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VCD error - cyclic redundancy check error ??



 
 
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  #1  
Old September 11th 03, 05:42 PM
Andy
external usenet poster
 
Posts: n/a
Default VCD error - cyclic redundancy check error ??

Sorry if this is the wrong ng.

I am trying to copy a VCD onto my PC to view it from there (as the VCD won't
work in my DVD player, or my PC from the CDR). So i thought i'd try to copy
it to my hard drive and watch it from there.

However, whilst copying the files over, i get a 'cyclic redundancy check'
error.

a) What is this ?

b) What can i do to correct it and copy the CDR to my Hard drive ?

Cheers
Andy


  #2  
Old September 11th 03, 07:36 PM
Anonymous Joe
external usenet poster
 
Posts: n/a
Default

"Andy" wrote in message
...
Sorry if this is the wrong ng.

I am trying to copy a VCD onto my PC to view it from there (as the VCD

won't
work in my DVD player, or my PC from the CDR). So i thought i'd try to

copy
it to my hard drive and watch it from there.

However, whilst copying the files over, i get a 'cyclic redundancy check'
error.

a) What is this ?

b) What can i do to correct it and copy the CDR to my Hard drive ?

Cheers
Andy


Well, as you've stated yourself, there is a cyclic redudancy check error
(CRC). Now, since these are bad errors, and it won't play in the DVD or the
PC, then I would doubt that copying it will help anyway.

Regardless, you cannot copy it over like you would a normal data file. The
VCD isn't a data disc with MPEG files on it. It is really like an audio CD
substructure with video. As you know, you cannot copy over cd tracks, you
need to use a 3rd party program to "rip" the audio. Same here, you need to
"rip" the video files out of the VCD. I've used VCDGear(GUI) and VCDEasy,
and they both work fine. www.DVDRhelp.com has those for download, however,
I believe VCDEasy is now a $$$ program, but VCDGearGUI is still free.

If it won't work, then it is probably the disc is bad. CRC errors only
occur when there is an error in the main data (which I believe is 2336 bytes
for every sector of 2352 bytes for VCD, normal data is 2048 for the sector
of 2352). Then it will use the rest of the sector for CRC code, which helps
the drive try to fill in the missing bytes based on some mathematical
calculations between the surrounding data and the CRC data. On a normal
data CD there are several layers of protection, C1 and C2, C1 tries to
replace missing data from the 2048 byte user data section, while C2 will try
to fill in the C1 data if there is too much damage to the user or to the C1
itself. On the VCD, as well as audio CD, there is just a C1 protection.
This was felt as enough, since it did two things: only lets data which has
some type of protection already built-in (MPEG has CRC protection in the
files themselves, and a WAV file for the audio CD, the error would be too
small to notice since there are 77 sector for every second, so if only like
10 sectors are bad with unusable data and broken C1, then there is less than
1/7th of a second of bad audio, and two, it allows up to 800MB to be put on
the CD compared with the normal data CD with only 700MB. If it weren't for
this method, the 80min CD would be 70min, and the 74min would be 65 minutes.

If your drive allows C1 error reporting, then you can see if there are a lot
of errors on the disc or not, although I can't tell you what programs do
this. IF you have a modern Liteon, then K's CD Probe will work.....I don't
think Nero lets C1 checking, even though there is an option for it, then
again I never tried it on VCD.


  #3  
Old September 12th 03, 12:54 AM
Robert Hancock
external usenet poster
 
Posts: n/a
Default

You shouldn't need any special software just to copy the DAT file off the
disc, it shows up in the file system like any other. However, special
software may be able to better recover from errors like the one the poster
encountered.

Actually, all CDs have both C1 and C2 error correction. Regular (Mode 1 or
Mode 2 Form 1) data CDs have an additional EDC/ECC layer which allows data
to be recovered in the event an error can't be corrected at the C2 level.
VCDs use Mode 2 Form 2, which has EDC but not ECC, so errors can be detected
but not corrected.

As far as the original problem, trying to copy the file a few more times may
help, as it might be able to get a good read on that sector. Or try reading
it on another drive. Other than that, you'll need some special software.

--
Robert Hancock Saskatoon, SK, Canada
To email, remove "nospam" from
Home Page:
http://www.roberthancock.com/


"Anonymous Joe" wrote in message
news:Tg38b.417715$o%2.189424@sccrnsc02...
"Andy" wrote in message
...
Sorry if this is the wrong ng.

I am trying to copy a VCD onto my PC to view it from there (as the VCD

won't
work in my DVD player, or my PC from the CDR). So i thought i'd try to

copy
it to my hard drive and watch it from there.

However, whilst copying the files over, i get a 'cyclic redundancy

check'
error.

a) What is this ?

b) What can i do to correct it and copy the CDR to my Hard drive ?

Cheers
Andy


Well, as you've stated yourself, there is a cyclic redudancy check error
(CRC). Now, since these are bad errors, and it won't play in the DVD or

the
PC, then I would doubt that copying it will help anyway.

Regardless, you cannot copy it over like you would a normal data file.

The
VCD isn't a data disc with MPEG files on it. It is really like an audio

CD
substructure with video. As you know, you cannot copy over cd tracks, you
need to use a 3rd party program to "rip" the audio. Same here, you need

to
"rip" the video files out of the VCD. I've used VCDGear(GUI) and VCDEasy,
and they both work fine. www.DVDRhelp.com has those for download,

however,
I believe VCDEasy is now a $$$ program, but VCDGearGUI is still free.

If it won't work, then it is probably the disc is bad. CRC errors only
occur when there is an error in the main data (which I believe is 2336

bytes
for every sector of 2352 bytes for VCD, normal data is 2048 for the sector
of 2352). Then it will use the rest of the sector for CRC code, which

helps
the drive try to fill in the missing bytes based on some mathematical
calculations between the surrounding data and the CRC data. On a normal
data CD there are several layers of protection, C1 and C2, C1 tries to
replace missing data from the 2048 byte user data section, while C2 will

try
to fill in the C1 data if there is too much damage to the user or to the

C1
itself. On the VCD, as well as audio CD, there is just a C1 protection.
This was felt as enough, since it did two things: only lets data which has
some type of protection already built-in (MPEG has CRC protection in the
files themselves, and a WAV file for the audio CD, the error would be too
small to notice since there are 77 sector for every second, so if only

like
10 sectors are bad with unusable data and broken C1, then there is less

than
1/7th of a second of bad audio, and two, it allows up to 800MB to be put

on
the CD compared with the normal data CD with only 700MB. If it weren't

for
this method, the 80min CD would be 70min, and the 74min would be 65

minutes.

If your drive allows C1 error reporting, then you can see if there are a

lot
of errors on the disc or not, although I can't tell you what programs do
this. IF you have a modern Liteon, then K's CD Probe will work.....I

don't
think Nero lets C1 checking, even though there is an option for it, then
again I never tried it on VCD.




 




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