Playback on VCD player possible with added files?

[juleeg]

I have a client who is thrilled with his cd-rom made with AMS, but now he wants to know if I can also make it play on VCD players?

I did encode all the mpegs currently in my AMS project as VCD compliant. Seems like a nasty can of worms though...

[Lorne]

Re: Playback on VCD player possible with added files?

In order for a standalone DVD or VCD player to be able to play the video, the disc has to be arranged with a very specific folder structure and a bunch of data files have to be in just the right places.

Technically, however, a VCD or SVCD is pretty much a regular data CD, with one other important exception: VCD and SVCD discs are burned with no error correction data on the discs, so they can hold more information. (That's why you can fit an 805 MB mpg on a 700 MB CDR.)

Normally, the CD recorder will write something like 10 bytes of actual "file" data, and then an extra byte that serves as a sort of error-recovery data. (Those aren't the actual numbers, but you get the idea.) When the CD-ROM drive reads the disc, and encounters bits of data that are unreadable or missing (maybe because of scratches or dust on the disc), it uses that recovery info to "figure out" what the missing piece should be.

That recovery data takes up a bit of room, though. For VCDs and SVCDs, which contain MPEG video, a bunch of errors here and there on the CD probably won't be that noticeable. Who cares if one splotch of black on the screen turns green for a fraction of a second in a 45 minute video? The extra content you can stuff onto a CD is worth more than guarding against playback errors.

Even so, VCDs and SVCDs are essentially still just data files. In fact, they both have a folder designated for extra content, like CD cover images, text files or Word documents full of background info, and anything else that you might want to store with your video data. The stuff wouldn't be viewable on a standalone DVD player, but at least it would still be there for you to access on a PC.

It's possible that putting an AutoPlay application on the root of the CD will allow it to autoplay in a computer's CD-ROM drive, while still playing fine in a standalone DVD player. I haven't tried it, though, and it's possible that it might "break" the VCD/SVCD format somehow, and cause the DVD player to not be able to play the disc.

I say try it on a CDRW and see. Prepare the VCD or SVCD folders and files, and then add the AutoPlay application to the root of the image, and then burn it all together to a CDRW, and see if it works.

[juleeg]

Re: Playback on VCD player possible with added files?

Thanks very much for the rapid response!

I'll give it try and let you know what happens.

[Lorne]

Re: Playback on VCD player possible with added files?

BTW -- if you click on the ISO tab in VCDEasy, it lets you specify files to add to the image. So I'm leaning more toward the "make a VCD with an autoplay menu that only autoruns on PCs is possible" camp.