Occasionally corrupted rips

The place to discuss Mac OS X version of MakeMKV
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Jabes
Posts: 17
Joined: Mon May 21, 2012 7:09 pm

Occasionally corrupted rips

Post by Jabes »

I use my old macbook air for ripping dvds and blu rays. Occasionally, just occasionally, the rip doesn't play properly. If I restart makemkv and re-rip it rips it again and it does work fine.

Seems like an unusual problem - has anyone seen anything like this?
Woodstock
Posts: 10381
Joined: Sun Jul 24, 2011 11:21 pm

Re: Occasionally corrupted rips

Post by Woodstock »

Debugging logs from the bad rips would be very helpful. See the FAQ in my signature for how to do that, if you don't have it turned on all the time (I do... simpler if I discover a problem).

Playback can have its own problems, regardless of the rip. It helps to have multiple players available to see if the problem is the player, or the file. A bad file should have problems in the same place, whatever is playing it.

Even where you store it can cause issues - if you use a network share, and the network has too much traffic on it momentarily, you get what looks like a bad rip during playback. This is especially likely on a Bluray rip, simply because the bit rate is so high for playback.
Jabes
Posts: 17
Joined: Mon May 21, 2012 7:09 pm

Re: Occasionally corrupted rips

Post by Jabes »

I will turn debug logs on.

It's not playback that is an issue, I see it in VLC, and also in XBMC - and when I re-rip the same film everything is fine. I have done binary compares of the rips and seen considerable differences. Usually the problem presents on playback within the first minute or so.

Here are things I have tried:
1. I bought a new blu ray player, different brand
2. I have run full mac diagnostics as was concerned about memory problems
3. I have run a fairly intensive set of file copies across my lan to check my NAS and compared them

I use my macbook for ripping and not much else and thought the issue was when the machine had suspended and resumed still in makemkv, so I started restarting it and had better results. But I have since seen this even when trying it.

I will report back with debug logs next time
Woodstock
Posts: 10381
Joined: Sun Jul 24, 2011 11:21 pm

Re: Occasionally corrupted rips

Post by Woodstock »

Saving to a LAN introduces its own variables to the equation. Normally, MakeMKV can identify delays in the writing to the destination, but it cannot identify corrupted writes. You might want to check the SMART data for your server's disks... It is possible that you have a bad spot.

I have a server where several disks are failing (it's used for experimentation), and you only see the corruption when you READ the data back. The operating system doesn't to a verify-after-write, and the disk isn't reporting them as failures, so....
Jabes
Posts: 17
Joined: Mon May 21, 2012 7:09 pm

Re: Occasionally corrupted rips

Post by Jabes »

The destination is a synology NAS, I do nightly smart checks and monthly full checks.
I didn't see corruption with a big read / copy / compare test from the same machine when I first had this problem, but I will repeat this.

It seems odd that when I restart the machine and do the rip again it is absolutely perfect, and this hasn't happened until recently. I can't connect it with a specific new version of makemkv though because it is a 1 in 10 problem and I'm not buying disks as fast as when I did my original backlog of rips.
Jabes
Posts: 17
Joined: Mon May 21, 2012 7:09 pm

Re: Occasionally corrupted rips

Post by Jabes »

From the mac which I run makemkv on I have now run 90 gb of file copies across the lan to the same destination as makemkv and compared the results, again across the lan. Not a problem whatsoever.

Best wishes
James
Jabes
Posts: 17
Joined: Mon May 21, 2012 7:09 pm

Re: Occasionally corrupted rips

Post by Jabes »

This has just happened to me again. Debug log would be attached but the board attachment has been reached, so here is a link to an upload to pastebin - http://pastebin.com/6MhRPHJ3
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