digitalFAQ.com Forum - Some questions about old and new iMovie versions

I posted this in an existing thread already, because it fitted there, but since no one answers, I might just open a new thread as sugguested in the Forum note.

Quote:

Originally Posted by premiumcapture: http://www.digitalfaq.com/forum/vide...html#post44654

Avoid DV if you can - it does not reencode well, and this likely the culprit of many Mac issues. It is good and still in use for SD video recording, but due to the 4:1:1 color scheme it tends to turn into crap fairly quickly, especially when dealing with VHS.

Read more: http://www.digitalfaq.com/forum/vide...#ixzz4CXdkiz8z

Did you ever happen to notice, that DV files stored in the iMovie project folder/package are DV and those DVs that you create via "export -> quighest quality" are reported as DVCpro by Mediainfo?

I let someone compare those files and he said:

Quote:

The "capture" (DV) and "pass-through" ('DVCPro') samples are bit identical. What's more, both have 4:2:0 chroma subsampling, which is interesting, as by definition DVCPro(25) is 4:1:1.

So why MediaInfo reports the export file as being "DVCPro" (Commercial Name), I really not sure.

Regardless, I think it's safe to conclude that it is a direct stream copy of the source DV. DV is not a lossless format, and if there was re-encoding going-on, you would expect to pick up some loss in quality on metric analysis. And there is none.

That basic question answered, what might be interesting to determine is whether iMovie truly supports so called "Smart Rendering" of DV, which most Windows-based NLE's do, by default or as an option. By that I mean, if an "effect" is applied to a section of a clip on the timeline, only those frames changed by the effect are re-encoded and the "untouched" frames are passed through (copied). So if only cut edits are applied, there is no re-encoding at all.

Read more: http://www.digitalfaq.com/forum/vide...#ixzz4CXdtG1SK

PS: it also seems to me exporting from iMovie (I am always talking about iMovieHD6 and prior!) as "passthrough" takes longer than with mpegstreamclip.

Any thoughts?

PPS: Oh and I am talking about PAL VHS that had been captured via ADVC-300 over Firewire to (iMovie3), 5 and 6. Not sure, if I discoverd that with vers3, too. Could the strange behaviour, the dvcpro25 4:2:0 be a result of a badly implemented PAL conversion in iMovie? (It being an American app handling European stuff).

Also another observation, if you open iM-3 projects in iM-6 a bit of the begining and the end (seconds) is lost. You first have to open those in iM5 and save them and then they can be opened with no loss in iM-6.[/QUOTE]