which vdo codecs

[stef24]

A friend makes backups of some dvd's i buy for me, so that i can watch them in my room on my pc (i dont have a dvd drive). however i have problems watching some of them. my software says the file is corrupt or unsupported format

he says that i should just have the divx and xvid codecs installed and it should work, since he encodes them with either of those two systems. is he telling the truth? is it possible i have the wrong version of the codecs? or the wrong audio decoders?

thx alot

[Cyberman]

Download GSpot and see what it tells you.

It *could* be that you have the wrong version, if it´s VERY old - like DivX 5.0.1 or so. There have been some serious changes in newer versions.

[stef24]

k sorry for the late reply, my wifi has been acting up.

i ran gspot on the file and it says "not a valid AVI file". pretty clear answer

what could cause this? or yet better, fix it?

[rigel]

Are those video files on CD?
If so, then have you verified that your friend can play them?
There could be a problem with those CD-s.

[stef24]

i have them on my hard drive now.

just as background, to a certain extent i know what im doing. ive converted several formats, managed to back up my dvd's to different formats so im familiar with the basics.

but this really puzzles me. could it be my friend got these off p2p applications and they were just bad from the start?

in that case id like to know if these are faulty files planted there on purpose, or something went wrong along the way, with the downloading?

what destroys a file?

[rigel]

Are you familiar with VirtualDub?
try to open them in VirtualDub's hex editor (Tools->HexEditor, and then File->Open).
Now on the righthand column you should see several words, among them "RIFF", "AVI", "LIST", "vids", etc. You should see them without the need of scrolling forward. If you see none of these, then it is certainly not an avi file! If you see only some of them, then something is very wrong indeed.

[Cyberman]

(Why did no one ask this till yet?)

What extensions do these files have? Are they actually "AVI" or something else?
Though that´s by no means a sure indication, it might give a hint.
To be valid video, it should be at least one of these:

AVI
MKV
MP4
WMV
ASF
OGM

MPG

To contain DivX/XviD, it mustn´t be MPG(unless the extension is changed, it´s a mere information nowadays, neither forced nor checked by most programs)

[stef24]

ok intresting. i have one with an mpeg extension of which gspot says "not a valid avi file" ... some kind of conflict here? gspot is unable to render this file and says its of an unknown filetype

renamed the file with ".avi" at the end, no difference

[rigel]

By the way - gspot says "Not a valid avi file" for any file it doesn't recognize as something else.
So it doesn't mean that this particular file is actually an avi file.
IMHO the best solution would be if you could upload the beginning of the file (not much needed, 100 KB or so is enough) somewhere.

[stef24]

how do i upload only a part of a file?

[rigel]

You need a tool to extract the beginning of a file.
There are several tools available for this kind of a task, but I would just recommend to use VirtualDub (which you maybe already have if you have some experience in converting/ripping, but if you haven't then it is available from the download section right here at doom9)
From VirtualDub's "Tools" menu select "Hex Editor", then from the hex editor's "File" menu select "Open".
Then from the "Edit" menu select "Extract segment"
Leave the "address" to 0, and type 20000 to "Lenght"
Press "OK" and save the file with a name of your choice.
now you have 128 KB piece of the file.

[Cyberman]

Originally posted by stef24
ok intresting. i have one with an mpeg extension of which gspot says "not a valid avi file"
Then it´s not an AVI file. The extension probably is right - it´s an MPeg file, I guess.

renamed the file with ".avi" at the end, no difference
It shouldn´t make any difference - GSPot analyzes the file itself, not the name.
Leave it as it is, unless you know it´s wrong.