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#273083 - 30/12/2005 12:37 Cyclic Redundancy Check?
CrackersMcCheese pooh-bah Registered: 14/01/2002 Posts: 2489	I get this error when trying to copy a 2.5gb mpg file from one hard drive (d) to another (c). Whats it mean? Googling just says its a dirty CD but obviously it can't be. Both drives are working fine and I copied 3 other similarly-sized files (that I put on drive D at the same time) with no problems. The file in question plays fine on drive d. Any ideas?
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#273084 - 30/12/2005 13:40 Re: Cyclic Redundancy Check? [Re: CrackersMcCheese]
tfabris carpal tunnel Registered: 20/12/1999 Posts: 31597 Loc: Seattle, WA	Cyclical Redundancy Check, or CRC, is an algorithm for making sure that data gets transferred correctly from one device to another. Whether over a network, or between types of media, or even in RAM. The error means (in theory), you've got a bad section of hard disk somewhere. The fact that the MPG file plays fine isn't important because streaming audio and video formats are supposed to tolerate data errors. It could just be one byte of data that's wrong, and you wouldn't see or hear that on playback. _________________________ Tony Fabris
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#273085 - 30/12/2005 15:11 Re: Cyclic Redundancy Check? [Re: CrackersMcCheese]
mlord carpal tunnel Registered: 29/08/2000 Posts: 14494 Loc: Canada	What operating system, and where exactly does the message appear (GUI, logs, ??)? The CRC message I added to Linux years ago, simply indicates a spurious error on the cable between a hard disk and the computer -- the operation is then retried and no data is lost or corrupted in that specific case. Cheers
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#273086 - 30/12/2005 22:25 Re: Cyclic Redundancy Check? [Re: tfabris]
Roger carpal tunnel Registered: 18/01/2000 Posts: 5683 Loc: London, UK	Quote: It could just be one byte of data that's wrong, and you wouldn't see or hear that on playback. Yeah, so just use something that will ignore the error when copying the file. I assume that since you mention drive C and drive D that you're talking about Windows. Try using copy, or xcopy, or robocopy, rather than Windows Explorer. _________________________ -- roger
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#273087 - 31/12/2005 01:16 Re: Cyclic Redundancy Check? [Re: CrackersMcCheese]
gbeer carpal tunnel Registered: 17/12/2000 Posts: 2665 Loc: Manteca, California	Really! A 2.5 GigaByte file? Dosen't that bust some kind of Windows file size limit? _________________________ Glenn
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#273088 - 31/12/2005 01:34 Re: Cyclic Redundancy Check? [Re: gbeer]
robricc carpal tunnel Registered: 30/10/2000 Posts: 4931 Loc: New Jersey, USA	Quote: Really! A 2.5 GigaByte file? Dosen't that bust some kind of Windows file size limit? FAT32 can have file sizes up to 4GB. NTFS doesn't have this limit. I think 2.5GB is over some sort of ISO filesystem limit. I think UDF should work though. _________________________ -Rob Riccardelli 80GB 16MB MK2 090000736
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#273089 - 31/12/2005 01:59 Re: Cyclic Redundancy Check? [Re: robricc]
gbeer carpal tunnel Registered: 17/12/2000 Posts: 2665 Loc: Manteca, California	To be honest, I was thinking partly of how the default per process limit is normally 2gb. _________________________ Glenn
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#273090 - 31/12/2005 12:22 Re: Cyclic Redundancy Check? [Re: gbeer]
tman carpal tunnel Registered: 24/12/2001 Posts: 5528	Erm. It doesn't need to load the entire file into memory in one go you know...
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#273091 - 31/12/2005 19:26 Re: Cyclic Redundancy Check? [Re: tman]
gbeer carpal tunnel Registered: 17/12/2000 Posts: 2665 Loc: Manteca, California	yeah, but even I know there's a big gap, in between not having to and not actually doing so. _________________________ Glenn
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#273092 - 01/01/2006 04:30 Re: Cyclic Redundancy Check? [Re: gbeer]
tman carpal tunnel Registered: 24/12/2001 Posts: 5528	It would have to be a very poorly written video player application to require the entire file to be loaded into memory first.
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#273093 - 01/01/2006 13:17 Re: Cyclic Redundancy Check? [Re: tman]
andy carpal tunnel Registered: 10/06/1999 Posts: 5916 Loc: Wivenhoe, Essex, UK	Quote: It would have to be a very poorly written video player application to require the entire file to be loaded into memory first. The sound recorder/wav player app in Windows (before Media Player) used to load the entire wav file into memory before playing it... _________________________ Remind me to change my signature to something more interesting someday
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#273094 - 01/01/2006 13:53 Re: Cyclic Redundancy Check? [Re: andy]
tman carpal tunnel Registered: 24/12/2001 Posts: 5528	Quote: Quote: It would have to be a very poorly written video player application to require the entire file to be loaded into memory first. The sound recorder/wav player app in Windows (before Media Player) used to load the entire wav file into memory before playing it... As I said, poorly written I doubt they envisioned anybody recording anything serious with it so they just went for the easy option. Most video formats are all split up into chunks internally anyway. Especially with the MPEG series of codecs which encode as a variety of frame types so you can go through only reading parts as necessary off the media. If you had to load an entire video file into memory for playback then every DVD player would have to require at least 1GB of RAM to store each VOB. You'd probably need 9GB since reading in 1GB at a time would take awhile and you don't want your film to suddenly stop part the way through to cache the next VOB. I've created 10GB files before by importing video from a miniDV camera. No problems at all when using a NTFS partition and unfortunately I don't have 10GB of RAM so it isn't loading it into memory.
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