Save the the original mpegs or just copy the original vcds I made?...please help! :D

[dyson]

hi
:D
heres my question
I know VCDs or SVCDs dont used checksum to check CD sectors, and so having no data correction....so sometimes dvd readers don't read VCDs or SVCDs properly and I get artifacts.. I know its normal..and happens on old DVD firmwares..
(I use nero and TMPGEncby the way)

now I have the original Mpegs....so what is best?

-Save the Mpegs and every time I make a another vcds use the original mpegs making a new VCD compilation on nero? or
(which would maintain th integrity of the files)

-Just make the VCDS and make copies of it hopping that my cd reader will read properly the original VCDS I made before?
(which might make bad copies of the vcds and tell me they were well recorded)




OR....am I just plain stupid? :S
please correct me if I'm wrong...its been driving me crazy! :S

thanks y'all :D

[jsoto]

Hi dyson,

(S)VCDs have CRC error detection capabilities, but not error correction capabilities. That means, the reader usually detects the errors and, if, it is on a PC usually tells you there is a corrupt file and there is no way to recover it. In a settop, the error is skipped and some atrifacts will appear.

But, in my experience, there are other reasons for artifacts, related with the recording speed (try with 4x or 8x, but not more) and also, with the CD brand.

I have an old settop (Thomson, BTW) which only works completely fine with Verbatim, may be other brand works too, but I've tried 3 or 4 and always it was showing ocasionally some artifacts, hangs one second, or things tike that. The same CDs work fine in other settops, so they are not corrupt.

About your question, well, really it is up to you

I do not know a tool able to "recover" a corrupt mpg, and it is clear that the probability of loosing a (S)VCD file is higher than the same file in a normal data CD disc, but obviously, the maximum file size which fits in a (S)VCD (800 MB in 80 minCD) will not fit in a normal data CD (700 MB in the same 80 min CD).

Hope it helps.

[dyson]

yeap I had thought of that too....so I think Ill just save the mpegs.... :(...they art too important.

so I'll make s(vcds) up to 700 megs only thanks :D

[jsoto]

Hi again

To have the complete information...

Some time ago, I had found this info in the Internet, may be in this forum (and saved it on my HD), but I do not remember where (sorry, I can not give you the link):

------------------------------------------------------------------
A normal data CD saves 2048 bytes of data per sector, the rest is used for the error correction. A video CD has no error correction, so a larger number of sectors will fit on the CD:
DataCD: CD-R with 330.000 sectors * 2048 bytes/sector = 675.840.000 bytes = 644.5 MB
VideoCD: CD-R with 330.000 sectors * 2352 bytes/sector = 776.160.000 bytes = 740.2 MB
DataCD: CD-R with 360.000 sectors * 2048 bytes/sector = 737.280.000 bytes = 703.1 MB
VideoCD: CD-R with 360.000 sectors * 2352 bytes/sector = 846.720.000 bytes = 807.5 MB
Of course all CD-R's have a few MB more to spend plus you can overburn them. Use the CDRIdentifier to find out how much your CD-R can hold. As you have seen, the limits to stay below are 740 MB for a 650MB CD-R and 807 MB for a 700MB CD-R.

If you overburn your CD's then select disk at once.
------------------------------------------------------

Cheers.

[jsoto]

Well, I have to correct myself:

According http://www.disctronics.co.uk/technology/cd-rom/cdrom_spec.htm
One sector has 2352 bytes (independent of the mode)
Mode 1 (normal data disc):
SYNC: 12
HEADER: 4
USER DATA: 2048
Error Detection: 4
Unused: 8
Error Correction:276

Mode 2 form 2 (i.e.: VCD and SVCD):
SYNC: 12
HEADER: 4
SUBHEADER: 8
USER DATA: 2324
Error Detection: 4

So, assuming 74 min=333.000 sectors and 80 min=360.000 sectors (I am unsure about the accuracy of these data, because some sectors are needed for the file system and for start of track 1 in CD XA)

DataCD: CD-R with 333.000 sectors * 2048 bytes/sector = 681.984.000 bytes = 650,39 MB
VideoCD: CD-R with 333.000 sectors * 2324 bytes/sector = 766.920.000 bytes = 738.04 MB
DataCD: CD-R with 360.000 sectors * 2048 bytes/sector = 737.280.000 bytes = 703.1 MB
VideoCD: CD-R with 360.000 sectors * 2324 bytes/sector = 836.640.000 bytes = 797,88 MB

Cheers