Using mpeg2 in iMovie

IMovie and iDVD want .dv as their input. The best quality option would be to capture the analog videos as .dv (via a camcorder or a standalone converter box). The edit in iMovie and burn as video-DVD via iDVD. MPEG Streamclip can convert MPEG to .dv but you lose quality in doing so...

On the other hand, IF you don't need to edit the videos, THEN capturing as MPEG might be a good idea: Capture MPEG, then author the MPEGs as video-DVDs via Toast, Sizzle, DVDSP etc. With MPEG Streamclip you can even do some rudimentary editing (straight cuts etc).

See also:

http://www.sjoki.uta.fi/~shmhav/SVCDon_a_Macintosh.html#edit_convertMPEG

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ObSig: I don't benefit from the link.

Demuxing in this case refers to separating the audio signal from the video signal. By doing so, you give yourself the option to do more refined editing of audio with video. The format that is used exclusively by iMovie ( .dv) is a combined format which has some inherent disadvantages for pro level editing. So Matti's suggestion is a good one (ie use a real convertor box). But if you cannot, there is no reason for you to try to fix what is working for you just fine.
By the way, the .mov extension refers to a kind of wrapper that contains video or audio files. The wrapper has tags that make it available for specific applications. For example, you can have an audio piece of media in aiff wrapped in a .mov wrapper which Quicktime can play or edit.

None of the Apple editors use MPEG-2 as input including Final Cut because MPEG-2 is a delivery format and not an editing one, there are not even actual frames each 30th of a second, they are rendered from other (key) frames.

However, while I hate to say it, many Windows programs such as Pinnacle Studio 7 (supposedly the least crashy version as they are on 9 now) and Ulead Video Studio. I used to use both with XP and they are really unstable with other than DV, and not all that great programs with DV either.

All that aside one of my newer acquisitions is a JVC hard drive based MPEG-2 recorder and the DV output from MPEG Streamclip was not all that bad, but I do try to stick to MPEG-2 and trim and cut and make DVD's straight from the MPEG-2 files in Streamclip then Toast if I can. They look very good.

I shoot at the best setting on it as well, 10.5 mb/sec CBR vs. the alternatives that go as low as 1.5. Since at the best setting it stores 7 hours of MPEG-2 capacity is not a huge issue anyway (it stores 37 hours at the lowest setting).

Toast 7 finally has a few themes in it for DVD, nothing like iDVD but better than before which was none.

Since you are stuck using real time capture have you thought of using a DV camera to transcode into DV since there are some decent low priced ones and at least when you are done you have a perfectly good usable DV camera. As opposed to a analog to DV device.

The Apple web sites for iMovie and for FCP can provide some idea of the video cams that can be used with each application. If you can afford it, an investment in a good videocam that captures to minidv tapes will stand you well for a number of years. Most of the brands, Sony, Canon, etc are fire wired enabled and have several models that can serve as "convertors" as well.
In my view starting with an mpeg2 source sort of puts you at a disadvantage since the video is not all that great. When you go to put the material on a DVD for presentation, compression will likely occur again to some extent and you will end up with even more diminished video quality. The DVcam approach will allow to to at least start with the quality of video on the Hi8 or whatever your original source material happens to be. So the only time you will see a loss is after you edit and are putting the edited video onto a DVD for presentation.
Finally a dvcam is a great way to capture video for either iMovie or FCP editing and is the gateway to high value videos for friends,family, and you.

I would think the highest bit rate to allow the best quality for frame rendering would pay off. And it is temporary anyway so what difference does it make anyway right? (Note: 12 mb/sec is still a lot less data than DV is)

DV cameras - connect the analog audio and video cable to the input and then the firewire goes to the Mac. There may be a setting for using it as an A/D converter and you usually leave the tape out. It is always well set out in the manual.

Note to the above - the iM and FC websites are pretty dated as to "approved" cameras. It is pretty hard to find one that won't work, and just buy from a location with a refund/exchange policy.

I have got the same JVC hard drive camcorder and I bought an iMac specifically because of iMovie and iDVD. After 20+ years of PC use and a dozen video programs I wanted something the 2 teenagers could use to get some professional looking results without the headache of Adove Premier. Now that I find out I have to convert my MPEG2 files to DV or Quicktime in order to use the Mac software, why do I need this MAC? Instead it seems like I'm going to degrade my images in order to produce well packaged DVDs. Anybody got a good reason to keep the MAC for movie making with a JVC camera, I can still take it back!

I have to convert my MPEG2 files to DV or Quicktime in order to use the Mac software

MPEG is meant to be a non-editable dead-end and a distribution format of the final product.

But you can edit MPEG if you insist:

Capty MPEG Edit EX ($50) for Mac OS 9/X can do frame-accurate MPEG2 (not VOB or MPEG1) editing with 48 kHz PCM, AC3 or M1A single audio streams. It does this by converting a GOP to uncompressed video at the point of the edit. It supports all legal DVD resolutions. It can join different MPEGs to a single MPEG file and write as DV stream or MOV. It seems to have an iMovie-like interface. I haven't tried it but one review was very positive.

http://www.pixela-1.com/captympeg_editex/

Disclaimer: I don't benefit from this post.

The JVC camcorder did come with the Capty software and I have used it. What I was concerned about was degrading the beautiful image that the camcorder has captured and stored as the MPEG2. It actually stiches stuff together pretty well, but I want to be able to add sound effects, music, and narrative.