, as I had several bad sectors on my "video drive" causing every single app accessing the file to crash; some even caused the whole harddrive (separate disc) to disappear from device manager and I had to reboot.

"Second": IF there's a physical damage to the disc you're out of luck with any of the "regular" video tools that usualy read, parse, examine the file for whatever purpose (indexing etc.) So any of them will either freeze or crash.
I don't recall if any of the tools allows direct "sector" access of a MPEG file (no editor certainly will), but you may try Jsoto's "Cutfile"
http://www.videohelp.com/~jsoto/others.htm
and "sneak" your way to the bad sector address/byte offset using a multiple of 4096 bytes (NTFS default sector size). Maybe one of the apps can tell you the byte position of the frame in question; add 4098 and cut from there with Cutfile.
if Cutfile crashes then advance by another 4096 bytes until it can read the file, and cut out whatever you can get. Try small steps, as it's likely that around the first "bad sector" you may run into a few more. It's tedious, but maybe the only chance to get the most from the damaged file/harddrive.

Still presuming the drive is physically corrupted, you may have to try some file recovery tools to extract the remaining good sectors "around" onto another partition or disc.

This would get you at least a file (or several fragments) that can be opened by any of the video apps you mentioned, even though the video data from the damaged sectors is likely to be lost in nirvana. However, a few thousand bytes of lost MPEG data will only cause a little hick-up in the final video: better than nothing.

Good luck.
CirTap